Abstract
Magnetic Weyl semimetals with spontaneously broken time-reversal symmetry exhibit a large intrinsic anomalous Hall effect originating from the Berry curvature. To employ this large Hall current for room temperature topo-spintronics applications, it is necessary to fabricate these materials as thin or ultrathin films. Here, we experimentally demonstrate that Weyl semimetal Co2MnGa thin films (20–50 nm) show a large anomalous Hall angle ~11.4% at low temperature and ~9.7% at room temperature, which can be ascribed to the non-trivial topology of the band structure with large intrinsic Berry curvature. However, the anomalous Hall angle decreases significantly with thicknesses below 20 nm, which band structure calculations confirm is due to the reduction of the majority spin contribution to the Berry curvature. Our results suggest that Co2MnGa is an excellent material to realize room temperature topo-spintronics applications; however, the significant thickness dependence of the Berry curvature has important implications for thin-film device design.
Highlights
In Weyl semimetals (WSMs), a type of topological semimetal, the valence and conduction bands touch each other at isolated points called Weyl nodes, which can be understood as the monopoles and anti-monopoles of Berry curvature in momentum space[1]
Fermi arcs that connect the paired Weyl nodes. Due to this nontrivial topology of band structure, WSMs display a rich variety of exotic transport properties[2,3], like negative magnetoresistance, and giant magnitudes of anomalous Hall effect (AHE), planar Hall effect, and anomalous Nernst effect (ANE)
Magnetic WSMs have spontaneously broken timereversal symmetry, resulting in large intrinsic AHE originating from the Berry curvature[4,5,6]
Summary
In Weyl semimetals (WSMs), a type of topological semimetal, the valence and conduction bands touch each other at isolated points called Weyl nodes, which can be understood as the monopoles and anti-monopoles of Berry curvature in momentum space[1]. Fermi arcs that connect the paired Weyl nodes. Due to this nontrivial topology of band structure, WSMs display a rich variety of exotic transport properties[2,3], like negative magnetoresistance, and giant magnitudes of anomalous Hall effect (AHE), planar Hall effect, and anomalous Nernst effect (ANE). Magnetic WSMs have spontaneously broken timereversal symmetry, resulting in large intrinsic AHE originating from the Berry curvature[4,5,6]. Co-based Heusler compounds, face-centered cubic metallic compounds with space-group symmetry
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