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Roy AP, Ss J, Dwij V, Khandelwal A, Chattopadhyay MK, Sathe V, Mittal R, Sastry PU, Achary SN, Tyagi AK, Babu PD, Le MD, Bansal D. Evidence of Strong Orbital-Selective Spin-Orbital-Phonon Coupling in CrVO_{4}. PHYSICAL REVIEW LETTERS 2024; 132:026701. [PMID: 38277598 DOI: 10.1103/physrevlett.132.026701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 12/05/2023] [Accepted: 12/14/2023] [Indexed: 01/28/2024]
Abstract
Coupling of orbital degree of freedom with a spin exchange, i.e., Kugel-Khomskii-type interaction (KK), governs a host of material properties, including colossal magnetoresistance, enhanced magnetoelectric response, and photoinduced high-temperature magnetism. In general, KK-type interactions lead to deviation in experimental observables of coupled Hamiltonian near or below the magnetic transition. Using diffraction and spectroscopy experiments, here we report anomalous changes in lattice parameters, electronic states, spin dynamics, and phonons at four times the Néel transition temperature (T_{N}) in CrVO_{4}. The temperature is significantly higher than other d-orbital compounds such as manganites and vanadates, where effects are limited to near or below T_{N}. The experimental observations are rationalized using first-principles and Green's function-based phonon and spin simulations that show unprecedentedly strong KK-type interactions via a superexchange process and an orbital-selective spin-phonon coupling coefficient at least double the magnitude previously reported for strongly coupled spin-phonon systems. Our results present an opportunity to explore the effect of KK-type interactions and spin-phonon coupling well above T_{N} and possibly bring various properties closer to application, for example, strong room-temperature magnetoelectric coupling.
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Affiliation(s)
- Aditya Prasad Roy
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra 400076, India
| | - Jayakrishnan Ss
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra 400076, India
| | - Vivek Dwij
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Mumbai, Maharashtra 400076, India
| | - Ashish Khandelwal
- Free Electron Laser Utilization Laboratory, Raja Ramanna Centre for Advanced Technology, Indore, Madhya Pradesh 452013, India
| | - M K Chattopadhyay
- Free Electron Laser Utilization Laboratory, Raja Ramanna Centre for Advanced Technology, Indore, Madhya Pradesh 452013, India
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Vasant Sathe
- UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore, Madhya Pradesh 452001, India
| | - Ranjan Mittal
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra 400085, India
| | - P U Sastry
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra 400085, India
| | - Srungarpu N Achary
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
- Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Avesh K Tyagi
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
- Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Peram D Babu
- UGC-DAE Consortium for Scientific Research, Mumbai Centre, R5-Shed, BARC, Trombay, Mumbai, Maharashtra 400085, India
| | - Manh Duc Le
- ISIS facility, Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX Oxfordshire, United Kingdom
| | - Dipanshu Bansal
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra 400076, India
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Kung HH, Maiti S, Wang X, Cheong SW, Maslov DL, Blumberg G. Chiral Spin Mode on the Surface of a Topological Insulator. PHYSICAL REVIEW LETTERS 2017; 119:136802. [PMID: 29341673 DOI: 10.1103/physrevlett.119.136802] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Indexed: 05/05/2023]
Abstract
Using polarization-resolved resonant Raman spectroscopy, we explore collective spin excitations of the chiral surface states in a three dimensional topological insulator, Bi_{2}Se_{3}. We observe a sharp peak at 150 meV in the pseudovector A_{2} symmetry channel of the Raman spectra. By comparing the data with calculations, we identify this peak as the transverse collective spin mode of surface Dirac fermions. This mode, unlike a Dirac plasmon or a surface plasmon in the charge sector of excitations, is analogous to a spin wave in a partially polarized Fermi liquid, with spin-orbit coupling playing the role of an effective magnetic field.
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Affiliation(s)
- H-H Kung
- Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - S Maiti
- Department of Physics, University of Florida, Gainesville, Florida 32611, USA
| | - X Wang
- Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
- Rutgers Center for Emergent Materials, Rutgers University, Piscataway, New Jersey 08854, USA
| | - S-W Cheong
- Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
- Rutgers Center for Emergent Materials, Rutgers University, Piscataway, New Jersey 08854, USA
| | - D L Maslov
- Department of Physics, University of Florida, Gainesville, Florida 32611, USA
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
| | - G Blumberg
- Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
- National Institute of Chemical Physics and Biophysics, 12618 Tallinn, Estonia
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Matsuura K, Sagayama H, Uehara A, Nii Y, Kajimoto R, Kamazawa K, Ikeuchi K, Ji S, Abe N, Arima TH. Spin-Orbital Correlated Dynamics in the Spinel-Type Vanadium Oxide MnV_{2}O_{4}. PHYSICAL REVIEW LETTERS 2017; 119:017201. [PMID: 28731738 DOI: 10.1103/physrevlett.119.017201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Indexed: 06/07/2023]
Abstract
We investigate the magnetic dynamics in the spinel-type vanadium oxide MnV_{2}O_{4}. Inelastic neutron scattering around 10 meV and a Heisenberg model analysis have revealed that V^{3+} spin-wave modes exist at a lower-energy region than previously reported. The scattering around 20 meV cannot be reproduced with the spin-wave analysis. We propose that this scattering could originate from the spin-orbital coupled excitation. This scattering is most likely attributable to V^{3+} spin-wave modes, entangled with the orbital hybridization between t_{2g} orbitals.
