Spin-orbital correlations from complex orbital order in MgV2O4
Journal Article
·
· Physical Review Research
- University of Edinburgh (United Kingdom); STFC Rutherford Appleton Laboratory, Oxon (United Kingdom); Georgia Institute of Technology, Atlanta, GA (United States)
- University of California, Santa Barbara, CA (United States)
- University of Edinburgh (United Kingdom)
- Univ. Lille (France)
- STFC Rutherford Appleton Laboratory, Oxon (United Kingdom); University College London (United Kingdom)
- Institute Laue-Langevin (France)
- Paul Scherrer Institut (PSI), Villigen (Switzerland)
- Forschungszentrum Jülich GmbH, Garching (Germany)
- STFC Rutherford Appleton Laboratory, Oxon (United Kingdom)
- Technische Universität München (TUM), Garching (Germany)
MgV2O4 is a spinel based on magnetic V3+ ions, which host both spin (𝑆 = 1) and orbital (𝑙eff = 1) moments. Owing to the underlying pyrochlore coordination of the magnetic sites, the spins in MgV2O4 only antiferromagnetically order once the frustrating interactions imposed by the 𝐹𝑑$$\overline{3}$$𝑚 lattice are broken through an orbitally-driven structural distortion at T𝑆 ≃ 60 K. Consequently, a Néel transition occurs at T𝑁 ≃ 40 K. Low-temperature spatial ordering of the electronic orbitals is fundamental to both the structural and magnetic properties; however, considerable discussion on whether it can be described by complex or real orbital ordering is ambiguous. We apply neutron spectroscopy to resolve the nature of the orbital ground state and characterize hysteretic spin-orbital correlations using x-ray and neutron diffraction. Neutron spectroscopy finds multiple excitation bands and we parametrize these in terms of a multilevel (or excitonic) theory based on the orbitally degenerate ground state. Meaningful for the orbital ground state, we report an “optical-like” mode at high energies that we attribute to a crystal-field-like excitation from the spin-orbital 𝑗eff = 2 ground-state manifold to an excited 𝑗eff =1 energy level. We parametrize the magnetic excitations in terms of a Hamiltonian with spin-orbit coupling and local crystalline electric field distortions resulting from deviations from perfect octahedra surrounding the V3+ ions. We suggest that this provides compelling evidence for complex orbital order in MgV2O4. We then apply the consequences of this model to understand hysteretic effects in the magnetic diffuse scattering where we propose that MgV2O4 displays a high-temperature orbital memory of the low-temperature spin order.
- Research Organization:
- University of California, Santa Barbara, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
- Grant/Contract Number:
- SC0017752
- OSTI ID:
- 2205560
- Alternate ID(s):
- OSTI ID: 3015220
- Journal Information:
- Physical Review Research, Journal Name: Physical Review Research Journal Issue: 4 Vol. 5; ISSN 2643-1564
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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