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Kim SW, Conway LJ, Pickard CJ, Pascut GL, Monserrat B. Microscopic theory of colour in lutetium hydride. Nat Commun 2023; 14:7360. [PMID: 37963870 PMCID: PMC10646004 DOI: 10.1038/s41467-023-42983-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 10/25/2023] [Indexed: 11/16/2023] Open
Abstract
Nitrogen-doped lutetium hydride has recently been proposed as a near-ambient-conditions superconductor. Interestingly, the sample transforms from blue to pink to red as a function of pressure, but only the pink phase is claimed to be superconducting. Subsequent experimental studies have failed to reproduce the superconductivity, but have observed pressure-driven colour changes including blue, pink, red, violet, and orange. However, discrepancies exist among these experiments regarding the sequence and pressure at which these colour changes occur. Given the claimed relationship between colour and superconductivity, understanding colour changes in nitrogen-doped lutetium hydride may hold the key to clarifying the possible superconductivity in this compound. Here, we present a full microscopic theory of colour in lutetium hydride, revealing that hydrogen-deficient LuH2 is the only phase which exhibits colour changes under pressure consistent with experimental reports, with a sequence blue-violet-pink-red-orange. The concentration of hydrogen vacancies controls the precise sequence and pressure of colour changes, rationalising seemingly contradictory experiments. Nitrogen doping also modifies the colour of LuH2 but it plays a secondary role compared to hydrogen vacancies. Therefore, we propose hydrogen-deficient LuH2 as the key phase for exploring the superconductivity claim in the lutetium-hydrogen system. Finally, we find no phonon-mediated superconductivity near room temperature in the pink phase.
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Affiliation(s)
- Sun-Woo Kim
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK.
| | - Lewis J Conway
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK
- Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, 980-8577, Japan
| | - Chris J Pickard
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK
- Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, 980-8577, Japan
| | - G Lucian Pascut
- MANSiD Research Center and Faculty of Forestry, Stefan Cel Mare University (USV), Suceava, 720229, Romania
| | - Bartomeu Monserrat
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK.
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge, CB3 0HE, UK.
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2
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Römling ALE, Vivas-Viaña A, Muñoz CS, Kamra A. Resolving Nonclassical Magnon Composition of a Magnetic Ground State via a Qubit. PHYSICAL REVIEW LETTERS 2023; 131:143602. [PMID: 37862662 DOI: 10.1103/physrevlett.131.143602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 08/29/2023] [Indexed: 10/22/2023]
Abstract
Recently gained insights into equilibrium squeezing and entanglement harbored by magnets point toward exciting opportunities for quantum science and technology, while concrete protocols for exploiting these are needed. Here, we theoretically demonstrate that a direct dispersive coupling between a qubit and a noneigenmode magnon enables detecting the magnonic number states' quantum superposition that forms the ground state of the actual eigenmode-squeezed magnon-via qubit excitation spectroscopy. Furthermore, this unique coupling is found to enable control over the equilibrium magnon squeezing and a deterministic generation of squeezed even Fock states via the qubit state and its excitation. Our work demonstrates direct dispersive coupling to noneigenmodes, realizable in spin systems, as a general pathway to exploiting the equilibrium squeezing and related quantum properties thereby motivating a search for similar realizations in other platforms.
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Affiliation(s)
- Anna-Luisa E Römling
- Condensed Matter Physics Center (IFIMAC) and Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Alejandro Vivas-Viaña
- Condensed Matter Physics Center (IFIMAC) and Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Carlos Sánchez Muñoz
- Condensed Matter Physics Center (IFIMAC) and Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Akashdeep Kamra
- Condensed Matter Physics Center (IFIMAC) and Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
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3
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Liu S, Long M, Wang YP. Theoretical Study on the Raman Effect Due to Magnons in Two-Dimensional Magnets. NANO LETTERS 2023; 23:7427-7433. [PMID: 37549247 DOI: 10.1021/acs.nanolett.3c01851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/09/2023]
Abstract
Raman spectroscopy is one of the most useful experimental tools for studying elementary excitations in two-dimensional (2D) materials. The Raman scattering due to phonons was widely employed for detecting structural evolutions, especially those caused by magnetic phase transitions in 2D magnets. A first-principles theory of the Raman scattering effect caused by magnons is still lacking. We theoretically study the magnon Raman effect in 2D magnet CrI3. We propose a first-principles method and have calculated the intensity of circularly polarized Raman signals due to different magnon modes in the CrI3 monolayer and bilayers. The calculated Raman intensities due to magnons in the CrI3 monolayer and the rhombohedral bilayer are consistent with the selection rule deduced from the magnon pseudoangular moment and the parity of magnon modes. We also find that the selection rule is violated in the symmetry-broken monoclinic bilayer due to interlayer coupling.
