Light-driven octupolar inverse Faraday effect and multipolar order in Mott insulators

Fuente: arXiv
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Auteurs principaux: Banerjee, Saikat, Steinhöfel, Tara, Lange, Florian, Eschrig, Matthias, Fehske, Holger
Format: Preprint
Publié: 2026
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author Banerjee, Saikat
Steinhöfel, Tara
Lange, Florian
Eschrig, Matthias
Fehske, Holger
author_facet Banerjee, Saikat
Steinhöfel, Tara
Lange, Florian
Eschrig, Matthias
Fehske, Holger
contents Hidden multipolar orders in spin-orbit-coupled Mott insulators provide a promising setting for correlated quantum matter, yet their control and detection remain major challenges. Here, we demonstrate that circularly polarized light enables both in $4d^2/5d^2$ systems with edge-sharing octahedra. Using a Floquet Schrieffer-Wolff expansion of a driven Hubbard-Kanamori model, we derive a low-energy multipolar Hamiltonian with two qualitatively new light-driven terms. One is an effective static field that couples linearly to the magnetic octupole, realizing an octupolar inverse Faraday effect. The other is a bond-dependent anisotropic exchange interaction absent in equilibrium. These two couplings are the key result of this work: the first provides a direct optical handle on hidden octupolar order, while the second reorganizes the multipolar exchange landscape and opens an enlarged Kitaev-like multipolar liquid regime. Their interplay produces a nonequilibrium multipolar phase space inaccessible in equilibrium, enabling optical tuning among antiferro-octupolar, ferro-octupolar, partially polarized ferro-quadrupolar, Ising octupolar, and multipolar liquid phases. We further show that the induced multipolar order couples to the lattice, generating reversible trigonal and tetragonal distortions that provide structural fingerprints in pump-probe experiments. Our work establishes a general mechanism for the optical generation, control, and detection of hidden multipolar quantum states.
format Preprint
id arxiv_https___arxiv_org_abs_2605_08049
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Light-driven octupolar inverse Faraday effect and multipolar order in Mott insulators
Banerjee, Saikat
Steinhöfel, Tara
Lange, Florian
Eschrig, Matthias
Fehske, Holger
Strongly Correlated Electrons
Hidden multipolar orders in spin-orbit-coupled Mott insulators provide a promising setting for correlated quantum matter, yet their control and detection remain major challenges. Here, we demonstrate that circularly polarized light enables both in $4d^2/5d^2$ systems with edge-sharing octahedra. Using a Floquet Schrieffer-Wolff expansion of a driven Hubbard-Kanamori model, we derive a low-energy multipolar Hamiltonian with two qualitatively new light-driven terms. One is an effective static field that couples linearly to the magnetic octupole, realizing an octupolar inverse Faraday effect. The other is a bond-dependent anisotropic exchange interaction absent in equilibrium. These two couplings are the key result of this work: the first provides a direct optical handle on hidden octupolar order, while the second reorganizes the multipolar exchange landscape and opens an enlarged Kitaev-like multipolar liquid regime. Their interplay produces a nonequilibrium multipolar phase space inaccessible in equilibrium, enabling optical tuning among antiferro-octupolar, ferro-octupolar, partially polarized ferro-quadrupolar, Ising octupolar, and multipolar liquid phases. We further show that the induced multipolar order couples to the lattice, generating reversible trigonal and tetragonal distortions that provide structural fingerprints in pump-probe experiments. Our work establishes a general mechanism for the optical generation, control, and detection of hidden multipolar quantum states.
title Light-driven octupolar inverse Faraday effect and multipolar order in Mott insulators
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2605.08049