Predominant Electronic Order Parameter for Structural Chirality -- Role of Spinless Electronic Toroidal Multipoles

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Main Authors: Oiwa, Rikuto, Kusunose, Hiroaki
Format: Preprint
Published: 2025
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author Oiwa, Rikuto
Kusunose, Hiroaki
author_facet Oiwa, Rikuto
Kusunose, Hiroaki
contents We discuss predominant order parameters for structural chirality, and demonstrate that time-reversal-even axial-quadrupole plays a key role in stabilizing a chiral structure. Using the symmetry-adapted closest Wannier model of the trigonal Te and Se, we quantify the evolution of the spin-independent (spinless) and spin-dependent (spinful) electric toroidal (ET) (axial) multipole moments across the transition from an achiral to a chiral structure. Our results clearly identify that a spin-independent off-diagonal real hopping between $p$ orbitals, which corresponds to the bond-cluster spinless ET quadrupole of $(3z^{2}-r^{2})$ type $G_{u}$, is the predominant order parameter in stabilizing helical structures. We further elucidate that the above itinerant spinless ET quadrupole induces a monopole-like orbital angular momentum texture in the momentum space, which can be observed via circular-dichroism in soft x-ray photoemission spectroscopy measurement. Our findings highlight a critical role of the orbital angular momentum in chiral materials rather than less dominant spin angular momentum arising from the relativistic spin-orbit coupling.
format Preprint
id arxiv_https___arxiv_org_abs_2504_11682
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Predominant Electronic Order Parameter for Structural Chirality -- Role of Spinless Electronic Toroidal Multipoles
Oiwa, Rikuto
Kusunose, Hiroaki
Materials Science
We discuss predominant order parameters for structural chirality, and demonstrate that time-reversal-even axial-quadrupole plays a key role in stabilizing a chiral structure. Using the symmetry-adapted closest Wannier model of the trigonal Te and Se, we quantify the evolution of the spin-independent (spinless) and spin-dependent (spinful) electric toroidal (ET) (axial) multipole moments across the transition from an achiral to a chiral structure. Our results clearly identify that a spin-independent off-diagonal real hopping between $p$ orbitals, which corresponds to the bond-cluster spinless ET quadrupole of $(3z^{2}-r^{2})$ type $G_{u}$, is the predominant order parameter in stabilizing helical structures. We further elucidate that the above itinerant spinless ET quadrupole induces a monopole-like orbital angular momentum texture in the momentum space, which can be observed via circular-dichroism in soft x-ray photoemission spectroscopy measurement. Our findings highlight a critical role of the orbital angular momentum in chiral materials rather than less dominant spin angular momentum arising from the relativistic spin-orbit coupling.
title Predominant Electronic Order Parameter for Structural Chirality -- Role of Spinless Electronic Toroidal Multipoles
topic Materials Science
url https://arxiv.org/abs/2504.11682