Seebeck switch by helimagnetism in the Weyl semimetal GdAlSi

Switching the thermoelectric Seebeck effect by an external perturbation, such as pulse current, strain, or magnetic field may enable new functionality for advanced thermoelectric devices. Previously, a magnetization-dependent Seebeck effect has been reported in ferromagnets, where conduction electrons close to the Fermi energy are weakly coupled to the net magnetization through the relativistic spin-orbit coupling (SOC). However, this ferromagnetic anisotropic magneto-Seebeck effect (AMSE) is small and may suffer from sizable stray magnetic fields hindering device applications.

In this talk, we introduce a new principle to control the Seebeck effect by breaking a solid's rotational symmetry via periodic magnetic order. We reveal Seebeck switch by up to 65 % in a prototypical tetragonal helimagnet, the Weyl semimetal GdAlSi, characterized by low carrier density. Unlike the conventional ferromagnetic AMSE, the present helimagnetic AMSE arises from a reconfiguration of the electronic structure by many-body correlations and does not, in principle, require the relativistic spin-orbit coupling.