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Lu S, Nam H, Xiao P, Liu M, Guo Y, Bai Y, Cheng Z, Deng J, Li Y, Zhou H, Henkelman G, Fiete GA, Gao HJ, MacDonald AH, Zhang C, Shih CK. PTCDA Molecular Monolayer on Pb Thin Films: An Unusual π-Electron Kondo System and Its Interplay with a Quantum-Confined Superconductor. PHYSICAL REVIEW LETTERS 2021; 127:186805. [PMID: 34767397 DOI: 10.1103/physrevlett.127.186805] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 09/28/2021] [Indexed: 06/13/2023]
Abstract
The hybridization of magnetism and superconductivity has been an intriguing playground for correlated electron systems, hosting various novel physical phenomena. Usually, localized d or f electrons are central to magnetism. In this study, by placing a PTCDA (3,4,9,10-perylene tetracarboxylic dianhydride) molecular monolayer on ultrathin Pb films, we built a hybrid magnetism/superconductivity (M/SC) system consisting of only sp electronic levels. The magnetic moments reside in the unpaired molecular orbital originating from interfacial charge transfers. We reported distinctive tunneling spectroscopic features of such a Kondo screened π electron impurity lattice on a superconductor in the regime of T_{K}≫Δ, suggesting the formation of a two-dimensional bound states band. Moreover, moiré superlattices with tunable twist angle and the quantum confinement in the ultrathin Pb films provide easy and flexible implementations to tune the interplay between the Kondo physics and the superconductivity, which are rarely present in M/SC hybrid systems.
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Affiliation(s)
- Shuangzan Lu
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Hyoungdo Nam
- Department of Physics, the University of Texas at Austin, Austin, Texas 78712, USA
| | - Penghao Xiao
- Department of Chemistry, the University of Texas at Austin, Austin, Texas 78712, USA
- Department of Physics & Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H4J5, Canada
| | - Mengke Liu
- Department of Physics, the University of Texas at Austin, Austin, Texas 78712, USA
| | - Yanping Guo
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Yusong Bai
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Zhengbo Cheng
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Jinghao Deng
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Yanxing Li
- Department of Physics, the University of Texas at Austin, Austin, Texas 78712, USA
| | - Haitao Zhou
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Graeme Henkelman
- Department of Chemistry, the University of Texas at Austin, Austin, Texas 78712, USA
| | - Gregory A Fiete
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Hong-Jun Gao
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Allan H MacDonald
- Department of Physics, the University of Texas at Austin, Austin, Texas 78712, USA
| | - Chendong Zhang
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Chih-Kang Shih
- Department of Physics, the University of Texas at Austin, Austin, Texas 78712, USA
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2
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SPIDELL MATTHEWT, CONKLIN DAVISR, YUNG CHRISTOPHERS, THEOCHAROUS EVANGELOS, LEHMAN JOHNH. Spectral, spatial, and survivability evaluation of a flash-dried plasma-etched nanotube spray coating. APPLIED OPTICS 2019; 58:257-263. [PMID: 30645302 PMCID: PMC10949955 DOI: 10.1364/ao.58.000257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 12/03/2018] [Indexed: 06/09/2023]
Abstract
We demonstrate improved manufacturability of spectrally flat detectors for visible to mid-infrared wavelengths by characterizing a carbon nanotube spray coating compatible with lithium tantalate and other thermal sensors. Compared against previous spray coatings, it demonstrated the highest responsivity yet attained due to both higher absorptivity and thermal diffusivity, while also being matured to a commercially available product. It demonstrated spectral nonuniformity from 300 nm to 12 μm less than 1% with uncertainty (k=2) under 0.4%. The spatial nonuniformity of the assembled sensor was less than 0.5% over the central half (4 mm) of the absorber. As with previous developments employing isotropic carbon nanotube coatings, the absorber surface was sufficiently robust to withstand cleaning by compressed air blast and survived repeated vacuum cycling without measurable impact upon responsivity.
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Affiliation(s)
- MATTHEW T. SPIDELL
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - DAVIS R. CONKLIN
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - CHRISTOPHER S. YUNG
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | | | - JOHN H. LEHMAN
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
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3
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Yao F, Chen C, Liu C, Zhang J, Wang F, Liu K. High-Throughput Optical Imaging and Spectroscopy of One-Dimensional Materials. Chemistry 2017; 23:9703-9710. [PMID: 28378432 DOI: 10.1002/chem.201700731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Indexed: 11/07/2022]
Abstract
Direct visualization of one-dimensional (1D) materials under an optical microscope in ambient conditions is of great significance for their characterizations and applications. However, it is full of challenges to achieve such goal due to their relative small size (ca. 1 nm in diameter) in the optical-diffraction-limited laser spot (ca. 1 μm in diameter). In this Concept article, we introduce a polarization-based optical homodyne detection method that can be used as a general strategy to obtain high-throughput, real-time, optical imaging and in situ spectroscopy of polarization-inhomogeneous 1D materials. We will use carbon nanotubes (CNTs) as an example to demonstrate the applications of such characterization with respect to the absorption signal of individual nanotubes, real-time imaging of individual nanotubes in devices, and statistical structure information of nanotube arrays.
