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arXiv 2103.09395cond-mat.mtrl-sci
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自旋相关能带结构演化引起的巨非线性反常霍尔效应

Giant nonlinear anomalous Hall effect induced by spin-dependent band structure evolution

Xiangyu Cao, Jie-Xiang Yu, Pengliang Leng, Changjiang Yi, Yunkun Yang, Shanshan Liu, Lingyao Kong, Zihan Li, Xiang Dong, Youguo Shi, Jiadong Zang, Faxian Xiu

摘要:

反常霍尔效应(AHE)是揭示磁性材料拓扑性质的关键输运特征。虽然AHE通常与磁化强度成比例,但非线性表明存在复杂的磁性和电子顺序。非线性AHE包括拓扑霍尔效应(THE),其已被广泛用于识别实空间中自旋手性的存在。但它原则上可以通过倒易空间中的Berry曲率由能带结构演化引起。由于现实空间和互惠空间中相互交织的机制,这种影响在很大程度上被忽视了。在这里,我们观察到一个巨大的非线性AHE的电阻率高达383.5 uohm cm,贡献前所未有的97%的总霍尔响应在EuCd2As2。此外,通过将磁场从[001]方向倾斜30°,可以进一步增强,达到高达21%的大反常霍尔角。虽然它表现出与THE完全相同的双峰特征,但标度分析和第一性原理计算表明,Berry相对自旋倾斜非常敏感,非线性AHE是磁场作用下能带结构演化的结果.当自旋从面内反铁磁基态逐渐向面外方向倾斜时,会发生带交叉和带反转,在倾斜角为45°的Γ点处引入带隙。这有助于增强Berry曲率,从而提高本征霍尔电导率。我们的结果明确地揭示了能带结构的敏感依赖于自旋倾斜过程在外部磁场下,其显着的影响输运性质,这也需要考虑在其他磁性材料。

英文摘要:

Anomalous Hall effect (AHE) is the key transport signature unlocking topological properties of magnetic materials. While AHE is usually proportional to the magnetization, the nonlinearity suggests the existence of complex magnetic and electron orders. Nonlinear AHE includes the topological Hall effect (THE) that has been widely used to identify the presence of spin chirality in real space. But it can in principle be induced by band structure evolution via Berry curvatures in the reciprocal space. This effect has been largely overlooked due to the intertwined mechanisms in both real and reciprocal spaces. Here, we observed a giant nonlinear AHE with the resistivity up to 383.5 uohm cm, contributing unprecedentedly 97% of the total Hall response in EuCd2As2. Moreover, it can be further enhanced by tilting the magnetic field 30° away from [001] direction, reaching a large anomalous Hall angle up to 21%. Although it shows exactly the same double-peak feature as THE, our scaling analysis and first-principles calculations reveal that the Berry phase is extremely sensitive to the spin canting, and nonlinear AHE is a consequence of band structure evolution under the external magnetic fields. When the spins gradually tilt from the in-plane antiferromagnetic ground state to out-of-plane direction, band crossing and band inversion occur, introducing a bandgap at Γ point at a canting angle of 45°. That contributes to the enhancement of Berry curvature and consequently a large intrinsic Hall conductivity. Our results unequivocally reveal the sensitive dependence of band structures on spin tilting process under external magnetic fields and its pronounced influence on the transport properties, which also need to be taken into consideration in other magnetic materials.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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