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Affiliation(s)
- Shuang Liu
- School of Physics and Electronics, Hunan Key Laboratory for Super-microstructure and Ultrafast Process, Central South University, 932 South Lushan Road, Changsha 410083, People's Republic of China
| | - Mengqiu Long
- School of Physics and Electronics, Hunan Key Laboratory for Super-microstructure and Ultrafast Process, Central South University, 932 South Lushan Road, Changsha 410083, People's Republic of China
| | - Yun-Peng Wang
- School of Physics and Electronics, Hunan Key Laboratory for Super-microstructure and Ultrafast Process, Central South University, 932 South Lushan Road, Changsha 410083, People's Republic of China
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4
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Gentry C, Liao CT, You W, Ryan SA, Varner BA, Shi X, Guan MX, Gray T, Temple D, Meng S, Raschke M, Rossnagel K, Kapteyn HC, Murnane MM, Cating-Subramanian E. Super-resolved time–frequency measurements of coupled phonon dynamics in a 2D quantum material. Sci Rep 2022; 12:19734. [DOI: 10.1038/s41598-022-22055-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 10/10/2022] [Indexed: 11/18/2022] Open
Abstract
AbstractMethods to probe and understand the dynamic response of materials following impulsive excitation are important for many fields, from materials and energy sciences to chemical and neuroscience. To design more efficient nano, energy, and quantum devices, new methods are needed to uncover the dominant excitations and reaction pathways. In this work, we implement a newly-developed superlet transform—a super-resolution time-frequency analytical method—to analyze and extract phonon dynamics in a laser-excited two-dimensional (2D) quantum material. This quasi-2D system, 1T-TaSe2, supports both equilibrium and metastable light-induced charge density wave (CDW) phases mediated by strongly coupled phonons. We compare the effectiveness of the superlet transform to standard time-frequency techniques. We find that the superlet transform is superior in both time and frequency resolution, and use it to observe and validate novel physics. In particular, we show fluence-dependent changes in the coupled dynamics of three phonon modes that are similar in frequency, including the CDW amplitude mode, that clearly demonstrate a change in the dominant charge-phonon couplings. More interestingly, the frequencies of the three phonon modes, including the strongly-coupled CDW amplitude mode, remain time- and fluence-independent, which is unusual compared to previously investigated materials. Our study opens a new avenue for capturing the coherent evolution and couplings of strongly-coupled materials and quantum systems.
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5
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Huang KW, Wu Y, Si LG. Parametric-amplification-induced nonreciprocal magnon laser. OPTICS LETTERS 2022; 47:3311-3314. [PMID: 35776613 DOI: 10.1364/ol.459917] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/14/2022] [Indexed: 06/15/2023]
Abstract
We theoretically propose a scheme to achieve all-optical nonreciprocal magnon lasing action in a composite cavity optomagnonical system considering of a yttrium iron garnet sphere coupled to a parametric resonator. The magnon lasing behavior can be engendered via the magnon-induced Brillouin scattering process in the cavity optomagnonical system. By unidirectionally driving the χ(2)-nonlinear resonator with a classical coherent field, the squeezed effect occurs only in the selected direction due to the phase-matching condition, resulting in asymmetric detuning between the two resonators, which is the physical mechanism to generate a nonreciprocal magnon laser. We further examine the gain factor and power threshold of the magnon laser. Moreover, the isolation rate can reach 21 dB by adjusting the amplitude of the parametric amplification. Our work shows a path to obtain an all-optical nonreciprocal magnon laser, which provides a means for the preparation of a coherent magnon laser and laser protection.
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6
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Formisano F, Dubrovin RM, Pisarev RV, Kalashnikova AM, Kimel AV. Laser-induced THz magnetism of antiferromagnetic CoF 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:225801. [PMID: 35263728 DOI: 10.1088/1361-648x/ac5c20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 02/28/2022] [Indexed: 06/14/2023]
Abstract
Excitation, detection, and control of coherent THz magnetic excitation in antiferromagnets are challenging problems that can be addressed using ever shorter laser pulses. We study experimentally excitation of magnetic dynamics at THz frequencies in an antiferromagnetic insulator CoF2by sub-10 fs laser pulses. Time-resolved pump-probe polarimetric measurements at different temperatures and probe polarizations reveal laser-induced transient circular birefringence oscillating at the frequency of 7.45 THz and present below the Néel temperature. The THz oscillations of circular birefringence are ascribed to oscillations of the magnetic moments of Co2+ions induced by the laser-driven coherentEgphonon mode via the THz analogue of the transverse piezomagnetic effect. It is also shown that the same pulse launches coherent oscillations of the magnetic linear birefringence at the frequency of 3.4 THz corresponding to the two-magnon mode. Analysis of the probe polarization dependence of the transient magnetic linear birefringence at the frequency of the two-magnon mode enables identifying its symmetry.