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Affiliation(s)
- Fengrui Yao
- State Key Laboratory for Mesoscopic Physics, School of Physics, Collaborative Innovation Center of Quantum Matter, Peking University, Beijing, 100871, P. R. China
| | - Cheng Chen
- State Key Laboratory for Mesoscopic Physics, School of Physics, Collaborative Innovation Center of Quantum Matter, Peking University, Beijing, 100871, P. R. China
| | - Can Liu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Collaborative Innovation Center of Quantum Matter, Peking University, Beijing, 100871, P. R. China
| | - Jin Zhang
- Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
| | - Feng Wang
- Department of Physics, University of California at Berkeley, Advanced Light Source Division and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Kaihui Liu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Collaborative Innovation Center of Quantum Matter, Peking University, Beijing, 100871, P. R. China
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4
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Han Q, Shan H, Deng J, Zhao A, Wang B, Hou JG. Construction of carbon-based two-dimensional crystalline nanostructure by chemical vapor deposition of benzene on Cu(111). NANOSCALE 2014; 6:7934-7939. [PMID: 24901493 DOI: 10.1039/c4nr00017j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A new carbon-based two-dimensional crystalline nanostructure was discovered. The nanostructure was facilely constructed by chemical vapor deposition of benzene on Cu(111) in an ultrahigh vacuum chamber. A low temperature scanning tunneling microscopy and spectroscopy study of the nanostructure indicated that it has an orthorhombic superstructure and a semiconductor character with an energy gap of 0.8 eV. An X-ray photoelectron spectroscopy study showed that C-C(sp(2)) bonding is predominantly preserved, suggesting a framework consisting of π-conjugated building blocks. The periodic nanostructure was found to be a surprisingly excellent template for isolating and stabilizing magnetic atoms: Co atoms deposited on it can be well dispersed and form locally ordered atomic chains with their atomic magnetism preserved. Therefore the nanostructure may be suitable for organic spintronic applications. The most likely structural model for the nanostructure is proposed with the aid of density functional theory calculations and simulations, suggesting that the 2D nanostructure may consist of polyphenylene chains interconnected by Cu adatoms.
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Affiliation(s)
- Qinghua Han
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, P.R.China.
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5
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Rossella F, Soldano C, Onorato P, Bellani V. Tuning electronic transport in cobalt-filled carbon nanotubes using magnetic fields. NANOSCALE 2014; 6:788-794. [PMID: 24257837 DOI: 10.1039/c3nr03856d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Metal-filled and decorated carbon nanotubes represent a class of quasi one-dimensional hybrid systems with enormous potential for applications in nanoelectronics and spintronics. Here we show that is possible to control the electrical conduction in ferromagnetic metal-filled carbon nanotubes by means of external magnetic fields, suggesting specific dimensionality-dependent conduction regimes. By increasing the magnetic field, we drive the charge flow from a positive to a negative magneto-conductance, revealing channel-selective conduction. Furthermore, the zero-field current temperature dependence shows different regimes, suggesting that the inter-shell hopping, assisted by the cobalt clusters, plays a key role in the dimensional crossover. The possibility of engineering and controlling the nature and size of the conducting shells and the filling with magnetic materials can allow the implementation of these systems in tunable hybrid nano-sensors and multifunctional magnetic devices.
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Affiliation(s)
- Francesco Rossella
- Dipartimento di Fisica, Università degli Studi di Pavia, Via Bassi 6, 27100 Pavia, Italy.
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6
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Schwabe A, Gütersloh D, Potthoff M. Competition between Kondo screening and indirect magnetic exchange in a quantum box. PHYSICAL REVIEW LETTERS 2012; 109:257202. [PMID: 23368491 DOI: 10.1103/physrevlett.109.257202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Indexed: 06/01/2023]
Abstract
Nanoscale systems of metal atoms antiferromagnetically exchange coupled to several magnetic impurities are shown to exhibit an unconventional reentrant competition between Kondo screening and indirect magnetic exchange interaction. Depending on the atomic positions of the magnetic moments, the total ground-state spin deviates from predictions of standard Ruderman-Kittel-Kasuya-Yosida perturbation theory. The effect shows up on an energy scale larger than the level width induced by the coupling to the environment and is experimentally accessible by studying magnetic field dependencies.