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Affiliation(s)
- Keisuke Matsuura
- Department of Advanced Materials Science, the University of Tokyo, Kashiwa 277-8561, Japan
| | - Hajime Sagayama
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan
| | - Amane Uehara
- Department of Applied Physics, the University of Tokyo, Tokyo 113-8656, Japan
| | - Yoichi Nii
- Department of Basic Science, the University of Tokyo, Komaba 153-8902, Japan
| | - Ryoichi Kajimoto
- J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Kazuya Kamazawa
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan
| | - Kazuhiko Ikeuchi
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan
| | - Sungdae Ji
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan
| | - Nobuyuki Abe
- Department of Advanced Materials Science, the University of Tokyo, Kashiwa 277-8561, Japan
| | - Taka-Hisa Arima
- Department of Advanced Materials Science, the University of Tokyo, Kashiwa 277-8561, Japan
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Laverock J, Chen B, Preston ARH, Newby D, Piper LFJ, Tung LD, Balakrishnan G, Glans PA, Guo JH, Smith KE. Low-energy V t2g orbital excitations in NdVO3. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:455603. [PMID: 25336521 DOI: 10.1088/0953-8984/26/45/455603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The electronic structure of NdVO(3) and YVO(3) has been investigated as a function of sample temperature using resonant inelastic soft x-ray scattering at the V L(3)-edge. Most of the observed spectral features are in good agreement with an atomic crystal-field multiplet model. However, a low energy feature is observed at ∼ 0.4 eV that cannot be explained by crystal-field arguments. The resonant behaviour of this feature establishes it as due to excitations of the V t(2g) states. Moreover, this feature exhibits a strong sample temperature dependence, reaching maximum intensity in the orbitally-ordered phase of NdVO(3), before becoming suppressed at low temperatures. This behaviour indicates that the origin of this feature is a collective orbital excitation, i.e. the bi-orbiton.
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Affiliation(s)
- J Laverock
- Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, MA 02215, USA
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Onishi T, Yamaguchi K. Theoretical calculations of effective exchange integrals by spin projected and unprojected broken-symmetry methods II: Cluster models of Jahn–Teller distorted K2CuF4 solid. Polyhedron 2009. [DOI: 10.1016/j.poly.2008.11.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Horsch P, Oleś AM, Feiner LF, Khaliullin G. Evolution of spin-orbital-lattice coupling in the RVO3 perovskites. PHYSICAL REVIEW LETTERS 2008; 100:167205. [PMID: 18518242 DOI: 10.1103/physrevlett.100.167205] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Revised: 02/12/2008] [Indexed: 05/26/2023]
Abstract
We introduce a microscopic model which unravels the physical mechanisms responsible for the observed phase diagram of the RVO3 perovskites. It reveals a nontrivial interplay between superexchange, the orbital-lattice coupling due to the GdFeO3-like rotations of the VO6 octahedra, and orthorhombic lattice distortions. We find that the lattice strain affects the onset of the magnetic and orbital order by partial suppression of orbital fluctuations. The present approach also provides a natural explanation of the observed reduction of magnon energies from LaVO3 to YVO3.
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Affiliation(s)
- Peter Horsch
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
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Miyasaka S, Yasue T, Fujioka J, Yamasaki Y, Okimoto Y, Kumai R, Arima T, Tokura Y. Magnetic field switching between the two orbital-ordered states in DyVO3. PHYSICAL REVIEW LETTERS 2007; 99:217201. [PMID: 18233244 DOI: 10.1103/physrevlett.99.217201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2007] [Indexed: 05/25/2023]
Abstract
The critical phase competition between different spin-orbital-ordered states has been investigated for the DyVO3 single crystal. As temperature is lowered, the compound exhibits a reentrant spin and orbital ordering (SO and OO) transition: C-->G-->C type for SO and G-->C-->G type for OO. It was found that a magnetic field also drives the phase transition from C to G for OO and concomitantly from G to C for SO, the latter of which is coupled with the metamagnetic transition of the Dy 4f moments. The mechanism of this novel magnetic-field-induced orbital switching is discussed.
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Affiliation(s)
- S Miyasaka
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
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Fujioka J, Miyasaka S, Tokura Y. Doping variation of orbitally induced anisotropy in the electronic structure of La1-xSrxVO3. PHYSICAL REVIEW LETTERS 2006; 97:196401. [PMID: 17155646 DOI: 10.1103/physrevlett.97.196401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Indexed: 05/12/2023]
Abstract
The variation of anisotropic charge dynamics in the course of a filling-control insulator-metal transition (IMT) in La(1-x)Sr(x)VO3 has been investigated by measurements of optical conductivity spectra with the focus on the role of the t(2g)-orbital degree of freedom. The orbitally induced anisotropic feature of the Mott-gap excitation as well as of the doping-induced midinfrared excitation is suppressed with increasing x, and instead the isotropic and incoherent dynamics of the doped hole dominates over the low-energy excitation near and above the IMT point.
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Affiliation(s)
- J Fujioka
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
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Ishihara S. Hole dynamics in spin and orbital ordered vanadium perovskites. PHYSICAL REVIEW LETTERS 2005; 94:156408. [PMID: 15904170 DOI: 10.1103/physrevlett.94.156408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2004] [Indexed: 05/02/2023]
Abstract
A theory of doped perovskite vanadates with spin and orbital orders is presented. Mobile holes are strongly renormalized by spin excitations (magnons) in the spin G-type and orbital C-type (SG-OC) order, and orbital excitations (orbitons) in the spin C-type and orbital G-type (SC-OG) one. Hole dynamics in a staggered t(2g) orbital array is distinguished from that in the antiferromagnetic order and the e(g) orbital one. The fragile character of the (SG-OC) order in Y1-xCaxVO3 is attributed to the orbiton softening induced by a reduction of the spin order parameter.
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Affiliation(s)
- Sumio Ishihara
- Department of Physics, Tohoku University, Sendai 980-8578, Japan
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