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Affiliation(s)
- F Formisano
- Institute for Molecules and Materials, Radboud University, 6571AJ Nijmegen, The Netherlands
| | | | - R V Pisarev
- Ioffe Institute, 194021 St. Petersburg, Russia
| | | | - A V Kimel
- Institute for Molecules and Materials, Radboud University, 6571AJ Nijmegen, The Netherlands
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7
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Wu YL, Yin X, Hasaien JZL, Tian ZY, Ding Y, Zhao J. On-site in situ high-pressure ultrafast pump-probe spectroscopy instrument. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:113002. [PMID: 34852544 DOI: 10.1063/5.0064071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 10/09/2021] [Indexed: 06/13/2023]
Abstract
We conceive and construct an on-site in situ high-pressure time-resolved ultrafast optical spectroscopy instrument that facilitates ultrafast pump-probe dynamics measurements under high pressure conditions. We integrate an ultrafast pump-probe spectroscopy system with a diamond anvil cell (DAC) system. Significantly, both the DAC and the sample are fixed within the light path without motion and rotation throughout the whole ultrafast spectroscopy experiment, including tuning and calibrating the pressure. This instrument thus avoids introducing artifacts due to sample motion or rotation, enabling precision high-pressure ultrafast pump-probe dynamics investigations. As a demonstrating example, we compare the effect of on-site in situ conditions with off-site in situ conditions on the ultrafast dynamics of Sr2IrO4 under 0-44.5 GPa high pressure. Our data and analysis show that conventional possible artifacts are greatly reduced by using the on-site in situ layout. Our work helps the high-pressure ultrafast science investigation develop into a promising new area, which enables the exploration of nonequilibrium excited quantum states in the high-pressure regime.
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Affiliation(s)
- Y L Wu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - X Yin
- Center for High-Pressure Sciences and Technology Advanced Research, Beijing 100094, China
| | - J Z L Hasaien
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Z Y Tian
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yang Ding
- Center for High-Pressure Sciences and Technology Advanced Research, Beijing 100094, China
| | - Jimin Zhao
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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8
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Fabiani G, Bouman MD, Mentink JH. Supermagnonic Propagation in Two-Dimensional Antiferromagnets. PHYSICAL REVIEW LETTERS 2021; 127:097202. [PMID: 34506161 DOI: 10.1103/physrevlett.127.097202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 05/18/2021] [Accepted: 07/15/2021] [Indexed: 06/13/2023]
Abstract
We investigate the propagation of magnons after ultrashort perturbations of the exchange interaction in the prototype two-dimensional Heisenberg antiferromagnet. Using the recently proposed neural quantum states, we predict highly anisotropic spreading in space constrained by the symmetry of the perturbation. Interestingly, the propagation speed at the shortest length scale and timescale is up to 40% higher than the highest magnon velocity. We argue that the enhancement stems from extraordinary strong magnon-magnon interactions, suggesting new avenues for manipulating information transfer on ultrashort length scales and timescales.
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Affiliation(s)
- G Fabiani
- Radboud University, Institute for Molecules and Materials (IMM) Heyendaalseweg 135, 6525 AJ Nijmegen, Netherlands
| | - M D Bouman
- Radboud University, Institute for Molecules and Materials (IMM) Heyendaalseweg 135, 6525 AJ Nijmegen, Netherlands
| | - J H Mentink
- Radboud University, Institute for Molecules and Materials (IMM) Heyendaalseweg 135, 6525 AJ Nijmegen, Netherlands
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9
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Wang Z, Yuan HY, Cao Y, Li ZX, Duine RA, Yan P. Magnonic Frequency Comb through Nonlinear Magnon-Skyrmion Scattering. PHYSICAL REVIEW LETTERS 2021; 127:037202. [PMID: 34328762 DOI: 10.1103/physrevlett.127.037202] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 06/22/2021] [Indexed: 06/13/2023]
Abstract
An optical frequency comb consists of a set of discrete and equally spaced frequencies and has found wide applications in the synthesis over a broad range of spectral frequencies of electromagnetic waves and precise optical frequency metrology. Despite the analogies between magnons and photons in many aspects, the analog of an optical frequency comb in magnonic systems has not been reported. Here, we theoretically study the magnon-skyrmion interaction and find that a magnonic frequency comb (MFC) can be generated above a threshold driving amplitude, where the nonlinear scattering process involving three magnons prevails. The mode spacing of the MFC is equal to the breathing-mode frequency of the skyrmion and is thus tunable by either electric or magnetic means. The theoretical prediction is verified by micromagnetic simulations, and the essential physics can be generalized to a large class of magnetic solitons. Our findings open a new pathway to observe frequency comb structures in magnonic devices that may inspire the study of fundamental nonlinear physics in spintronic platforms in the future.