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Affiliation(s)
- Andrej Schwabe
- Institut für Theoretische Physik, Universität Hamburg, Jungiusstraße 9, 20355 Hamburg, Germany
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7
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Baruselli PP, Smogunov A, Fabrizio M, Tosatti E. Kondo effect of magnetic impurities in nanotubes. PHYSICAL REVIEW LETTERS 2012; 108:206807. [PMID: 23003169 DOI: 10.1103/physrevlett.108.206807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Indexed: 06/01/2023]
Abstract
Transition metal impurities will yield zero-bias anomalies in the conductance of well contacted metallic carbon nanotubes, but Kondo temperatures and geometry dependences have not been anticipated so far. Applying the density functional plus numerical renormalization group approach of Lucignano et al. to Co and Fe impurities in (4,4) and (8,8) nanotubes, we discover a huge difference of behavior between outside versus inside adsorption of the impurity. The predicted Kondo temperatures and zero-bias anomalies, tiny outside the nanotube, turn large and strongly radius dependent inside, owing to a change of symmetry of the magnetic orbital. Observation of this Kondo effect should open the way to a host of future experiments.
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Liu K, Deslippe J, Xiao F, Capaz RB, Hong X, Aloni S, Zettl A, Wang W, Bai X, Louie SG, Wang E, Wang F. An atlas of carbon nanotube optical transitions. NATURE NANOTECHNOLOGY 2012; 7:325-9. [PMID: 22504706 DOI: 10.1038/nnano.2012.52] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 03/14/2012] [Indexed: 05/12/2023]
Abstract
Electron-electron interactions are significantly enhanced in one-dimensional systems, and single-walled carbon nanotubes provide a unique opportunity for studying such interactions and the related many-body effects in one dimension. However, single-walled nanotubes can have a wide range of diameters and hundreds of different structures, each defined by its chiral index (n,m), where n and m are integers that can have values from zero up to 30 or more. Moreover, one-third of these structures are metals and two-thirds are semiconductors, and they display optical resonances at many different frequencies. Systematic studies of many-body effects in nanotubes would therefore benefit from the availability of a technique for identifying the chiral index of a nanotube based on a measurement of its optical resonances, and vice versa. Here, we report the establishment of a structure-property 'atlas' for nanotube optical transitions based on simultaneous electron diffraction measurements of the chiral index and Rayleigh scattering measurements of the optical resonances of 206 different single-walled nanotube structures. The nanotubes, which were suspended across open slit structures on silicon substrates, had diameters in the range 1.3-4.7 nm. We also use this atlas as a starting point for a systematic study of many-body effects in the excited states of single-walled nanotubes. We find that electron-electron interactions shift the optical resonance energies by the same amount for both metallic and semiconducting nanotubes, and that this shift (which corresponds to an effective Fermi velocity renormalization) increases monotonically with nanotube diameter. This behaviour arises from two sources: an intriguing cancellation of long-range electron-electron interaction effects, and the dependence of short-range electron-electron interactions on diameter.
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Affiliation(s)
- Kaihui Liu
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
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9
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Chorley SJ, Giavaras G, Wabnig J, Jones GAC, Smith CG, Briggs GAD, Buitelaar MR. Transport spectroscopy of an impurity spin in a carbon nanotube double quantum dot. PHYSICAL REVIEW LETTERS 2011; 106:206801. [PMID: 21668251 DOI: 10.1103/physrevlett.106.206801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Indexed: 05/30/2023]
Abstract
We make use of spin selection rules to investigate the electron spin system of a carbon nanotube double quantum dot. Measurements of the electron transport as a function of the magnetic field and energy detuning between the quantum dots reveal an intricate pattern of the spin state evolution. We demonstrate that the complete set of measurements can be understood by taking into account the interplay between spin-orbit interaction and a single impurity spin coupled to the double dot. The detection and tunability of this coupling are important for quantum manipulation in carbon nanotubes.
