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Bercioux D, Klapwijk TM, Bergeret FS. Transport Properties of an Electron-Hole Bilayer in Contact with a Superconductor Hybrid Junction. Phys Rev Lett 2017; 119:067001. [PMID: 28949615 DOI: 10.1103/physrevlett.119.067001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Indexed: 06/07/2023]
Abstract
We investigate the transport properties of a junction consisting of an electron-hole bilayer in contact with normal and superconducting leads. The electron-hole bilayer is considered as a semimetal with two electronic bands. We assume that in the region between the contacts the system hosts an exciton condensate described by a BCS-like model with a gap Γ in the quasiparticle density of states. We first discuss how the subgap electronic transport through the junction is mainly governed by the interplay between two kinds of reflection processes at the interfaces: the standard Andreev reflection at the interface between the superconductor and the exciton condensate, and a coherent crossed reflection at the semimetal-exciton-condensate interface that converts electrons from one layer into the other. We show that the differential conductance of the junction shows a minimum at voltages of the order of Γ/e. Such a minimum can be seen as a direct hallmark of the existence of the gapped excitonic state.
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Affiliation(s)
- D Bercioux
- Donostia International Physics Center (DIPC), Manuel de Lardizbal 4, E-20018 San Sebastián, Spain
- IKERBASQUE, Basque Foundation of Science, 48011 Bilbao, Basque Country, Spain
| | - T M Klapwijk
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - F S Bergeret
- Donostia International Physics Center (DIPC), Manuel de Lardizbal 4, E-20018 San Sebastián, Spain
- Centro de Física de Materiales (CFM-MPC) Centro Mixto CSIC-UPV/EHU, 20018 Donostia-San Sebastian, Basque Country, Spain
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2
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Semenov AV, Devyatov IA, de Visser PJ, Klapwijk TM. Coherent Excited States in Superconductors due to a Microwave Field. Phys Rev Lett 2016; 117:047002. [PMID: 27494495 DOI: 10.1103/physrevlett.117.047002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Indexed: 06/06/2023]
Abstract
We describe theoretically the depairing effect of a microwave field on diffusive s-wave superconductors. The ground state of the superconductor is altered qualitatively in analogy to the depairing due to a dc current. In contrast to dc depairing, the density of states acquires, for microwaves with frequency ω_{0}, steps at multiples of the photon energy Δ±nℏω_{0} and shows an exponential-like tail in the subgap regime. We show that this ac depairing explains the measured frequency shift of a superconducting resonator with microwave power at low temperatures.
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Affiliation(s)
- A V Semenov
- Moscow State Pedagogical University, 1 Malaya Pirogovskaya Street, Moscow 119992, Russia
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow 141700, Russia
| | - I A Devyatov
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow 141700, Russia
- Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, 1(2), Leninskie gory, GSP-1, Moscow 119991, Russia
| | - P J de Visser
- Kavli Institute of NanoScience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
- SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
| | - T M Klapwijk
- Moscow State Pedagogical University, 1 Malaya Pirogovskaya Street, Moscow 119992, Russia
- Kavli Institute of NanoScience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
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3
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Endo A, Yates SJC, Bueno J, Thoen DJ, Murugesan V, Baryshev AM, Klapwijk TM, van der Werf PP, Baselmans JJA. Superconducting Coplanar Waveguide Filters for Submillimeter Wave On-Chip Filterbank Spectrometers. J Low Temp Phys 2016; 184:412-417. [PMID: 27340291 PMCID: PMC4880640 DOI: 10.1007/s10909-016-1579-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 03/02/2016] [Indexed: 06/06/2023]
Abstract
We show the first experimental results which prove that superconducting NbTiN coplanar-waveguide resonators can achieve a loaded Q factor in excess of 800 in the 350 GHz band. These resonators can be used as narrow band pass filters for on-chip filter bank spectrometers for astronomy. Moreover, the low-loss coplanar waveguide technology provides an interesting alternative to microstrip lines for constructing large scale submillimeter wave electronics in general.
