Frustration of harmonic and solitonic helimagnetism on the body-centered tetragonal lattice of GdAlSi

TL;DR

This paper explores how GdAlSi, a tetragonal magnetic Weyl semimetal, exhibits frustration between harmonic and anharmonic helimagnetic states, revealing new physics in BCTL materials through experimental and theoretical analysis.

Contribution

It demonstrates that BCTL materials like GdAlSi can realize frustrated helimagnetic states similar to TLAFs, with experimental validation and mean-field calculations.

Findings

Resonant elastic X-ray scattering shows competition between harmonic and solitonic states.

GdAlSi exhibits frustration of helimagnetic states on a BCTL.

The work introduces a new paradigm for frustration physics in BCTL materials.

Abstract

The triangular lattice antiferromagnet (TLAF) with nearest-neighbor exchange interaction is a model platform in the field of frustrated magnetism. Here, anharmonic (`up-up-down') and harmonic (`120 degree') magnetic states compete, because the fundamental helimagnetic wave and its higher harmonic are degenerate in energy. We show that a body-centered tetragonal lattice (BCTL) can realize a similar frustration of harmonic and anharmonic helimagnetic states, and that the tetragonal magnetic Weyl semimetal GdAlSi realizes this scenario. In an applied magnetic field, resonant elastic X-ray scattering reveals a competition of harmonic cycloidal and solitonic double-Q states, well consistent with mean-field calculations. Our work provides a new paradigm for frustration physics in BCTL materials.