Unconventional anomalous Hall effect in hexagonal polar magnet Y_3Co_8Sn_4

TL;DR

This study reports the observation of an unconventional anomalous Hall effect in Y_3Co_8Sn_4, linked to topological Weyl points and magnetic textures, with implications for topological magnetism and spintronics.

Contribution

It reveals the presence of UAHE in Y_3Co_8Sn_4 both below and above T_C, supported by experimental and ab-initio calculations, highlighting the role of topological Weyl points and magnetic order.

Findings

UAHE observed both below and above T_C

Topological Weyl points contribute to UAHE

Large anomalous Hall conductivity detected

Abstract

We report a rare realization of unconventional anomalous Hall effect (UAHE) both below and above the magnetic transition temperature (T_C) in a hexagonal noncentrosymmetric magnet Y_3Co_8Sn_4, using a combined experimental and ab-initio calculations. Occurrence of such UAHE is mainly attributed to the reciprocal (KS) topology (i.e. the presence of topological Weyl points at/near the Fermi level), along with some contribution from the topological magnetic texture, as inferred from the measured field-dependent ac susceptibility. The effect of UAHE on the measured transport behavior however evolves differently with temperature above and below T_C, suggesting different physical mechanism responsible in the two phases. A unique planar ferrimagnetic ordering is found to be the most stable state with ab-plane as the easy plane below TC, as observed experimentally. The simulated net magnetization and the moment per Co atom agrees fairly well with the measured values. A reasonably large AHC is also observed in both the phases (above and below and T_C) of the present compound, which is again not so ubiquitous. Our results underscore the family of R_3Co_8Sn_4 (R= rare earth) polar magnets as a compelling backdrop for exploring the synergy of topological magnetism and non-trivial electronic bands, pivotal for spintronic applications.