Large topological Hall effect in an easy-cone ferromagnet (Cr0.9B0.1)Te

Abstract

The Berry phase understanding of electronic properties has attracted special interest in condensed matter physics, leading to phenomena such as the anomalous Hall effect and the topological Hall effect. A non-vanishing Berry phase, induced in momentum space by the band structure or in real space by a non-coplanar spin structure, is the origin of both effects. Here, we report a sign conversion of the anomalous Hall effect and a large topological Hall effect in (Cr0.9B0.1)Te single crystals. The spin reorientation from an easy-axis structure at high temperature to an easy-cone structure below 140 K leads to conversion of the Berry curvature, which influences both, anomalous and topological, Hall effects in the presence of an applied magnetic field and current. We compare and summarize the topological Hall effect in four categories with different mechanisms and have a discussion into the possible artificial fake effect of topological Hall effect in polycrystalline samples, which provides a deep understanding of the relation between spin structure and Hall properties.In condensed matter physics, Berry phases have enabled a wider understanding of many physical concepts and phenomena, such as chiral anomalies [1,2] , magnetic monopoles [3] , and the anomalous Nernst effect [4] . Among them, the intrinsic anomalous Hall effect (AHE) requires the absence of time reversal symmetry and the orbital degeneracy to be lifted. The former is usually seen in ferromagnetic systems but also can be found in specific antiferromagnetic systems. The latter is due to relativistic effects such as the spin-orbit interaction, but can also be induced by a non-collinear magnetic spin texture [5,6] . The combination of these phenomena leads to momentumspace Berry curvature as a linear response to an applied electric field [7,8] . However, a real-space Berry phase originating from non-coplanar spin texture or magnetic topological excitations like

Giant Topological Hall Effect in the Noncollinear Phase of Two-Dimensional Antiferromagnetic Topological Insulator MnBi4Te7

“…Comparison of maximum topological Hall resistivity obtained in the present work with previously reported values. ,,,− We have listed the experimental conditions of each material when they reach their maximum topological Hall resistivity.…”

“…Surprisingly, a giant topological Hall resistivity (ρ yx T ) of ∼ 7 μΩ-cm is observed at 2 K, which is significantly higher than any previously reported value (Figure ). ,,,− This makes the MnBi 4 Te 7 system a potential candidate for spintronic applications.…”

Giant topological Hall effect in centrosymmetric tetragonal Mn2−xZnxSb

“…As a specific scenario, the formation of skyrmion lattice with topological spin texture is known to cause large THE [14]. In addition, there is also a proposal of artificial THE caused by signals from multiple magnetic phases in inhomogeneous or polycrystalline samples [50,51], which can be excluded because no secondary phases have been probed in structural and magnetic property characterizations on our single crystalline samples. To clarify the mechanism of the large THE, we have performed the temperature dependent magnetization for the x = 0.85 sample under several perpendicularly applied fields (H//c), as shown in Fig.…”

Widely Tunable Berry curvature in the Magnetic Semimetal Cr1+dTe2

“…Prominent among magnetic TMDs is Cr1+δTe2 -a self-intercalated TMD with tunable valency (Cr 2+ (3d 4 ) to Cr 4+ (3d 2 )) -which therefore serves as a promising candidate for modulating electronic and magnetic properties over a wide range (Fig. 1a) [37,38,39,40,41,42,43,44,45,46,47,48,49,50,51]. Our recent efforts have enabled a unique recipe to realize epitaxial thin films of Cr1+δTe2 over wide range of doping, with tunable magnetic properties [52].…”