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Affiliation(s)
- Zhenyu Wang
- School of Electronic Science and Engineering and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - H Y Yuan
- Institute for Theoretical Physics, Utrecht University, 3584 CC Utrecht, Netherlands
| | - Yunshan Cao
- School of Electronic Science and Engineering and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Z-X Li
- School of Electronic Science and Engineering and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Rembert A Duine
- Institute for Theoretical Physics, Utrecht University, 3584 CC Utrecht, Netherlands
| | - Peng Yan
- School of Electronic Science and Engineering and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
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10
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Mertens F, Terschanski M, Mönkebüscher D, Ponzoni S, Bossini D, Cinchetti M. Wide spectral range ultrafast pump-probe magneto-optical spectrometer at low temperature, high-magnetic and electric fields. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:113001. [PMID: 33261465 DOI: 10.1063/5.0024449] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Accepted: 10/17/2020] [Indexed: 06/12/2023]
Abstract
We developed a table-top setup to perform magneto-optical pump-probe measurements with the possibility to independently tune the photon-energy of both pump and probe beams in the 0.5 eV-3.5 eV range. Our apparatus relies on a commercial turn-key amplified laser system, able to generate light pulses with duration shorter than or comparable to 100 fs throughout the whole spectral range. The repetition rate of the source can be modified via the computer in the 1 kHz to 1 MHz range. A commercial balanced detector is connected to a high-frequency digitizer, allowing for a highly-sensitive detection scheme: rotations of the probe polarization as small as 70 μdeg can be measured. Additionally, a DC magnetic field as high as 9 T and voltages in the kV regime can be applied on the sample. A cryostat allows us to precisely set the temperature of the specimen in the 4 K-420 K interval. We prove the performance of our setup by measuring the ultrafast demagnetization of a cobalt crystal as a function of a wide variety of experimental parameters.
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Affiliation(s)
- F Mertens
- Experimentelle Physik VI, TU Dortmund, Otto-Hahn-Straße 4, 44227 Dortmund, Germany
| | - M Terschanski
- Experimentelle Physik VI, TU Dortmund, Otto-Hahn-Straße 4, 44227 Dortmund, Germany
| | - D Mönkebüscher
- Experimentelle Physik VI, TU Dortmund, Otto-Hahn-Straße 4, 44227 Dortmund, Germany
| | - S Ponzoni
- Experimentelle Physik VI, TU Dortmund, Otto-Hahn-Straße 4, 44227 Dortmund, Germany
| | - D Bossini
- Experimentelle Physik VI, TU Dortmund, Otto-Hahn-Straße 4, 44227 Dortmund, Germany
| | - M Cinchetti
- Experimentelle Physik VI, TU Dortmund, Otto-Hahn-Straße 4, 44227 Dortmund, Germany
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11
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Yu BH, Tian ZY, Sun F, Peets DC, Bai XD, Feng DL, Zhao J. Ultrafast quasiparticle dynamics and coherent phonon in nodal line topological material LaBi. OPTICS EXPRESS 2020; 28:15855-15862. [PMID: 32549421 DOI: 10.1364/oe.383995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 04/21/2020] [Indexed: 06/11/2023]
Abstract
We use an ultrafast optical pump-probe spectroscopy to study quasiparticle (QP) dynamics in a topological insulator LaBi. Temperature-dependent optical measurements have been carried out, by which we observed nearly constant fast component (with a lifetime of 0.15 ps) and slow component (with a lifetime of 1.5 ps) for the whole range from 10 K to 295 K. The laser fluence dependence result shows that there is no saturation for the QP dynamics up to 3.3 mJ /cm2. Moreover, an Eg mode transverse optical (TO) coherent phonon has also been observed, with a frequency of 2.8 THz. Our results provide for the first time the ultrafast dynamics information of both the QPs and coherent phonons in a nodal line topological material.