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Affiliation(s)
- A. Endo
- />Department of Microelectronics, Faculty of Electrical Engineering, Mathematics and Computer Science, Delft University of Technology, Mekelweg 4, 2628 CD Delft, The Netherlands
- />Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - S. J. C. Yates
- />SRON Netherlands Institute for Space Research, Landleven 12, 9747 AD Groningen, The Netherlands
| | - J. Bueno
- />SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
| | - D. J. Thoen
- />Department of Microelectronics, Faculty of Electrical Engineering, Mathematics and Computer Science, Delft University of Technology, Mekelweg 4, 2628 CD Delft, The Netherlands
| | - V. Murugesan
- />SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
| | - A. M. Baryshev
- />SRON Netherlands Institute for Space Research, Landleven 12, 9747 AD Groningen, The Netherlands
- />Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen, The Netherlands
| | - T. M. Klapwijk
- />Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
- />Physics Department, Moscow State Pedagogical University, 119991 Moscow, Russia
| | - P. P. van der Werf
- />Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
| | - J. J. A. Baselmans
- />Department of Microelectronics, Faculty of Electrical Engineering, Mathematics and Computer Science, Delft University of Technology, Mekelweg 4, 2628 CD Delft, The Netherlands
- />SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
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4
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Yang Y, Fedorov G, Shafranjuk SE, Klapwijk TM, Cooper BK, Lewis RM, Lobb CJ, Barbara P. Electronic Transport and Possible Superconductivity at Van Hove Singularities in Carbon Nanotubes. Nano Lett 2015; 15:7859-7866. [PMID: 26506109 DOI: 10.1021/acs.nanolett.5b02564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Van Hove singularities (VHSs) are a hallmark of reduced dimensionality, leading to a divergent density of states in one and two dimensions and predictions of new electronic properties when the Fermi energy is close to these divergences. In carbon nanotubes, VHSs mark the onset of new subbands. They are elusive in standard electronic transport characterization measurements because they do not typically appear as notable features and therefore their effect on the nanotube conductance is largely unexplored. Here we report conductance measurements of carbon nanotubes where VHSs are clearly revealed by interference patterns of the electronic wave functions, showing both a sharp increase of quantum capacitance, and a sharp reduction of energy level spacing, consistent with an upsurge of density of states. At VHSs, we also measure an anomalous increase of conductance below a temperature of about 30 K. We argue that this transport feature is consistent with the formation of Cooper pairs in the nanotube.
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Affiliation(s)
- Y Yang
- Department of Physics, Georgetown University , Washington, District of Columbia 20057, United States
| | - G Fedorov
- Department of Physics, Georgetown University , Washington, District of Columbia 20057, United States
| | - S E Shafranjuk
- Department of Physics and Astronomy, Northwestern University , Evanston, Illinois 60208, United States
| | - T M Klapwijk
- Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands
- Laboratory for Quantum Limited Devices, Physics Department, Moscow State Pedagogical University , 29 Malaya Pirogovskaya Street, Moscow, 119992, Russia
| | - B K Cooper
- Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands
| | - R M Lewis
- Department of Physics, CNAM, and JQI , University of Maryland , College Park, Maryland 20742, United States
| | - C J Lobb
- Department of Physics, CNAM, and JQI , University of Maryland , College Park, Maryland 20742, United States
| | - P Barbara
- Department of Physics, Georgetown University , Washington, District of Columbia 20057, United States
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5
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de Visser PJ, Baselmans JJA, Bueno J, Llombart N, Klapwijk TM. Fluctuations in the electron system of a superconductor exposed to a photon flux. Nat Commun 2014; 5:3130. [PMID: 24496036 PMCID: PMC3925999 DOI: 10.1038/ncomms4130] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 12/17/2013] [Indexed: 11/09/2022] Open
Abstract
In a superconductor, in which electrons are paired, the density of unpaired electrons should become zero when approaching zero temperature. Therefore, radiation detectors based on breaking of pairs promise supreme sensitivity, which we demonstrate using an aluminium superconducting microwave resonator. Here we show that the resonator also enables the study of the response of the electron system of the superconductor to pair-breaking photons, microwave photons and varying temperatures. A large range in radiation power (at 1.54 THz) can be chosen by carefully filtering the radiation from a blackbody source. We identify two regimes. At high radiation power, fluctuations in the electron system caused by the random arrival rate of the photons are resolved, giving a straightforward measure of the optical efficiency (48±8%) and showing an unprecedented detector sensitivity. At low radiation power, fluctuations are dominated by excess quasiparticles, the number of which is measured through their recombination lifetime. Electromagnetic radiation detectors based on superconducting resonators have a range of potential uses from astronomy to quantum computing. De Visser et al. demonstrate a superconductor detector with unprecedented sensitivity limited only by fluctuations in the electron system of the superconductor.
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Affiliation(s)
- P J de Visser
- 1] SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA, Utrecht, The Netherlands [2] Kavli Institute of NanoScience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands
| | - J J A Baselmans
- SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA, Utrecht, The Netherlands
| | - J Bueno
- SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA, Utrecht, The Netherlands
| | - N Llombart
- Terahertz Sensing Group, Faculty of Electrical Engineering, Mathematics and Computer Science, Delft University of Technology, Mekelweg 4, 2628 CD, Delft, The Netherlands
| | - T M Klapwijk
- Kavli Institute of NanoScience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands
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6
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de Visser PJ, Goldie DJ, Diener P, Withington S, Baselmans JJA, Klapwijk TM. Evidence of a nonequilibrium distribution of quasiparticles in the microwave response of a superconducting aluminum resonator. Phys Rev Lett 2014; 112:047004. [PMID: 24580483 DOI: 10.1103/physrevlett.112.047004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Indexed: 06/03/2023]
Abstract
In a superconductor, absorption of photons with an energy below the superconducting gap leads to redistribution of quasiparticles over energy and thus induces a strong nonequilibrium quasiparticle energy distribution. We have measured the electrodynamic response, quality factor, and resonant frequency of a superconducting aluminium microwave resonator as a function of microwave power and temperature. Below 200 mK, both the quality factor and resonant frequency decrease with increasing microwave power, consistent with the creation of excess quasiparticles due to microwave absorption. Counterintuitively, above 200 mK, the quality factor and resonant frequency increase with increasing power. We demonstrate that the effect can only be understood by a nonthermal quasiparticle distribution.
