This title appears in the Scientific Report :
2017
Please use the identifier:
http://hdl.handle.net/2128/15868 in citations.
Please use the identifier: http://dx.doi.org/10.1103/PhysRevB.96.184301 in citations.
Transverse acoustic phonon anomalies at intermediate wave vectors in MgV 2 O 4
Transverse acoustic phonon anomalies at intermediate wave vectors in MgV 2 O 4
Magnetic spinels (with chemical formula AX2O4, with X a 3d transition metal ion) that also have an orbital degeneracy are Jahn-Teller active and hence possess a coupling between spin and lattice degrees of freedom. At high temperatures, MgV2O4 is a cubic spinel based on V3+ ions with a spin S=1 and...
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Personal Name(s): | Weber, T. (Corresponding author) |
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Roessli, B. / Stock, C. / Keller, T. / Schmalzl, K. / Bourdarot, F. / Georgii, R. / Ewings, R. A. / Perry, R. S. / Böni, P. | |
Contributing Institute: |
Streumethoden; JCNS-2 JCNS-ILL; JCNS-ILL JARA-FIT; JARA-FIT Streumethoden; PGI-4 |
Published in: | Physical Review B Physical review / B, 96 96 (2017 2017) 18 18, S. 184301 184301 |
Imprint: |
Woodbury, NY
Inst.
2017
|
DOI: |
10.1103/PhysRevB.96.184301 |
Document Type: |
Journal Article |
Research Program: |
Jülich Centre for Neutron Research (JCNS) Materials and Processes for Energy and Transport Technologies Quantum Condensed Matter: Magnetism, Superconductivity Controlling Collective States Controlling Collective States |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
Please use the identifier: http://dx.doi.org/10.1103/PhysRevB.96.184301 in citations.
Magnetic spinels (with chemical formula AX2O4, with X a 3d transition metal ion) that also have an orbital degeneracy are Jahn-Teller active and hence possess a coupling between spin and lattice degrees of freedom. At high temperatures, MgV2O4 is a cubic spinel based on V3+ ions with a spin S=1 and a triply degenerate orbital ground state. A structural transition occurs at TOO=63 K to an orbitally ordered phase with a tetragonal unit cell followed by an antiferromagnetic transition of TN=42 K on cooling. We apply neutron spectroscopy in single crystals of MgV2O4 to show an anomaly for intermediate wave vectors at TOO associated with the acoustic phonon sensitive to the shear elastic modulus (C11−C12)/2. On warming, the shear mode softens for momentum transfers near close to half the Brillouin zone boundary, but recovers near the zone center. High resolution spin-echo measurements further illustrate a temporal broadening with increased temperature over this intermediate range of wave vectors, indicative of a reduction in phonon lifetime. A subtle shift in phonon frequencies over the same range of momentum transfers is observed with magnetic fields. We discuss this acoustic anomaly in context of coupling to orbital and charge fluctuations. |