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12
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Padmanabhan P, Sekiguchi F, Versteeg RB, Slivina E, Tsurkan V, Bordács S, Kézsmárki I, van Loosdrecht PHM. Optically Driven Collective Spin Excitations and Magnetization Dynamics in the Néel-type Skyrmion Host GaV_{4}S_{8}. PHYSICAL REVIEW LETTERS 2019; 122:107203. [PMID: 30932635 DOI: 10.1103/physrevlett.122.107203] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 02/08/2019] [Indexed: 06/09/2023]
Abstract
GaV_{4}S_{8} is a multiferroic semiconductor hosting magnetic cycloid (Cyc) and Néel-type skyrmion lattice (SkL) phases with a broad region of thermal and magnetic stability. Here, we use time-resolved magneto-optical Kerr spectroscopy to show the coherent generation of collective spin excitations in the Cyc and SkL phases. Our micromagnetic simulations reveal that these are driven by an optically induced modulation of uniaxial anisotropy. Our results shed light on spin dynamics in anisotropic materials hosting skyrmions and pave a new pathway for the optical manipulation of their magnetic order.
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Affiliation(s)
- P Padmanabhan
- Physics Institute II, University of Cologne, 50937 Cologne, Germany
| | - F Sekiguchi
- Physics Institute II, University of Cologne, 50937 Cologne, Germany
| | - R B Versteeg
- Physics Institute II, University of Cologne, 50937 Cologne, Germany
| | - E Slivina
- Physics Institute II, University of Cologne, 50937 Cologne, Germany
| | - V Tsurkan
- Institute of Applied Physics, MD 2028, Chisinau, Republic of Moldova
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86159 Augsburg, Germany
| | - S Bordács
- Department of Physics, Budapest University of Technology and Economics and MTA-BME Lendület Magneto-optical Spectroscopy Research Group, 1111 Budapest, Hungary
- Hungarian Academy of Sciences, Premium Postdoctoral Program, 1051 Budapest, Hungary
| | - I Kézsmárki
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86159 Augsburg, Germany
- Department of Physics, Budapest University of Technology and Economics and MTA-BME Lendület Magneto-optical Spectroscopy Research Group, 1111 Budapest, Hungary
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13
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Haghshenasfard Z, Cottam MG. Squeezing and time evolution of magnon states under perpendicular pumping. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:425802. [PMID: 30198857 DOI: 10.1088/1361-648x/aadfff] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The coherent magnon state representation is employed to investigate the quantum-statistical behavior of the nonlinear excitation of magnons in ferromagnets. Both the long-range magnetic dipole-dipole and short-range exchange interactions are included, along with a static longitudinal applied field and a microwave pumping field in the perpendicular orientation. Within a microscopic (or Hamiltonian-based) approach the total Hamiltonian is transformed from spin operators to a normal-mode set of boson creation and annihilation operators. When the three-magnon interactions are included, it is found that the microwave pumping field may be used to control the nonlinear statistical properties of the system. From a study of the time evolution of the system we deduce the average number of magnons, the super-Poissonian statistical behavior, and the occurrence of magnon squeezing. We also compare the results with the case where the microwave pumping field is in the parallel orientation, and it is found that there are important differences in the time dependence.
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Affiliation(s)
- Zahra Haghshenasfard
- Department of Physics and Astronomy, University of Western Ontario, London, Ontario, N6A 3K7, Canada
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14
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Owerre SA, Nsofini J. Squeezed Dirac and topological magnons in a bosonic honeycomb optical lattice. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:455802. [PMID: 29049033 DOI: 10.1088/1361-648x/aa8dcb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Quantum information storage using charge-neutral quasiparticles is expected to play a crucial role in the future of quantum computers. In this regard, magnons or collective spin-wave excitations in solid-state materials are promising candidates in the future of quantum computing. Here, we study the quantum squeezing of Dirac and topological magnons in a bosonic honeycomb optical lattice with spin-orbit interaction by utilizing the mapping to quantum spin-[Formula: see text] XYZ Heisenberg model on the honeycomb lattice with discrete Z2 symmetry and a Dzyaloshinskii-Moriya interaction. We show that the squeezed magnons can be controlled by the Z2 anisotropy and demonstrate how the noise in the system is periodically modified in the ferromagnetic and antiferromagnetic phases of the model. Our results also apply to solid-state honeycomb (anti)ferromagnetic insulators.