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Affiliation(s)
- P J de Visser
- SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands and Kavli Institute of NanoScience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - D J Goldie
- Cavendish Laboratory, Cambridge University, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - P Diener
- SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
| | - S Withington
- Cavendish Laboratory, Cambridge University, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - J J A Baselmans
- SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
| | - T M Klapwijk
- Kavli Institute of NanoScience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
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7
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Ranjan V, de Lange G, Schutjens R, Debelhoir T, Groen JP, Szombati D, Thoen DJ, Klapwijk TM, Hanson R, DiCarlo L. Probing dynamics of an electron-spin ensemble via a superconducting resonator. Phys Rev Lett 2013; 110:067004. [PMID: 23432295 DOI: 10.1103/physrevlett.110.067004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Indexed: 06/01/2023]
Abstract
We study spin relaxation and diffusion in an electron-spin ensemble of nitrogen impurities in diamond at low temperature (0.25-1.2 K) and polarizing magnetic field (80-300 mT). Measurements exploit field-controlled coupling of the ensemble to two modes of a transmission-line resonator. The observed temperature-independent spin relaxation time indicates that spin outdiffusion across the mode volume dominates over spin-lattice relaxation. Depolarization of one hyperfine-split subensemble by pumping of another indicates fast cross relaxation, with implications for the use of subensembles as independent quantum memories.
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Affiliation(s)
- V Ranjan
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
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8
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Driessen EFC, Coumou PCJJ, Tromp RR, de Visser PJ, Klapwijk TM. Strongly disordered TiN and NbTiN s-wave superconductors probed by microwave electrodynamics. Phys Rev Lett 2012; 109:107003. [PMID: 23005319 DOI: 10.1103/physrevlett.109.107003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Indexed: 06/01/2023]
Abstract
We probe the effects of strong disorder (2.4<k(F)l<8.6) on superconductivity in thin films of niobium titanium nitride and titanium nitride by measuring the microwave electrodynamics in coplanar waveguide resonators. We find a gradual evolution of the electromagnetic response with disorder, deviating from BCS theory, for both materials. This result can be understood as due to changes in the quasiparticle density of states, induced by the short elastic scattering length. The observations are consistent with a model using an effective pair breaker, dependent on the level of disorder.
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Affiliation(s)
- E F C Driessen
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
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9
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de Visser PJ, Baselmans JJA, Diener P, Yates SJC, Endo A, Klapwijk TM. Number fluctuations of sparse quasiparticles in a superconductor. Phys Rev Lett 2011; 106:167004. [PMID: 21599404 DOI: 10.1103/physrevlett.106.167004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 03/25/2011] [Indexed: 05/30/2023]
Abstract
We have directly measured quasiparticle number fluctuations in a thin film superconducting Al resonator in thermal equilibrium. The spectrum of these fluctuations provides a measure of both the density and the lifetime of the quasiparticles. We observe that the quasiparticle density decreases exponentially with decreasing temperature, as theoretically predicted, but saturates below 160 mK to 25-55/μm(3). We show that this saturation is consistent with the measured saturation in the quasiparticle lifetime, which also explains similar observations in qubit decoherence times.
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Affiliation(s)
- P J de Visser
- SRON National Institute for Space Research, Utrecht, The Netherlands.
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10
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Khosropanah P, Baryshev A, Zhang W, Jellema W, Hovenier JN, Gao JR, Klapwijk TM, Paveliev DG, Williams BS, Kumar S, Hu Q, Reno JL, Klein B, Hesler JL. Phase locking of a 2.7 THz quantum cascade laser to a microwave reference. Opt Lett 2009; 34:2958-2960. [PMID: 19794781 DOI: 10.1364/ol.34.002958] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We demonstrate the phase locking of a 2.7 THz metal-metal waveguide quantum cascade laser (QCL) to an external microwave signal. The reference is the 15th harmonic, generated by a semiconductor superlattice nonlinear device, of a signal at 182 GHz, which itself is generated by a multiplier chain (x12) from a microwave synthesizer at approximately 15 GHz. Both laser and reference radiations are coupled into a bolometer mixer, resulting in a beat signal, which is fed into a phase-lock loop. The spectral analysis of the beat signal confirms that the QCL is phase locked. This result opens the possibility to extend heterodyne interferometers into the far-infrared range.