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Affiliation(s)
- S J Chorley
- Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom
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10
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Li Z, Li B, Yang J, Hou JG. Single-molecule chemistry of metal phthalocyanine on noble metal surfaces. Acc Chem Res 2010; 43:954-62. [PMID: 20359193 DOI: 10.1021/ar9001558] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To develop new functional materials and nanoscale electronics, researchers would like to accurately describe and precisely control the quantum state of a single molecule on a surface. Scanning tunneling microscopy (STM), combined with first-principles simulations, provides a powerful technique for acquiring this level of understanding. Traditionally, metal phthalocyanine (MPc) molecules, composed of a metal atom surrounded by a ligand ring, have been used as dyes and pigments. Recently, MPc molecules have shown great promise as components of light-emitting diodes, field-effect transistors, photovoltaic cells, and single-molecule devices. In this Account, we describe recent research on the characterization and control of adsorption and electronic states of a single MPc molecule on noble metal surfaces. In general, the electronic and magnetic properties of a MPc molecule largely depend on the type of metal ion within the phthalocyanine ligand and the type of surface on which the molecule is adsorbed. However, with the STM technique, we can use on-site molecular "surgery" to manipulate the structure and the properties of the molecule. For example, STM can induce a dehydrogenation reaction of the MPc, which allows us to control the Kondo effect, which describes the spin polarization of the molecule and its interaction with the complex environment. A specially designed STM tip can allow researchers to detect certain molecule-surface hybrid states that are not accessible by other techniques. By matching the local orbital symmetry of the STM tip and the molecule, we can generate the negative differential resistance effect in the formed molecular junction. This orbital symmetry based mechanism is extremely robust and does not critically depend on the geometry of the STM tip. In summary, this simple model system, a MPc molecule absorbed on a noble metal surface, demonstrates the power of STM for quantum characterization and manipulation of single molecules, highlighting the potential of this technique in a variety of applications.
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Affiliation(s)
- Zhenyu Li
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Bin Li
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Jinlong Yang
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Jian Guo Hou
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
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11
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Park WK, Greene LH. Andreev reflection and order parameter symmetry in heavy-fermion superconductors: the case of CeCoIn(5). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:103203. [PMID: 21817420 DOI: 10.1088/0953-8984/21/10/103203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We review the current status of Andreev reflection spectroscopy on the heavy fermions, mostly focusing on the case of CeCoIn(5), a heavy-fermion superconductor with a critical temperature of 2.3 K. This is a well-established technique to investigate superconducting order parameters via measurements of the differential conductance from nanoscale metallic junctions. Andreev reflection is clearly observed in CeCoIn(5) as in other heavy-fermion superconductors. Considering the large mismatch in Fermi velocities, this observation seemingly appears to disagree with the Blonder-Tinkham-Klapwijk (BTK) theory. The measured Andreev signal is highly reduced to the order of maximum ∼13% compared to the theoretically predicted value (100%). The background conductance exhibits a systematic evolution in its asymmetry over a wide temperature range from above the heavy-fermion coherence temperature down to well below the superconducting transition temperature. Analysis of the conductance spectra using the extended BTK model provides a qualitative measure for the superconducting order parameter symmetry, which is determined to be the d(x(2)-y(2)) wave in CeCoIn(5). It is found that existing models do not quantitatively account for the data, which we attribute to the intrinsic properties of the heavy fermions. A substantial body of experimental data and extensive theoretical analysis point to the existence of two-fluid components in CeCoIn(5) and other heavy-fermion compounds. A phenomenological model is proposed employing a Fano interference effect between two conductance channels in order to explain both the conductance asymmetry and the reduced Andreev signal. This model appears plausible not only because it provides good fits to the data but also because it is highly likely that the electrical conduction occurs via two channels, one into the heavy-electron liquid and the other into the conduction electron continuum. Further experimental and theoretical investigations will shed new light on the mechanism of how the coherent heavy-electron liquid emerges out of the Kondo lattice, a prototypical strongly correlated electron system. Unresolved issues and future directions are also discussed.
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Affiliation(s)
- W K Park
- Department of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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12
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Ternes M, Heinrich AJ, Schneider WD. Spectroscopic manifestations of the Kondo effect on single adatoms. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:053001. [PMID: 21817287 DOI: 10.1088/0953-8984/21/5/053001] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The present topical review focuses on recent advances concerning an intriguing phenomenon in condensed matter physics, the scattering of conduction electrons at the localized spin of a magnetic impurity: the Kondo effect. Spectroscopic signatures of this effect have been observed in the past by high-resolution photoemission which, however, has the drawback of averaging over a typical surface area of 1 mm(2). By combining the atomic-scale spatial resolution of the scanning tunneling microscope (STM) with an energy resolution of a few tens of µeV achievable nowadays in scanning tunneling spectroscopy (STS), and by exposing the magnetic adatom to external magnetic fields, our understanding of the interaction of a single magnetic impurity with the conduction electrons of the nonmagnetic host has been considerably deepened. New insight has emerged by taking advantage of quantum size effects in the metallic support and by decoupling the magnetic adatom from the supporting host metal, for instance by embedding it inside a molecule or by separating it by an ultrathin insulating film from the metal surface. In this way, Kondo resonances and Kondo temperatures can be tailored and manipulated by changing the local density of states of the environment. In the weak coupling limit between a Kondo impurity and a superconductor only a convolution of tip and sample DOS is observed while for strongly coupled systems midgap states appear, indicating superconducting pair breaking. Magnetic impurities with co-adsorbed hydrogen on metallic surfaces show pseudo-Kondo resonances owing to very low-energy vibrational excitations detected by inelastic tunneling spectroscopy. One of the most recent achievements in the field has been the clarification of the role of magnetic anisotropy in the Kondo effect for localized spin systems with a spin larger than S = 1/2.
