Anisotropic suppression of the phononic thermal conductivity by magnetic field in SmAlSi

TL;DR

This study investigates how magnetic fields influence phonon heat transport in the magnetic Weyl semimetal SmAlSi, revealing anisotropic suppression of thermal conductivity depending on the field orientation, which could inform thermoelectric material design.

Contribution

It provides the first detailed analysis of anisotropic phononic thermal conductivity suppression by magnetic fields in SmAlSi, highlighting the role of magnetic structure orientation.

Findings

Phonon heat transport is unaffected by magnetic field when applied perpendicular to current.

Strong suppression of phonon thermal conductivity occurs when magnetic field is parallel to current.

The magnetic field's effect on thermal conductivity is highly anisotropic at low temperatures.

Abstract

We report the thermal and electrical conductivity data for the magnetic Weyl semimetal SmAlSi measured in a magnetic field (B) with two different orientations. In one case, B was applied perpendicular to the heat or charge current, in the other they were parallel. For both configurations, the magnetic field affects the magnetic structure identically as B is always parallel to the equivalent tetragonal axis. Our results indicate that phonon heat transport in response to the magnetic field exhibits strong anisotropy at low temperature: it appears to be independent of B in the perpendicular configuration but is strongly suppressed in the parallel configuration. Understanding this unusual behaviour can lead to designing better materials for thermoelectricity or directional heat switches.