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Affiliation(s)
- P Khosropanah
- SRON Netherlands Institute for Space Research, Landleven 12, 9747 AD Groningen, The Netherlands
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11
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Barends R, Baselmans JJA, Yates SJC, Gao JR, Hovenier JN, Klapwijk TM. Quasiparticle relaxation in optically excited high-Q superconducting resonators. Phys Rev Lett 2008; 100:257002. [PMID: 18643694 DOI: 10.1103/physrevlett.100.257002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Indexed: 05/26/2023]
Abstract
The quasiparticle relaxation time in superconducting films has been measured as a function of temperature using the response of the complex conductivity to photon flux. For tantalum and aluminum, chosen for their difference in electron-phonon coupling strength, we find that at high temperatures the relaxation time increases with decreasing temperature, as expected for electron-phonon interaction. At low temperatures we find in both superconducting materials a saturation of the relaxation time, suggesting the presence of a second relaxation channel not due to electron-phonon interaction.
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Affiliation(s)
- R Barends
- Kavli Institute of NanoScience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
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12
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Hajenius M, Khosropanah P, Hovenier JN, Gao JR, Klapwijk TM, Barbieri S, Dhillon S, Filloux P, Sirtori C, Ritchie DA, Beere HE. Surface plasmon quantum cascade lasers as terahertz local oscillators. Opt Lett 2008; 33:312-314. [PMID: 18278094 DOI: 10.1364/ol.33.000312] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We characterize a heterodyne receiver based on a surface-plasmon waveguide quantum cascade laser (QCL) emitting at 2.84 THz as a local oscillator, and an NbN hot electron bolometer as a mixer. We find that the envelope of the far-field pattern of the QCL is diffraction-limited and superimposed onto interference fringes, which are similar to those found in narrow double-metal waveguide QCLs. Compared to the latter, a more directional beam allows for better coupling of the radiation power to the mixer. We obtain a receiver noise temperature of 1050 K when the mixer is at 2 K, which, to our knowledge, is the highest sensitivity reported at frequencies beyond 2.5 THz.
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Affiliation(s)
- M Hajenius
- Kavli Institute of NanoScience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands
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13
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Abstract
We analyze theoretically adiabatic quantum pumping through a normal conductor that couples the normal regions of two superconductor - normal-metal - superconductor Josephson junctions. By using the phases of the superconducting order parameter in the superconducting contacts as pumping parameters, we demonstrate that a nonzero pumped charge can flow through the device. The device exploits the evolution of the superconducting phases due to the ac Josephson effect, and can therefore be operated at very high frequency, resulting in a pumped current as large as a few nanoamperes. The experimental relevance of our calculations is discussed.
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Affiliation(s)
- S Russo
- Kavli Institute of Nanoscience, Faculty of Applied Science, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands
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14
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Orlova EE, Hovenier JN, Klaassen TO, Kasalynas I, Adam AJL, Gao JR, Klapwijk TM, Williams BS, Kumar S, Hu Q, Reno JL. Antenna model for wire lasers. Phys Rev Lett 2006; 96:173904. [PMID: 16712299 DOI: 10.1103/physrevlett.96.173904] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Indexed: 05/09/2023]
Abstract
An antenna model is proposed for long (L >> A) lasers with subwavelength cross sections (wire lasers). It is shown that the far-field pattern of the wire lasers is determined by the ratio of the wavelength to the length. The radiation of the wire laser is predicted to be concentrated in a narrow beam theta approximately radical(2lambda/L) for laser modes where the longitudinal phase velocity is in synchronism with the velocity of light in air. Experimental results obtained using a terahertz quantum cascade wire laser are in agreement with the model.
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Affiliation(s)
- E E Orlova
- Institute for Physics of Microstructures, Russian Academy of Sciences, Nishny Novgorod GSP-105.
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15
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Abstract
We study the influence of a voltage-driven nonequilibrium of quasiparticles on the properties of short mesoscopic superconducting wires. We employ a numerical calculation based upon the Usadel equation. Going beyond linear response, we find a nonthermal energy distribution of the quasiparticles caused by the applied bias voltage. It is demonstrated that this nonequilibrium drives the system from the superconducting state to the normal state, at a current density far below the critical depairing current density.
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Affiliation(s)
- R S Keizer
- Kavli Institute of NanoScience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
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16
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Anissimova S, Venkatesan A, Shashkin AA, Sakr MR, Kravchenko SV, Klapwijk TM. Magnetization of a strongly interacting two-dimensional electron system in perpendicular magnetic fields. Phys Rev Lett 2006; 96:046409. [PMID: 16486862 DOI: 10.1103/physrevlett.96.046409] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2005] [Indexed: 05/06/2023]
Abstract
We measure the thermodynamic magnetization of a low-disordered, strongly correlated two-dimensional electron system in silicon in perpendicular magnetic fields. A new, parameter-free method is used to directly determine the spectrum characteristics (Landé g factor and the cyclotron mass) when the Fermi level lies outside the spectral gaps and the interlevel interactions between quasiparticles are avoided. Intralevel interactions are found to strongly modify the magnetization, without affecting the determined g* and m*.
