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Shan WY. Gate-tunable circular phonon dichroism effect in bilayer graphene. iScience 2024; 27:109374. [PMID: 38510119 PMCID: PMC10951653 DOI: 10.1016/j.isci.2024.109374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 01/30/2024] [Accepted: 02/27/2024] [Indexed: 03/22/2024] Open
Abstract
Circular phonon dichroism effect has been proposed in two-dimensional materials; however, the lack of tunability hinders the exploration of the effect. Here, we investigate the role of dual-gating-induced inversion symmetry breaking in the circular phonon dichroism effect in bilayer graphene. We find that the introduction of inversion symmetry breaking modifies the response in the layer-symmetric and layer-antisymmetric channels, and results in the occurrence of phonon dichroism in the cross-channel. In the layer representation, the inversion symmetry breaking breaks the equality of intralayer circular phonon dichroism and enhances the interlayer response. Our results suggest that layer degree of freedom provides possibilities to tune phonon dynamics, which paves a way toward different physics and applications of two-dimensional acoustoelectronics and layertronics.
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Affiliation(s)
- Wen-Yu Shan
- Department of Physics, School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China
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2
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Basini M, Pancaldi M, Wehinger B, Udina M, Unikandanunni V, Tadano T, Hoffmann MC, Balatsky AV, Bonetti S. Terahertz electric-field-driven dynamical multiferroicity in SrTiO 3. Nature 2024; 628:534-539. [PMID: 38600387 PMCID: PMC11023939 DOI: 10.1038/s41586-024-07175-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 02/07/2024] [Indexed: 04/12/2024]
Abstract
The emergence of collective order in matter is among the most fundamental and intriguing phenomena in physics. In recent years, the dynamical control and creation of novel ordered states of matter not accessible in thermodynamic equilibrium is receiving much attention1-6. The theoretical concept of dynamical multiferroicity has been introduced to describe the emergence of magnetization due to time-dependent electric polarization in non-ferromagnetic materials7,8. In simple terms, the coherent rotating motion of the ions in a crystal induces a magnetic moment along the axis of rotation. Here we provide experimental evidence of room-temperature magnetization in the archetypal paraelectric perovskite SrTiO3 due to this mechanism. We resonantly drive the infrared-active soft phonon mode with an intense circularly polarized terahertz electric field and detect the time-resolved magneto-optical Kerr effect. A simple model, which includes two coupled nonlinear oscillators whose forces and couplings are derived with ab initio calculations using self-consistent phonon theory at a finite temperature9, reproduces qualitatively our experimental observations. A quantitatively correct magnitude was obtained for the effect by also considering the phonon analogue of the reciprocal of the Einstein-de Haas effect, which is also called the Barnett effect, in which the total angular momentum from the phonon order is transferred to the electronic one. Our findings show a new path for the control of magnetism, for example, for ultrafast magnetic switches, by coherently controlling the lattice vibrations with light.
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Affiliation(s)
- M Basini
- Department of Physics, Stockholm University, Stockholm, Sweden
| | - M Pancaldi
- Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, Venice, Italy
- Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
| | - B Wehinger
- Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, Venice, Italy
- European Synchrotron Radiation Facility, Grenoble, France
| | - M Udina
- Department of Physics and ISC-CNR, 'Sapienza' University of Rome, Rome, Italy
| | - V Unikandanunni
- Department of Physics, Stockholm University, Stockholm, Sweden
| | - T Tadano
- Research Center for Magnetic and Spintronic Materials, National Institute for Materials Science, Tsukuba, Japan
| | - M C Hoffmann
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - A V Balatsky
- Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, Venice, Italy
- NORDITA, Stockholm, Sweden
- Department of Physics, University of Connecticut, Storrs, CT, USA
- Rara Foundation - Sustainable Materials and Technologies, Venice, Italy
| | - S Bonetti
- Department of Physics, Stockholm University, Stockholm, Sweden.
- Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, Venice, Italy.
- Rara Foundation - Sustainable Materials and Technologies, Venice, Italy.