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Affiliation(s)
- Markus Ternes
- IBM Almaden Research Center, 650 Harry Road, San Jose, CA, USA. Institut de Physique des Nanostructures, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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13
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Soldano C, Kar S, Talapatra S, Nayak S, Ajayan PM. Detection of nanoscale magnetic activity using a single carbon nanotube. NANO LETTERS 2008; 8:4498-4505. [PMID: 19367805 DOI: 10.1021/nl802456t] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The ultimate conductometric sensor for ferromagnetic activity of nanoscale magnetic materials could be a single carbon nanotube. We show that the electrical conductance of an individual carbon nanotube is sensitive to magnetic transitions of nanoscale magnets embedded inside it. To establish this, multiwall carbon nanotubes were impregnated with cobalt nanoclusters. Temperature dependence of conductance (5 K < T <300 K) of these nanotubes shows the usual Lüttinger-liquid power law behavior at higher temperatures and an onset of Coulomb blockade at lower temperatures. At the lowest temperature (T approximately 6 K), the differential conductance (dI/dV versus V) develops aperiodic fluctuations under an external magnetic field B, the rms amplitude of which grows with the magnitude of the field itself. Low-temperature magnetoconductance, studied as function of temperature and bias, can be interpreted in terms of weak antilocalization effects due to the presence of the magnetized clusters. The temperature dependence of magnetoconductance further presents a "peak"-like feature and slow dynamics around T =55 K, which depend on the magnitude and history of the applied B field. These observations indicate a sensitivity of electronic transport in the multiwall nanotubes to the dynamics of nanoscale magnets at low temperature.
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Affiliation(s)
- Caterina Soldano
- Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180, USA.
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14
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Huang P, Carter EA. Ab initio explanation of tunneling line shapes for the kondo impurity state. NANO LETTERS 2008; 8:1265-1269. [PMID: 18358009 DOI: 10.1021/nl0804203] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We report an ab initio study of the Kondo states formed from a Co adatom on Cu(111) and Cu(100). The model consists of a CoCun cluster ( n = 5-19) embedded in (111) and (100) Cu slabs. An embedding potential derived from density functional theory treats the interaction between the periodic crystal surroundings and the CoCun cluster, while strong electron correlations within CoCun are explicitly accounted for via configuration interaction (CI) methods. Analysis of the embedded CI wave function provides insight into the nature of the Kondo state, specifically into the influence of the crystal host on the Co d-electronic structure. We predict that different d-orbitals are preferentially singly occupied in Co on Cu(111) versus Cu(100) as a result of the different crystalline environment. We propose that these variations in the local d-electronic structure on Co, not accounted for in previous theories, are responsible for the drastically different Kondo resonance line shapes observed in scanning tunneling microscopy experiments on these two surfaces.
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Affiliation(s)
- Patrick Huang
- Department of Mechanical & Aerospace Engineering and Program in Applied & Computational Mathematics, Princeton University, Princeton, NJ 08544-5263, USA
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15
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Ohldag H, Tyliszczak T, Höhne R, Spemann D, Esquinazi P, Ungureanu M, Butz T. pi-electron ferromagnetism in metal-free carbon probed by soft x-ray dichroism. PHYSICAL REVIEW LETTERS 2007; 98:187204. [PMID: 17501606 DOI: 10.1103/physrevlett.98.187204] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Revised: 12/29/2006] [Indexed: 05/15/2023]
Abstract
Elemental carbon represents a fundamental building block of matter and the possibility of ferromagnetic order in carbon has attracted widespread attention. However, the origin of magnetic order in such a light element is only poorly understood and has puzzled researchers. We present a spectromicroscopy study at room temperature of proton irradiated metal-free carbon using the elemental and chemical specificity of x-ray magnetic circular dichroism. We demonstrate that the magnetic order in the investigated system originates only from the carbon pi-electron system.
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Affiliation(s)
- H Ohldag
- Stanford Synchrotron Radiation Laboratory, Stanford University, P.O. Box 20450, Menlo Park, California 94025, USA.