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Affiliation(s)
- S Anissimova
- Physics Department, Northeastern University, Boston, Massachusetts 02115, USA
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17
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Keizer RS, Goennenwein STB, Klapwijk TM, Miao G, Xiao G, Gupta A. A spin triplet supercurrent through the half-metallic ferromagnet CrO2. Nature 2006; 439:825-7. [PMID: 16482152 DOI: 10.1038/nature04499] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Accepted: 11/29/2005] [Indexed: 11/09/2022]
Abstract
In general, conventional superconductivity should not occur in a ferromagnet, though it has been seen in iron under pressure. Moreover, theory predicts that the current is always carried by pairs of electrons in a spin singlet state, so conventional superconductivity decays very rapidly when in contact with a ferromagnet, which normally prohibits the existence of singlet pairs. It has been predicted that this rapid spatial decay would not occur if spin triplet superconductivity could be induced in the ferromagnet. Here we report a Josephson supercurrent through the strong ferromagnet CrO2, from which we infer that it is a spin triplet supercurrent. Our experimental set-up is different from those envisaged in the earlier predictions, but we conclude that the underlying physical explanation for our result is a conversion from spin singlet pairs to spin triplets at the interface. The supercurrent can be switched with the direction of the magnetization, analogous to spin valve transistors, and therefore could enable magnetization-controlled Josephson junctions.
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Affiliation(s)
- R S Keizer
- Kavli Institute of NanoScience, Faculty of Applied Sciences, Delft University of Technology, 2628 CJ, Delft, The Netherlands.
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18
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Shashkin AA, Anissimova S, Sakr MR, Kravchenko SV, Dolgopolov VT, Klapwijk TM. Pauli spin susceptibility of a strongly correlated two-dimensional electron liquid. Phys Rev Lett 2006; 96:036403. [PMID: 16486743 DOI: 10.1103/physrevlett.96.036403] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2005] [Indexed: 05/06/2023]
Abstract
Thermodynamic measurements reveal that the Pauli spin susceptibility of strongly correlated two-dimensional electrons in silicon grows critically at low electron densities--behavior that is characteristic of the existence of a phase transition.
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Affiliation(s)
- A A Shashkin
- Physics Department, Northeastern University, Boston, Massachusetts 02115, USA
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Russo S, Kroug M, Klapwijk TM, Morpurgo AF. Experimental observation of bias-dependent nonlocal Andreev reflection. Phys Rev Lett 2005; 95:027002. [PMID: 16090710 DOI: 10.1103/physrevlett.95.027002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2005] [Indexed: 05/03/2023]
Abstract
We investigate transport through hybrid structures consisting of two normal metal leads connected via tunnel barriers to one common superconducting electrode. We find clear evidence for the occurrence of nonlocal Andreev reflection and elastic cotunneling through a superconductor when the separation of the tunnel barrier is comparable to the superconducting coherence length. The probability of the two processes is energy dependent, with elastic cotunneling dominating at low energy and nonlocal Andreev reflection at higher energies. The energy scale of the crossover is found to be the Thouless energy of the superconductor, which indicates the phase coherence of the processes. Our results are relevant for the realization of recently proposed entangler devices.
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Affiliation(s)
- S Russo
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
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20
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Meijer FE, Morpurgo AF, Klapwijk TM, Nitta J. Universal spin-induced time reversal symmetry breaking in two-dimensional electron gases with Rashba spin-orbit interaction. Phys Rev Lett 2005; 94:186805. [PMID: 15904395 DOI: 10.1103/physrevlett.94.186805] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2004] [Indexed: 05/02/2023]
Abstract
We have experimentally studied the spin-induced time reversal symmetry (TRS) breaking as a function of the relative strength of the Zeeman energy (E(Z)) and the Rashba spin-orbit interaction energy (E(SOI)), in InGaAs-based 2D electron gases. We find that the TRS breaking, and hence the associated dephasing time tau(phi)(B), saturates when E(Z) becomes comparable to E(SOI). Moreover, we show that the spin-induced TRS breaking mechanism is a universal function of the ratio E(Z)/E(SOI), within the experimental accuracy.
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Affiliation(s)
- F E Meijer
- Kavli Institute of NanoScience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
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Jaroszyński J, Popović D, Klapwijk TM. Magnetic-field dependence of the anomalous noise behavior in a two-dimensional electron system in silicon. Phys Rev Lett 2004; 92:226403. [PMID: 15245243 DOI: 10.1103/physrevlett.92.226403] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2003] [Indexed: 05/24/2023]
Abstract
Studies of low-frequency resistance noise show that the dramatic change in the dynamics of the two-dimensional electron system (2DES) in Si that occurs near the metal-insulator transition (MIT) persists in high parallel magnetic fields B such that the 2DES is fully spin polarized. This strongly suggests that charge, as opposed to spin, degrees of freedom are responsible for this effect. In the metallic phase, however, noise is suppressed by a parallel B, pointing to the role of spins. At low B, the temperature dependence of conductivity in the metallic phase provides evidence for a MIT.
