Dynamical magnetotropic susceptibility as a new probe of Kitaev materials and beyond
Abstract
The magnetotropic susceptibility, k(ω), probes ultra-low-frequency uniform (q=0) spin and charge fluctuations in a crystal mounted on an oscillating cantilever: its real part shifts the oscillation frequency, while its imaginary part characterises the induced damping. We derive k(ω) within linear response theory for a generic correlated-electron Hamiltonian, showing that its real part is sensitive to magnetic anisotropy and its imaginary part encodes the uniform dynamical spin susceptibility, even for spin-symmetric insulators, while in metals it reveals eddy-current damping conditions. Using auxiliary-field quantum Monte Carlo, we compute k(ω) for microscopic models of α-RuCl3, finding that the low-temperature k(ω=0)/T scaling with B/T is a signature of dominant Kitaev coupling, robust to optical phonons, while the dynamical response shows local-moment-like features. We highlight applications to Kondo destruction quantum criticality, relevant to strange metallicity and unconventional superconductivity.
Related
- Dynamical quantum phase transitions in a pseudo-Hermitian Hamiltonian: The imbalanced-pairing Kitaev model
- Schwinger boson perturbation theory for spin-S Kitaev-Heisenberg magnets: phase diagram and dynamical response near Kitaev spin liquids
- Beyond Kitaev exchange: Γ'-driven magnetism in Ag3LiRh2O6
- Temperature evolution of spin dynamics in extended Kitaev models within an Abrikosov fermion theory beyond mean field
- Coupled dynamical Boltzmann transport equations with long-range electron-phonon and electron-electron interactions in two-dimensional materials
BibTeX
@misc{inacio2026dynamical,
title = {{Dynamical magnetotropic susceptibility as a new probe of Kitaev materials and beyond}},
author = {João C. Inácio and J. Schwab and G. Rakhmanova and S. Safari and V. Zambra and H. Nasir and S. Khim and S. Paschen and K. A. Modic and Fakher F. Assaad and Toshihiro Sato},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2605.00568},
eprint = {2605.00568},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.00568},
}
RIS
TY - UNPB
TI - Dynamical magnetotropic susceptibility as a new probe of Kitaev materials and beyond
AU - João C. Inácio
AU - J. Schwab
AU - G. Rakhmanova
AU - S. Safari
AU - V. Zambra
AU - H. Nasir
AU - S. Khim
AU - S. Paschen
AU - K. A. Modic
AU - Fakher F. Assaad
AU - Toshihiro Sato
PY - 2026
DA - 2026/09/17
PB - arXiv
DO - 10.48550/arxiv.2605.00568
UR - https://arxiv.org/abs/2605.00568
AB - The magnetotropic susceptibility, k(ω), probes ultra-low-frequency uniform (q=0) spin and charge fluctuations in a crystal mounted on an oscillating cantilever: its real part shifts the oscillation frequency, while its imaginary part characterises the induced damping. We derive k(ω) within linear response theory for a generic correlated-electron Hamiltonian, showing that its real part is sensitive to magnetic anisotropy and its imaginary part encodes the uniform dynamical spin susceptibility, even for spin-symmetric insulators, while in metals it reveals eddy-current damping conditions. Using auxiliary-field quantum Monte Carlo, we compute k(ω) for microscopic models of α-RuCl_3, finding that the low-temperature k(ω=0)/T scaling with B/T is a signature of dominant Kitaev coupling, robust to optical phonons, while the dynamical response shows local-moment-like features. We highlight applications to Kondo destruction quantum criticality, relevant to strange metallicity and unconventional superconductivity.
ER -