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3
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Lujan D, Choe J, Chaudhary S, Ye G, Nnokwe C, Rodriguez-Vega M, He J, Gao FY, Nunley TN, Baldini E, Zhou J, Fiete GA, He R, Li X. Spin-orbit exciton-induced phonon chirality in a quantum magnet. Proc Natl Acad Sci U S A 2024; 121:e2304360121. [PMID: 38457517 PMCID: PMC10945760 DOI: 10.1073/pnas.2304360121] [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: 03/16/2023] [Accepted: 11/17/2023] [Indexed: 03/10/2024] Open
Abstract
The interplay of charge, spin, lattice, and orbital degrees of freedom in correlated materials often leads to rich and exotic properties. Recent studies have brought new perspectives to bosonic collective excitations in correlated materials. For example, inelastic neutron scattering experiments revealed non-trivial band topology for magnons and spin-orbit excitons (SOEs) in a quantum magnet CoTiO3 (CTO). Here, we report phonon properties resulting from a combination of strong spin-orbit coupling, large crystal field splitting, and trigonal distortion in CTO. Specifically, the interaction between SOEs and phonons endows chirality to two [Formula: see text] phonon modes and leads to large phonon magnetic moments observed in magneto-Raman spectra. The remarkably strong magneto-phononic effect originates from the hybridization of SOEs and phonons due to their close energy proximity. While chiral phonons have been associated with electronic topology in some materials, our work suggests opportunities may arise by exploring chiral phonons coupled to topological bosons.
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Affiliation(s)
- David Lujan
- Department of Physics, Center of Complex Quantum Systems, The University of Texas at Austin, Austin, TX78712
- Center for Dynamics and Control of Materials, The University of Texas at Austin, Austin, TX78712
| | - Jeongheon Choe
- Department of Physics, Center of Complex Quantum Systems, The University of Texas at Austin, Austin, TX78712
- Center for Dynamics and Control of Materials, The University of Texas at Austin, Austin, TX78712
| | - Swati Chaudhary
- Department of Physics, Center of Complex Quantum Systems, The University of Texas at Austin, Austin, TX78712
- Department of Physics, Northeastern University, Boston, MA02115
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Gaihua Ye
- Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, TX79409
| | - Cynthia Nnokwe
- Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, TX79409
| | - Martin Rodriguez-Vega
- Department of Physics, Center of Complex Quantum Systems, The University of Texas at Austin, Austin, TX78712
- Department of Physics, Northeastern University, Boston, MA02115
| | - Jiaming He
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX78712
| | - Frank Y. Gao
- Department of Physics, Center of Complex Quantum Systems, The University of Texas at Austin, Austin, TX78712
- Center for Dynamics and Control of Materials, The University of Texas at Austin, Austin, TX78712
| | - T. Nathan Nunley
- Department of Physics, Center of Complex Quantum Systems, The University of Texas at Austin, Austin, TX78712
- Center for Dynamics and Control of Materials, The University of Texas at Austin, Austin, TX78712
| | - Edoardo Baldini
- Department of Physics, Center of Complex Quantum Systems, The University of Texas at Austin, Austin, TX78712
- Center for Dynamics and Control of Materials, The University of Texas at Austin, Austin, TX78712
| | - Jianshi Zhou
- Center for Dynamics and Control of Materials, The University of Texas at Austin, Austin, TX78712
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX78712
| | - Gregory A. Fiete
- Department of Physics, Northeastern University, Boston, MA02115
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Rui He
- Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, TX79409
| | - Xiaoqin Li
- Department of Physics, Center of Complex Quantum Systems, The University of Texas at Austin, Austin, TX78712
- Center for Dynamics and Control of Materials, The University of Texas at Austin, Austin, TX78712
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4
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Caprini L, Löwen H, Geilhufe RM. Ultrafast entropy production in pump-probe experiments. Nat Commun 2024; 15:94. [PMID: 38169471 PMCID: PMC10761836 DOI: 10.1038/s41467-023-44277-w] [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: 02/16/2023] [Accepted: 12/06/2023] [Indexed: 01/05/2024] Open
Abstract
The ultrafast control of materials has opened the possibility to investigate non-equilibrium states of matter with striking properties, such as transient superconductivity and ferroelectricity, ultrafast magnetization and demagnetization, as well as Floquet engineering. The characterization of the ultrafast thermodynamic properties within the material is key for their control and design. Here, we develop the ultrafast stochastic thermodynamics for laser-excited phonons. We calculate the entropy production and heat absorbed from experimental data for single phonon modes of driven materials from time-resolved X-ray scattering experiments where the crystal is excited by a laser pulse. The spectral entropy production is calculated for SrTiO3 and KTaO3 for different temperatures and reveals a striking relation with the power spectrum of the displacement-displacement correlation function by inducing a broad peak beside the eigenmode-resonance.
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Affiliation(s)
- Lorenzo Caprini
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany.
| | - Hartmut Löwen
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany
| | - R Matthias Geilhufe
- Department of Physics, Chalmers University of Technology, 412 96, Göteborg, Sweden.
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