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Affiliation(s)
- J Jaroszyński
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
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23
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Meijer EJ, de Leeuw DM, Setayesh S, van Veenendaal E, Huisman BH, Blom PWM, Hummelen JC, Scherf U, Kadam J, Klapwijk TM. Solution-processed ambipolar organic field-effect transistors and inverters. Nat Mater 2003; 2:678-682. [PMID: 14502272 DOI: 10.1038/nmat978] [Citation(s) in RCA: 328] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2003] [Accepted: 08/14/2003] [Indexed: 05/24/2023]
Abstract
There is ample evidence that organic field-effect transistors have reached a stage where they can be industrialized, analogous to standard metal oxide semiconductor (MOS) transistors. Monocrystalline silicon technology is largely based on complementary MOS (CMOS) structures that use both n-type and p-type transistor channels. This complementary technology has enabled the construction of digital circuits, which operate with a high robustness, low power dissipation and a good noise margin. For the design of efficient organic integrated circuits, there is an urgent need for complementary technology, where both n-type and p-type transistor operation is realized in a single layer, while maintaining the attractiveness of easy solution processing. We demonstrate, by using solution-processed field-effect transistors, that hole transport and electron transport are both generic properties of organic semiconductors. This ambipolar transport is observed in polymers based on interpenetrating networks as well as in narrow bandgap organic semiconductors. We combine the organic ambipolar transistors into functional CMOS-like inverters.
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Affiliation(s)
- E J Meijer
- Philips Research Laboratories, Professor Holstlaan 4, 5656 AA Eindhoven, The Netherlands
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24
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Rahimi M, Anissimova S, Sakr MR, Kravchenko SV, Klapwijk TM. Coherent backscattering near the two-dimensional metal-insulator transition. Phys Rev Lett 2003; 91:116402. [PMID: 14525446 DOI: 10.1103/physrevlett.91.116402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2003] [Indexed: 05/24/2023]
Abstract
We have studied corrections to conductivity due to the coherent backscattering in low-disordered two-dimensional electron systems in silicon for a range of electron densities including the vicinity of the metal-insulator transition, where the dramatic increase of the spin susceptibility has been observed earlier. We show that the corrections, which exist deeper in the metallic phase, weaken upon approaching the transition and practically vanish at the critical density, thus suggesting that the localization is suppressed near and at the transition even in zero field.
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Affiliation(s)
- Maryam Rahimi
- Physics Department, Northeastern University, Boston, Massachusetts 02115, USA
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25
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Shashkin AA, Rahimi M, Anissimova S, Kravchenko SV, Dolgopolov VT, Klapwijk TM. Spin-independent origin of the strongly enhanced effective mass in a dilute 2D electron system. Phys Rev Lett 2003; 91:046403. [PMID: 12906681 DOI: 10.1103/physrevlett.91.046403] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2003] [Indexed: 05/24/2023]
Abstract
We accurately measure the effective mass in a dilute two-dimensional electron system in silicon by analyzing the temperature dependence of the Shubnikov-de Haas oscillations in the low-temperature limit. A sharp increase of the effective mass with decreasing electron density is observed. We find that the enhanced effective mass is independent of the degree of spin polarization, which points to a spin-independent origin of the mass enhancement and is in contradiction with existing theories.
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Affiliation(s)
- A A Shashkin
- Physics Department, Northeastern University, Boston, Massachusetts 02115, USA
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26
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Jaroszyński J, Popović D, Klapwijk TM. Universal behavior of the resistance noise across the metal-insulator transition in silicon inversion layers. Phys Rev Lett 2002; 89:276401. [PMID: 12513226 DOI: 10.1103/physrevlett.89.276401] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2002] [Indexed: 05/24/2023]
Abstract
Studies of low-frequency resistance noise show that the glassy freezing of the two-dimensional (2D) electron system in the vicinity of the metal-insulator transition occurs in all Si inversion layers. The size of the metallic glass phase, which separates the 2D metal and the (glassy) insulator, depends strongly on disorder, becoming extremely small in high-mobility samples. The behavior of the second spectrum, an important fourth-order noise statistic, indicates the presence of long-range correlations between fluctuators in the glassy phase, consistent with the hierarchical picture of glassy dynamics.
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Affiliation(s)
- J Jaroszyński
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA
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27
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Baselmans JJA, Heikkilä TT, van Wees BJ, Klapwijk TM. Direct observation of the transition from the conventional superconducting state to the pi state in a controllable Josephson junction. Phys Rev Lett 2002; 89:207002. [PMID: 12443501 DOI: 10.1103/physrevlett.89.207002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2002] [Indexed: 05/24/2023]
Abstract
We measure the full supercurrent-phase relation of a controllable pi junction around the transition from the conventional 0 state to the pi state. We show that around the transition the Josephson supercurrent-phase relation changes from I(sc) approximately I(c)sin((phi) to I(sc) approximately I(c)sin((2phi). This implies that, around the transition, two minima in the junction free energy exist, one at phi=0 and one at phi=pi, whereas only one minimum exists at the 0 state (at phi=0) and at the pi state (at phi=pi). Theoretical calculations based on the quasiclassical theory are in good agreement with the observed behavior.