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Affiliation(s)
- S A Owerre
- Perimeter Institute for Theoretical Physics, 31 Caroline St. N.- Waterloo, Ontario N2L 2Y5, Canada
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15
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Mentink JH. Manipulating magnetism by ultrafast control of the exchange interaction. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:453001. [PMID: 28990577 DOI: 10.1088/1361-648x/aa8abf] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In recent years, the optical control of exchange interactions has emerged as an exciting new direction in the study of the ultrafast optical control of magnetic order. Here we review recent theoretical works on antiferromagnetic systems, devoted to (i) simulating the ultrafast control of exchange interactions, (ii) modeling the strongly nonequilibrium response of the magnetic order and (iii) the relation with relevant experimental works developed in parallel. In addition to the excitation of spin precession, we discuss examples of rapid cooling and the control of ultrafast coherent longitudinal spin dynamics in response to femtosecond optically induced perturbations of exchange interactions. These elucidate the potential for exploiting the control of exchange interactions to find new scenarios for both faster and more energy-efficient manipulation of magnetism.
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Affiliation(s)
- J H Mentink
- Radboud University Nijmegen, Institute for Molecules and Materials, Heijendaalseweg 135, 6525 AJ, Nijmegen, Netherlands
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16
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Papenkort T, Axt VM, Kuhn T. Stationary Phonon Squeezing by Optical Polaron Excitation. PHYSICAL REVIEW LETTERS 2017; 118:097401. [PMID: 28306296 DOI: 10.1103/physrevlett.118.097401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Indexed: 06/06/2023]
Abstract
We demonstrate that a stationary squeezed phonon state can be prepared by a pulsed optical excitation of a semiconductor quantum well. Unlike previously discussed scenarios for generating squeezed phonons, the corresponding uncertainties become stationary after the excitation and do not oscillate in time. The effect is caused by two-phonon correlations within the excited polaron. We demonstrate by quantum kinetic simulations and by a perturbation analysis that the energetically lowest polaron state comprises two-phonon correlations which, after the pulse, result in an uncertainty of the lattice momentum that is continuously lower than in the ground state of the semiconductor. The simulations show the dynamics of the polaron formation process and the resulting time-dependent lattice uncertainties.
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Affiliation(s)
- T Papenkort
- Institut für Festkörpertheorie, Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
| | - V M Axt
- Institut für Theoretische Physik III, Universität Bayreuth, 95440 Bayreuth, Germany
| | - T Kuhn
- Institut für Festkörpertheorie, Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
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17
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Haghshenasfard Z, Cottam MG. Quantum statistics and squeezing for a microwave-driven interacting magnon system. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:045803. [PMID: 27897145 DOI: 10.1088/1361-648x/29/4/045803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Theoretical studies are reported for the statistical properties of a microwave-driven interacting magnon system. Both the magnetic dipole-dipole and the exchange interactions are included and the theory is developed for the case of parallel pumping allowing for the inclusion of the nonlinear processes due to the four-magnon interactions. The method of second quantization is used to transform the total Hamiltonian from spin operators to boson creation and annihilation operators. By using the coherent magnon state representation we have studied the magnon occupation number and the statistical behavior of the system. In particular, it is shown that the nonlinearities introduced by the parallel pumping field and the four-magnon interactions lead to non-classical quantum statistical properties of the system, such as magnon squeezing. Also control of the collapse-and-revival phenomena for the time evolution of the average magnon number is demonstrated by varying the parallel pumping amplitude and the four-magnon coupling.
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Affiliation(s)
- Zahra Haghshenasfard
- Department of Physics and Astronomy, The University of Western Ontario, London, Ontario N6A 3K7, Canada
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18
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Tian YC, Zhang WH, Li FS, Wu YL, Wu Q, Sun F, Zhou GY, Wang L, Ma X, Xue QK, Zhao J. Ultrafast Dynamics Evidence of High Temperature Superconductivity in Single Unit Cell FeSe on SrTiO_{3}. PHYSICAL REVIEW LETTERS 2016; 116:107001. [PMID: 27015504 DOI: 10.1103/physrevlett.116.107001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Indexed: 06/05/2023]
Abstract
We report the time-resolved excited state ultrafast dynamics of single unit cell (1 UC) thick FeSe films on SrTiO_{3} (STO), with FeTe capping layers. By measuring the photoexcited quasiparticles' density and lifetime, we unambiguously identify a superconducting (SC) phase transition, with a transition temperature T_{c} of 68 (-5/+2) K and a SC gap of Δ(0)=20.2±1.5 meV. The obtained electron-phonon coupling strength λ is as large as 0.48, demonstrating the likely crucial role of electron-phonon coupling in the high temperature superconductivity of the 1 UC FeSe on STO systems. We further find a 0.05 THz coherent acoustic phonon branch in the capping layer, which provides an additional decay channel to the gluing bosons.
