Overheated Topological Hall Effect: How Possible Artifacts Emerge?

Abstract

Topological Hall effect (THE) originates from the real-space Berry phase that an electron gains when its spin follows the spatially varying non-trivial magnetization textures, such as skyrmions. Such topologically protected magnetization textures can provide great potential for information storage and processing, which spurs a new wave of THE research. Since directly imaging the skyrmions or detecting the magnetic diffraction of skyrmion lattice are more challenging than conducting Hall measurements, THE has been widely used to attest the presence of skyrmions. However, as the key feature of THE, the bump/dip in Hall signal is not a sufficient proof of THE [Phys. Rev. B, \textbf{98},180408(2018) and Phys. Rev. B. \textbf{98}, 214440(2018)]. Here, we use empirical numerical modeling to demonstrate all possible THE-like signals that two anomalous Hall effect (AHE) signals with opposite signs can superpose. We accentuate that similar Hall signals observed in experiments require scrupulous re-examination to claim the advent of THE and related skyrmions. In addition, the origin of two-channel AHE in several representative examples are also been analyzed