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Affiliation(s)
- J J A Baselmans
- Department of Applied Physics and Materials Science Center, University of Groningen, Nijenborg 4, 9747 AG Groningen, The Netherlands
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28
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Shashkin AA, Kravchenko SV, Klapwijk TM. Metal-insulator transition in a 2D electron gas: equivalence of two approaches for determining the critical point. Phys Rev Lett 2001; 87:266402. [PMID: 11800848 DOI: 10.1103/physrevlett.87.266402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2001] [Indexed: 05/23/2023]
Abstract
The critical electron density for the metal-insulator transition in a two-dimensional electron gas can be determined by two distinct methods: (i) a sign change of the temperature derivative of the resistance, and (ii) vanishing activation energy and vanishing nonlinearity of current-voltage characteristics as extrapolated from the insulating side. We find that, in zero magnetic field (but not in the presence of a parallel magnetic field), both methods give equivalent results, adding support to the existence of a true zero-field metal-insulator transition.
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Affiliation(s)
- A A Shashkin
- Physics Department, Northeastern University, Boston, Massachusetts 02115, USA
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29
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Shashkin AA, Kravchenko SV, Dolgopolov VT, Klapwijk TM. Indication of the ferromagnetic instability in a dilute two-dimensional electron system. Phys Rev Lett 2001; 87:086801. [PMID: 11497969 DOI: 10.1103/physrevlett.87.086801] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2001] [Indexed: 05/23/2023]
Abstract
The magnetic field B(c), in which the electrons become fully spin polarized, is found to be proportional to the deviation of the electron density from the zero-field metal-insulator transition in a two-dimensional electron system in silicon. The tendency of B(c) to vanish at a finite electron density suggests a ferromagnetic instability in this strongly correlated electron system.
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Affiliation(s)
- A A Shashkin
- Physics Department, Northeastern University, Boston, Massachusetts 02115, USA
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30
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Vitkalov SA, Zheng H, Mertes KM, Sarachik MP, Klapwijk TM. Scaling of the magnetoconductivity of silicon MOSFETs: evidence for a quantum phase transition in two dimensions. Phys Rev Lett 2001; 87:086401. [PMID: 11497966 DOI: 10.1103/physrevlett.87.086401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2000] [Revised: 05/08/2001] [Indexed: 05/23/2023]
Abstract
For a broad range of electron densities n and temperatures T, the in-plane magnetoconductivity of the two-dimensional system of electrons in silicon MOSFETs can be scaled onto a universal curve with a single parameter H(sigma)(n,T), where H(sigma) obeys the empirical relation H(sigma) = A(n) [Delta(n)(2)+T2](1/2). The characteristic energy k(B)Delta associated with the magnetic field dependence of the conductivity decreases with decreasing density, and extrapolates to 0 at a critical density n(0), signaling the approach to a zero-temperature quantum phase transition. We show that H(sigma) = AT for densities near n(0).
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Affiliation(s)
- S A Vitkalov
- Physics Department, City College of the City University of New York, New York, New York 10031, USA
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31
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Vitkalov SA, Zheng H, Mertes KM, Sarachik MP, Klapwijk TM. Small-angle shubnikov-de haas measurements in a 2D electron system: the effect of a strong In-plane magnetic field. Phys Rev Lett 2000; 85:2164-2167. [PMID: 10970488 DOI: 10.1103/physrevlett.85.2164] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2000] [Indexed: 05/23/2023]
Abstract
Measurements in magnetic fields applied at small angles relative to the electron plane in silicon MOSFETs indicate a factor of 2 increase of the frequency of Shubnikov-de Haas oscillations at H>H(sat). This signals the onset of full spin polarization above H(sat), the parallel field above which the resistivity saturates to a constant value. For H<H(sat), the phase of the second harmonic of the oscillations relative to the first is consistent with scattering events that depend on the overlap instead of the sum of the spin-up and spin-down densities of states. This unusual behavior may reflect the importance of many-body interactions.
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Affiliation(s)
- SA Vitkalov
- Physics Department, City College of the City University of New York, New York, New York 10031, USA
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32
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Kravchenko SV, Klapwijk TM. Metallic low-temperature resistivity in a 2D electron system over an extended temperature range. Phys Rev Lett 2000; 84:2909-2912. [PMID: 11018973 DOI: 10.1103/physrevlett.84.2909] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/1999] [Indexed: 05/23/2023]
Abstract
We report measurements of the zero-field resistivity in a dilute 2D electron system in silicon at temperatures down to 35 mK. This extends the previously explored range of temperatures in this system by almost an order of magnitude. On the metallic side, the resistivity near the metal-insulator transition continues to decrease with decreasing temperature and shows no low-temperature upturn. At the critical electron density, the resistivity is found to be temperature independent in the entire temperature range from 35 mK to 1 K.