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16
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Chen YY, Huang PH, Ou MN, Wang CR, Yao YD, Lee TK, Ho MY, Lawrence JM, Booth CH. Kondo interactions and magnetic correlations in CePt2 nanocrystals. PHYSICAL REVIEW LETTERS 2007; 98:157206. [PMID: 17501380 DOI: 10.1103/physrevlett.98.157206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Indexed: 05/15/2023]
Abstract
The evolution of the Kondo effect and antiferromagnetic (AF) correlations with size reduction in CePt2 nanoparticles (3.1-26 nm) is studied by analysis of the temperature-dependent specific heat and magnetic susceptibility. The AF correlations diminish with size reduction. The Kondo effect predominates at small particle size with trivalent, small Kondo temperature (TK) magnetic regions coexisting with strongly mixed-valent, large TK nonmagnetic regions. We discuss the role of structural disorder, background density of states and the electronic quantum size effect on the results.
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Affiliation(s)
- Y Y Chen
- Institute of Physics, Academia Sinica, Taipei, Taiwan, Republic of China.
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17
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Hand T, Kroha J, Monien H. Spin correlations and finite-size effects in the one-dimensional kondo box. PHYSICAL REVIEW LETTERS 2006; 97:136604. [PMID: 17026060 DOI: 10.1103/physrevlett.97.136604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Indexed: 05/12/2023]
Abstract
We analyze the Kondo effect of a magnetic impurity attached to an ultrasmall metallic wire using the density matrix renormalization group. The spatial spin correlation function and the impurity spectral density are computed for system sizes of up to L=511 sites, covering the crossover from L<l{K} to L>l{K}, with l{K} the spin screening length. We establish a proportionality between the weight of the Kondo resonance and l{K} as a function of L. This suggests a spectroscopic way of detecting the Kondo cloud.
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Affiliation(s)
- Thomas Hand
- Physikalisches Institut, Universität Bonn, Nussallee 12, 53115 Bonn, Germany
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18
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Costa AT, Bose S, Omar Y. Entanglement of two impurities through electron scattering. PHYSICAL REVIEW LETTERS 2006; 96:230501. [PMID: 16803358 DOI: 10.1103/physrevlett.96.230501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2005] [Revised: 03/01/2006] [Indexed: 05/10/2023]
Abstract
We study how two magnetic impurities embedded in a solid can be entangled by an injected electron scattering between them and by subsequent measurement of the electron's state. We start by investigating an ideal case where only the electronic spin interacts successively through the same unitary operation with the spins of the two impurities. We find conditions for the impurity spins to be maximally entangled with a significant success probability. We then consider a more realistic description which includes both the forward and backscattering amplitudes. In this scenario, we obtain the entanglement between the impurities as a function of the interaction strength of the electron-impurity coupling. We find that our scheme allows us to entangle the impurities maximally with a significant probability.
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Affiliation(s)
- A T Costa
- Departamento de Ciências Exatas, Universidade Federal de Lavras, 37200-000 Lavras, Brazil
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19
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Huang P, Carter EA. Local electronic structure around a single Kondo impurity. NANO LETTERS 2006; 6:1146-50. [PMID: 16771570 DOI: 10.1021/nl0602847] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The local electronic structure due to the adsorption of Co on Cu111 is studied using an embedded cluster model, in which the crystal background is taken into account via an effective density functional theory (DFT)-based potential. This approach goes beyond the usual single-impurity Anderson model, where the ground state consists of a singly occupied impurity whose moment is compensated by the background conduction electrons. Ab initio correlated wave function calculations for the embedded cluster provide an alternative picture for this ground state and indicate that the quenching of the Co magnetic moment is due to the formation of metal-metal bonds with the Cu substrate. Low-lying excitations are also studied within the embedding model, and our results are discussed in the context of scanning tunneling microscopy experiments (Manoharan, H. C.; Lutz, C. P.; Eigler, D. M. Nature 2000, 403, 512), which find a sharp tunneling resonance localized in the vicinity of the Co adatom.
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Affiliation(s)
- Patrick Huang
- Department of Mechanical & Aerospace Engineering and Program in Applied & Computational Mathematics, Princeton University, Princeton, New Jersey 08544-5263, USA
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Zhao A, Li Q, Chen L, Xiang H, Wang W, Pan S, Wang B, Xiao X, Yang J, Hou JG, Zhu Q. Controlling the Kondo Effect of an Adsorbed Magnetic Ion Through Its Chemical Bonding. Science 2005; 309:1542-4. [PMID: 16141069 DOI: 10.1126/science.1113449] [Citation(s) in RCA: 284] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We report that the Kondo effect exerted by a magnetic ion depends on its chemical environment. A cobalt phthalocyanine molecule adsorbed on an Au111 surface exhibited no Kondo effect. Cutting away eight hydrogen atoms from the molecule with voltage pulses from a scanning tunneling microscope tip allowed the four orbitals of this molecule to chemically bond to the gold substrate. The localized spin was recovered in this artificial molecular structure, and a clear Kondo resonance was observed near the Fermi surface. We attribute the high Kondo temperature (more than 200 kelvin) to the small on-site Coulomb repulsion and the large half-width of the hybridized d-level.