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Affiliation(s)
- Y C Tian
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - W H Zhang
- State Key Laboratory for Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
| | - F S Li
- State Key Laboratory for Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
| | - Y L Wu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Q Wu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - F Sun
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - G Y Zhou
- State Key Laboratory for Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
| | - Lili Wang
- State Key Laboratory for Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Xucun Ma
- State Key Laboratory for Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Qi-Kun Xue
- State Key Laboratory for Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Jimin Zhao
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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19
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Macrospin dynamics in antiferromagnets triggered by sub-20 femtosecond injection of nanomagnons. Nat Commun 2016; 7:10645. [PMID: 26847766 PMCID: PMC4748265 DOI: 10.1038/ncomms10645] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 01/06/2016] [Indexed: 11/09/2022] Open
Abstract
The understanding of how the sub-nanoscale exchange interaction evolves in macroscale correlations and ordered phases of matter, such as magnetism and superconductivity, requires to bridging the quantum and classical worlds. This monumental challenge has so far only been achieved for systems close to their thermodynamical equilibrium. Here we follow in real time the ultrafast dynamics of the macroscale magnetic order parameter in the Heisenberg antiferromagnet KNiF3 triggered by the impulsive optical generation of spin excitations with the shortest possible nanometre wavelength and femtosecond period. Our magneto-optical pump–probe experiments also demonstrate the coherent manipulation of the phase and amplitude of these femtosecond nanomagnons, whose frequencies are defined by the exchange energy. These findings open up opportunities for fundamental research on the role of short-wavelength spin excitations in magnetism and strongly correlated materials; they also suggest that nanospintronics and nanomagnonics can employ coherently controllable spin waves with frequencies in the 20 THz domain. Magnetic order in nature is defined by the exchange interaction, however its understanding on the ultrafast- and nanometer-scales is limited. Here, the authors follow the femtosecond sub-nanometer dynamics of the antiferromagnetic order parameter in KNiF3 triggered by photo-generated exchange magnons.
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20
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Double charge ordering states and spin ordering state observed in a RFe2O4 system. Sci Rep 2014; 4:6429. [PMID: 25234133 PMCID: PMC5377305 DOI: 10.1038/srep06429] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 09/02/2014] [Indexed: 11/08/2022] Open
Abstract
Charge, spin, and lattice degrees of orderings are of great interest in the layered quantum material RFe2O4 (R = Y, Er, Yb, Tm, and Lu) system. Recently many unique properties have been found using various experimental methods. However so far the nature of the two-dimensional (2D) charge ordering (CO) state is not clear and no observation of its fine structure in energy has been reported. Here we report unambiguous observation of double 2D CO states at relatively high temperature in a polycrystalline Er0.1Yb0.9Fe2O4 using Raman scattering. The energy gaps between the 3D and the double 2D states are 170 meV (41.2 THz) and 193 meV (46.6 THz), respectively. We also observed a spin ordering (SO) state at below 210 K with characteristic energy of 45 meV (10.7 THz). Our investigation experimentally identified new fine structures of quantum orders in the system, which also extends the capability of optical methods in investigating other layered quantum materials.
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21
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Ge S, Liu X, Qiao X, Wang Q, Xu Z, Qiu J, Tan PH, Zhao J, Sun D. Coherent longitudinal acoustic phonon approaching THz frequency in multilayer Molybdenum Disulphide. Sci Rep 2014; 4:5722. [PMID: 25031087 PMCID: PMC4101472 DOI: 10.1038/srep05722] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 06/24/2014] [Indexed: 11/09/2022] Open
Abstract
Coherent longitudinal acoustic phonon is generated and detected in multilayer Molybdenum Disulphide (MoS2) with number of layers ranging from 10 to over 1300 by femtosecond laser pulse. For thin MoS2, the excited phonon frequency exhibits a standing wave nature and shows linear dependence on the sample thickness. The frequency varies from 40 GHz to 0.2 THz (10 layers), which promises possible application in THz frequency mechanical resonators. This linear thickness dependence gradually disappears in thicker samples above about 150 layers, and the oscillation period shows linear dependence on the probe wavelength. From both the oscillation period of the coherent phonon and the delay time of acoustic echo, we can deduce a consistent sound velocity of 7.11*10(3) m/s in MoS2. The generation mechanisms of the coherent acoustic phonon are also discussed through pump power dependent measurement.