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Affiliation(s)
- SV Kravchenko
- Physics Department, Northeastern University, Boston, Massachusetts 02115, USA
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33
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Kapteyn CM, Klapwijk TM, Borghs G. Transport in MultiTerminal Normal-Superconductor Devices: Reciprocity Relations, Negative and Nonlocal Resistances, and Reentrance of the Proximity Effect. Phys Rev Lett 1996; 77:4954-4957. [PMID: 10062676 DOI: 10.1103/physrevlett.77.4954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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34
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Kaesen KF, Huber A, Lorenz H, Kotthaus JP, Bakker S, Klapwijk TM. Quantum oscillation of the cyclotron mass in two-dimensional electron systems in silicon. Phys Rev B Condens Matter 1996; 54:1514-1517. [PMID: 9985986 DOI: 10.1103/physrevb.54.1514] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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35
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Kapteyn CM, Klapwijk TM, Borghs G. Sample-specific conductance fluctuations modulated by the superconducting phase. Phys Rev Lett 1996; 76:4592-4595. [PMID: 10061330 DOI: 10.1103/physrevlett.76.4592] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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36
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Magnée PH, Klapwijk TM, Borghs G. Experimental determination of the quasiparticle decay length xi qp in a diffusive superconducting quantum well. Phys Rev B Condens Matter 1995; 52:11630-11633. [PMID: 9980287 DOI: 10.1103/physrevb.52.r11630] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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37
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Meijer GI, Kuipers JJ, Klapwijk TM, Graaf W, Borghs G. Breakdown of the quantum Hall effect in InAs/AlSb quantum wells due to counterflowing edge channels. Phys Rev B Condens Matter 1995; 51:7973-7976. [PMID: 9977403 DOI: 10.1103/physrevb.51.7973] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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38
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Huber A, Lorenz H, Kotthaus JP, Bakker S, Klapwijk TM. Lateral n-i-p-i superlattices in Si metal-oxide-semiconductor structures. Phys Rev B Condens Matter 1995; 51:5028-5032. [PMID: 9979375 DOI: 10.1103/physrevb.51.5028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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39
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Magnée PH, Kooistra PH, Klapwijk TM. Enhanced conductance near zero voltage bias in mesoscopic superconductor-semiconductor junctions. Phys Rev B Condens Matter 1994; 50:4594-4599. [PMID: 9976765 DOI: 10.1103/physrevb.50.4594] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Bakker SJ, Klapwijk TM, Jaeger HM, Radelaar S. Observation of carrier-concentration-dependent reflectionless tunneling in a superconductor-two-dimensional-electron-gas-superconductor structure. Phys Rev B Condens Matter 1994; 49:13275-13278. [PMID: 10010258 DOI: 10.1103/physrevb.49.13275] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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42
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Heslinga DR, Shafranjuk SE, Klapwijk TM. Observation of double-gap-edge Andreev reflection at Si/Nb interfaces by point-contact spectroscopy. Phys Rev B Condens Matter 1994; 49:10484-10494. [PMID: 10009873 DOI: 10.1103/physrevb.49.10484] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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43
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Bakker SJ, Jaeger HM, Klapwijk TM, Radelaar S. Superconductivity and localization in thin polycrystalline tungsten-germanium films. Phys Rev B Condens Matter 1993; 48:4168-4171. [PMID: 10008877 DOI: 10.1103/physrevb.48.4168] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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44
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Heslinga DR, Klapwijk TM. Enhancement of superconductivity far above the critical temperature in double-barrier tunnel junctions. Phys Rev B Condens Matter 1993; 47:5157-5164. [PMID: 10006681 DOI: 10.1103/physrevb.47.5157] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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45
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Klapwijk TM, Heslinga DR. Carrier transport in mesoscopic silicon-coupled superconducting junctions. Phys Rev B Condens Matter 1993; 47:5170-5189. [PMID: 10006683 DOI: 10.1103/physrevb.47.5170] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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46
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Klapwijk TM, Suurmeijer EP. Critical temperature of thin niobium films on heavily doped silicon. Phys Rev B Condens Matter 1993; 47:5151-5156. [PMID: 10006680 DOI: 10.1103/physrevb.47.5151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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47
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48
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Magnée P, Klapwijk TM. Excess conductance of superconductor-semiconductor interfaces due to phase conjugation between electrons and holes. Phys Rev Lett 1992; 69:510-513. [PMID: 10046957 DOI: 10.1103/physrevlett.69.510] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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49
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Klapwijk TM. Nonequilibrium carrier transport in superconducting niobium-silicon heterostructures. Phys Rev B Condens Matter 1992; 45:535-538. [PMID: 10000223 DOI: 10.1103/physrevb.45.535] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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50
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