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Affiliation(s)
- Aidi Zhao
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China (USTC), Hefei, Anhui 230026, People's Republic of China
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22
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Wang F, Dukovic G, Brus LE, Heinz TF. The Optical Resonances in Carbon Nanotubes Arise from Excitons. Science 2005; 308:838-41. [PMID: 15879212 DOI: 10.1126/science.1110265] [Citation(s) in RCA: 456] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Optical transitions in carbon nanotubes are of central importance for nanotube characterization. They also provide insight into the nature of excited states in these one-dimensional systems. Recent work suggests that light absorption produces strongly correlated electron-hole states in the form of excitons. However, it has been difficult to rule out a simpler model in which resonances arise from the van Hove singularities associated with the one-dimensional band [corrected] structure of the nanotubes. Here, two-photon excitation spectroscopy bolsters the exciton picture. We found binding energies of approximately 400 millielectron volts for semiconducting single-walled nanotubes with 0.8-nanometer diameters. The results demonstrate the dominant role of many-body interactions in the excited-state properties of one-dimensional systems.
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Affiliation(s)
- Feng Wang
- Departments of Physics and Electrical Engineering, Columbia University, 538 West 120th Street, New York, NY 10027, USA
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Ferretti A, Calzolari A, Di Felice R, Manghi F, Caldas MJ, Buongiorno Nardelli M, Molinari E. First-principles theory of correlated transport through nanojunctions. PHYSICAL REVIEW LETTERS 2005; 94:116802. [PMID: 15903879 DOI: 10.1103/physrevlett.94.116802] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2004] [Indexed: 05/02/2023]
Abstract
We report the inclusion of electron-electron correlation in the calculation of transport properties within an ab initio scheme. A key step is the reformulation of Landauer's approach in terms of an effective transmittance for the interacting electron system. We apply this framework to analyze the effect of short-range interactions on Pt atomic wires and discuss the coherent and incoherent correction to the mean-field approach.
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Affiliation(s)
- A Ferretti
- INFM National Center on nanoStructures and bioSystems at Surfaces (S3) and Dipartimento di Fisica, Università di Modena e Reggio Emilia, 41100 Modena, Italy
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24
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Savkin VV, Rubtsov AN, Katsnelson MI, Lichtenstein AI. Correlated adatom trimer on a metal surface: a continuous-time quantum Monte Carlo study. PHYSICAL REVIEW LETTERS 2005; 94:026402. [PMID: 15698201 DOI: 10.1103/physrevlett.94.026402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2004] [Indexed: 05/24/2023]
Abstract
The problem of three interacting Kondo impurities is solved within a numerically exact continuous-time quantum Monte Carlo scheme. A suppression of the Kondo resonance by interatomic exchange interactions for different cluster geometries is investigated. It is shown that a drastic difference between the Heisenberg and Ising cases appears for antiferromagnetically coupled adatoms. The effects of magnetic frustrations in the adatom trimer are investigated, and possible connections with available experimental data are discussed.
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Affiliation(s)
- V V Savkin
- Institute of Molecules and Materials, University of Nijmegen, 6525 ED Nijmegen, The Netherlands.
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Zhang X, Ju W, Gu M, Meng X, Shi W, Zhang X, Lee S. A facile route to fabrication of inorganic–small organic molecule cable-like nanocomposite arrays. Chem Commun (Camb) 2005:4202-4. [PMID: 16100603 DOI: 10.1039/b506459g] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel and facile method is reported for the preparation of silver iodide-small organic molecule (SOM) cable-like nanocomposites arrays, which involved first the fabrication of SOM nanotubes inside an anodic aluminium oxide (AAO) membrane, and then using the SOM nanotubes in AAO as secondary template to prepare the AgI nanowires in aqueous solution at room temperature.
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Affiliation(s)
- Xiujuan Zhang
- Technical Institute of Physics and Chemistry, Chinese Academy of Science, Beijing 100101, China.
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26
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Hashimoto A, Yorimitsu H, Ajima K, Suenaga K, Isobe H, Miyawaki J, Yudasaka M, Iijima S, Nakamura E. Selective deposition of a gadolinium(III) cluster in a hole opening of single-wall carbon nanohorn. Proc Natl Acad Sci U S A 2004; 101:8527-30. [PMID: 15163794 PMCID: PMC423227 DOI: 10.1073/pnas.0400596101] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Selective synthesis of particles of angstrom to nanometer size consisting of one to many metal atoms is instrumental in various applications, but it has been hampered by the tendency of the metal atom to form large clusters. We found, as studied by the state-of-the-art electron microscopic technique, a strategy to produce metal-containing nanoparticles isolated from each other by depositing metal atoms in a hydrophilic hole on or in the interior of a carbon nanotube as demonstrated by the reaction of Gd(OAc)(3) with oxidized single-wall nanohorns. Besides the potential utilities of the deposited metal clusters, the metal deposition protocol provides a method to control permeation of molecules through such openings.