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Affiliation(s)
- Shaofeng Ge
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, P. R. China
| | - Xuefeng Liu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, P. R. China
| | - Xiaofen Qiao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, P. R. China
| | - Qinsheng Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, P. R. China
| | - Zhen Xu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, P. R. China
| | - Jun Qiu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, P. R. China
| | - Ping-Heng Tan
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083, P. R. China
| | - Jimin Zhao
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Dong Sun
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, P. R. China
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22
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Mansart B, Lorenzana J, Mann A, Odeh A, Scarongella M, Chergui M, Carbone F. Coupling of a high-energy excitation to superconducting quasiparticles in a cuprate from coherent charge fluctuation spectroscopy. Proc Natl Acad Sci U S A 2013; 110:4539-4544. [PMCID: PMC3606993 DOI: 10.1073/pnas.1218742110] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2024] Open
Abstract
Dynamical information on spin degrees of freedom of proteins or solids can be obtained by NMR and electron spin resonance. A technique with similar versatility for charge degrees of freedom and their ultrafast correlations could move the understanding of systems like unconventional superconductors forward. By perturbing the superconducting state in a high-T c cuprate, using a femtosecond laser pulse, we generate coherent oscillations of the Cooper pair condensate that can be described by an NMR/electron spin resonance formalism. The oscillations are detected by transient broad-band reflectivity and are found to resonate at the typical scale of Mott physics (2.6 eV), suggesting the existence of a nonretarded contribution to the pairing interaction, as in unconventional (non-Migdal–Eliashberg) theories.
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Affiliation(s)
- Barbara Mansart
- Laboratory for Ultrafast Microscopy and Electron Scattering, Institute of Condensed Matter Physics, and
- Laboratory of Ultrafast Spectroscopy, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland; and
| | - José Lorenzana
- Institute for Complex Systems–Consiglio Nazionale delle Ricerche, and Physics Department, University of Rome “La Sapienza,” I-00185 Rome, Italy
| | - Andreas Mann
- Laboratory for Ultrafast Microscopy and Electron Scattering, Institute of Condensed Matter Physics, and
| | - Ahmad Odeh
- Laboratory of Ultrafast Spectroscopy, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland; and
| | - Mariateresa Scarongella
- Laboratory of Ultrafast Spectroscopy, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland; and
| | - Majed Chergui
- Laboratory of Ultrafast Spectroscopy, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland; and
| | - Fabrizio Carbone
- Laboratory of Ultrafast Spectroscopy, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland; and
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23
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Kalashnikova AM, Kimel AV, Pisarev RV, Gridnev VN, Kirilyuk A, Rasing T. Impulsive generation of coherent magnons by linearly polarized light in the easy-plane antiferromagnet FeBO3. PHYSICAL REVIEW LETTERS 2007; 99:167205. [PMID: 17995288 DOI: 10.1103/physrevlett.99.167205] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2007] [Revised: 06/27/2007] [Indexed: 05/25/2023]
Abstract
Polarization-dependent excitation of coherent spin precession by 150 fs linearly polarized laser pulses is observed in the easy-plane antiferromagnet FeBO3. We show that the mechanism of excitation is impulsive stimulated Raman scattering. This process is shown to be determined not only by the magneto-optical constants of the material, but also by the properties of the spin precession itself. Though carrying no angular momentum, the linearly polarized laser pulses act on the spins as effective fields that can be considered as an ultrafast inverse Cotton-Mouton effect.
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Affiliation(s)
- A M Kalashnikova
- Institute for Molecules and Materials, Radboud University Nijmegen, 6525 ED Nijmegen, The Netherlands
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24
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Jun-ichi T, Keisuke M, Toshirou Y. Raman lasing and cascaded coherent anti-Stokes Raman scattering of a two-phonon Raman band. OPTICS LETTERS 2006; 31:1501-3. [PMID: 16642152 DOI: 10.1364/ol.31.001501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Raman lasing of a two-phonon Raman band in the anti-Stokes side is demonstrated. Two femtosecond light pulses with identical wavelengths are irradiated onto a SrTiO3 crystal in a cross-beam configuration. Under low excitation power, several wave-mixing signals with identical wavelengths are emitted. When the power exceeds a critical value, cascaded coherent anti-Stokes Raman scattering (CARS) signals are emitted, the frequency step of which is coincident with that of the strongest two-phonon Raman band of 2TO2.
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