Spin-orbital exchange as a route to intertwined dipole-quadrupole orbital order in MnV2O4 under strong trigonal crystal field
Abstract
Orbitally degenerate systems provide a promising platform for realizing novel quantum phases driven by spin-orbital exchange interactions, as described by the Kugel-Khomskii model. Spinel vanadates, in which orbital degrees of freedom remain active, exhibit structural and magnetic transitions accompanied by orbital ordering, but the nature of the orbital state in MnV2O4 remains under debate. Here, we combine first-principles calculations with an effective spin-orbital model to address this problem. We show that a significant trigonal crystal field is present in high-temperature cubic phase and plays an essential role in determining the low-energy degrees of freedom. Based on the resulting parameters, we construct an effective Hamiltonian beyond the conventional dominant-hopping approximation and demonstrate that subdominant hopping processes strongly modify the spin-orbital exchange interactions. As a result, the system stabilizes a two-in/two-out magnetic configuration featuring spin canting and intertwined dipole-quadrupole orbital order.
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BibTeX
@misc{nakai2026spinorbital,
title = {{Spin-orbital exchange as a route to intertwined dipole-quadrupole orbital order in MnV$_2$O$_4$ under strong trigonal crystal field}},
author = {Hiroki Nakai and Yusuke Nomura},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2605.03028},
eprint = {2605.03028},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.03028},
}
RIS
TY - UNPB
TI - Spin-orbital exchange as a route to intertwined dipole-quadrupole orbital order in MnV_2O_4 under strong trigonal crystal field
AU - Hiroki Nakai
AU - Yusuke Nomura
PY - 2026
DA - 2026/10/09
PB - arXiv
DO - 10.48550/arxiv.2605.03028
UR - https://arxiv.org/abs/2605.03028
AB - Orbitally degenerate systems provide a promising platform for realizing novel quantum phases driven by spin-orbital exchange interactions, as described by the Kugel-Khomskii model. Spinel vanadates, in which orbital degrees of freedom remain active, exhibit structural and magnetic transitions accompanied by orbital ordering, but the nature of the orbital state in MnV_2O_4 remains under debate. Here, we combine first-principles calculations with an effective spin-orbital model to address this problem. We show that a significant trigonal crystal field is present in high-temperature cubic phase and plays an essential role in determining the low-energy degrees of freedom. Based on the resulting parameters, we construct an effective Hamiltonian beyond the conventional dominant-hopping approximation and demonstrate that subdominant hopping processes strongly modify the spin-orbital exchange interactions. As a result, the system stabilizes a two-in/two-out magnetic configuration featuring spin canting and intertwined dipole-quadrupole orbital order.
ER -