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Affiliation(s)
- Ayako Hashimoto
- Research Center for Advanced Carbon Materials, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
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27
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Clougherty DP. Endohedral impurities in carbon nanotubes. PHYSICAL REVIEW LETTERS 2003; 90:035507. [PMID: 12570507 DOI: 10.1103/physrevlett.90.035507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2002] [Indexed: 05/24/2023]
Abstract
A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value. The effective potential is found to have O(2) symmetry, in agreement with numerical calculations. For metallic zigzag nanotubes endohedrally doped with transition metals in the dilute limit, the low-energy properties of the system may display two-channel Kondo behavior; however, strong vibronic coupling is seen to exponentially suppress the Kondo energy scale.
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Affiliation(s)
- Dennis P Clougherty
- Department of Physics, University of Vermont, Burlington, Vermont 05405-0125, USA.
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28
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Ouyang M, Huang JL, Lieber CM. Scanning tunneling microscopy studies of the one-dimensional electronic properties of single-walled carbon nanotubes. Annu Rev Phys Chem 2002; 53:201-20. [PMID: 11972007 DOI: 10.1146/annurev.physchem.53.091801.092924] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Recent developments in scanning tunneling microscopy studies of the electronic properties of single-walled carbon nanotubes are reviewed. A broad range of topics focused on the unique electronic properties of nanotubes are discussed, including (a) the underlying theoretical description of the electronic properties of nanotubes; (b) the roles of finite curvature and broken symmetries in perturbing electronic properties; (c) the unique one-dimensional energy dispersion in nanotubes; (d) the nature of end states; (e) quantum size effects in short tubes; (f) the interactions between local spins and carriers in metallic systems (the Kondo effect); and (g) the atomic structure and electronic properties of intramolecular junctions. The implications of these studies for understanding fundamental one-dimensional physics and future nanotube device applications are discussed.
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Affiliation(s)
- Min Ouyang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
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Kolesnychenko OY, de Kort R, Katsnelson MI, Lichtenstein AI, van Kempen H. Real-space imaging of an orbital Kondo resonance on the Cr(001) surface. Nature 2002; 415:507-9. [PMID: 11823854 DOI: 10.1038/415507a] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Kondo effect is usually connected with the interaction between a localized spin moment and itinerant electrons. This interaction leads to the formation of a narrow resonance at the Fermi level, which is called the Abrikosov-Suhl or Kondo resonance. Scanning tunnelling microscopy is an ideal technique for real-space investigations of complicated electronic structures and many-body phenomena, such as the formation of the Kondo resonance or d-wave pairing in high-T(c) superconductors. Theory has predicted that similar, Kondo-like many-electron resonances are possible for scattering centres with orbital instead of spin degrees of freedom--the quadruple momenta in uranium-based compounds or two-level systems in metallic glasses are examples of such 'pseudo-Kondo' scattering centres. Here we present evidence for the orbital Kondo resonance on a transition-metal surface. Investigations of an atomically clean Cr(001) surface at low temperature using scanning tunnelling microscopy reveal a very narrow resonance at 26 meV above the Fermi level, and enable us to visualize the orbital character of the corresponding state. The experimental data, together with many-body calculations, demonstrate that the observed resonance is an orbital Kondo resonance formed by two degenerate d(xz), d(yz) surface states.
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Affiliation(s)
- O Yu Kolesnychenko
- Research Institute for Materials, University of Nijmegen, The Netherlands
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Costa AT, Bose S. Impurity scattering induced entanglement of ballistic electrons. PHYSICAL REVIEW LETTERS 2001; 87:277901. [PMID: 11800916 DOI: 10.1103/physrevlett.87.277901] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2001] [Indexed: 05/23/2023]
Abstract
We show how entanglement between two conduction electrons is generated in the presence of a localized magnetic impurity embedded in an otherwise ballistic conductor of special geometry. This process is a generalization of beam-splitter mediated entanglement generation schemes with a localized spin placed at the site of the beam splitter. Our entangling scheme is unconditional and robust to randomness of the initial state of the impurity. The entangled state generated manifests itself in noise reduction of spin-dependent currents.
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Affiliation(s)
- A T Costa
- Center for Quantum Computation, University of Oxford, Clarendon Laboratory, Parks Road, OX1 3PU Oxford, United Kingdom.
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