Anomalous Hall effect in topological Weyl and nodal-line semimetal Heusler compound Co₂VAl

Abstract

Abstract Magnetic topological semimetals (TSMs) with broken time-reversal symmetry are very rare and have drawn significant attention in condensed matter physics due to their numerous intriguing topological properties. Among these various magnetic TSMs, Co 2 -based full Heusler compounds are of current interest, since a few of these materials exhibit Weyl and nodal fermions in their topological band structure. In this work, we report a comprehensive study of anomalous Hall effect (AHE) in the ferromagnetic full Heusler compound Co 2 VAl. Recent studies indicate that the intrinsic AHE is closely related to the Berry curvature of the occupied electronic Bloch states. The present study of Co 2 VAl attempts to understand and explore the possibility of topology-induced AHE. The anomalous Hall resistivity <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mi>ρ</mml:mi> <mml:mrow> <mml:mi>x</mml:mi> <mml:mi>y</mml:mi> </mml:mrow> <mml:mi>A</mml:mi> </mml:msubsup> </mml:math> is observed to scale quadratically with the longitudinal resistivity ρ xx . Our experimental results also reveal that the anomalous Hall conductivity (AHC) is ∼85 cm −1 at 2 K with an intrinsic contribution of ∼75.6 S cm −1 , and is nearly insensitive to temperature. The first principle calculations note that the Berry curvature originated from a gapped nodal line and symmetry-protected Weyl nodes near the Fermi level ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>E</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">F</mml:mi> </mml:mrow> </mml:msub> </mml:math> ) is the main source of AHE in this compound. Thus, this investigation on Co 2 VAl discloses that it is a ferromagnetic Weyl and nodal-line TSM. The theoretically calculated AHC is in well agreement with the experimentally obtained AHC.

Topics & Concepts