Anomalous Hall effect in conical helimagnetic crystals
Anomalous Hall effect in conical helimagnetic crystals
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DOI：
10.1103/physrevb.107.035202
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发表时间：
2023-01
影响因子：
3.7
通讯作者：
Andrei Zadorozhnyi;Y. Dahnovsky
中科院分区：
文献类型：
--
作者：
Andrei Zadorozhnyi;Y. Dahnovsky
自旋螺旋织构可以显著改变HelImagnet中的电荷输运性质。我们发现反常霍尔效应(AHE)在锥形磁性结构中表现出与化学势有关的戏剧性行为。直接电导表现出奇异性，反常霍尔电流表现出极小值和极大值的变号现象。在最一般的情况下，我们解析地推导出能带和本征态的表达式。由于圆锥势，能带被分成两个非抛物线带，在这两个非抛物线带中，较低的带可以在方向上具有一个或两个极小值形状(ẑ是螺旋轴的方向)。我们证明了反常霍尔效应的起源不是拓扑的，而是由于能带在两个方向上的不对称性和相空间中由于锥形势而产生的自旋限制的相互作用。我们还研究了输运性质与锥体半角的关系，发现这种影响在螺旋态下最为明显。电流是用玻尔兹曼方程计算的，其中弛豫是由电声声子相互作用引起的。跃迁概率是一个非零非对角元素的矩阵，表明了强带间跃迁。能带间跃迁的起源是因为传导电子自旋与局域磁矩相互作用的锥形势的性质。为了验证所提出的理论，我们计算了晶体的电阻率与温度的关系，并发现了锥形相和顺磁相之间的相变不连续性。计算结果与实验数据吻合较好。此外，我们还预测了反常霍尔电阻率在相变时的不连续行为，在此相变时，(A)如果传导电子的相对论效应很小，则变为零，或(B)如果考虑Rashba/Dresselhaus效应，则变为非零值。
Spin-spiral texture can substantially change charge transport properties in helimagnets. We find the anomalous Hall effect (AHE) exhibiting the dramatic behavior with respect to chemical potentialin conical magnetic structures. The direct conductivity demonstrates kinks, and the anomalous Hall current exhibits minima and maxima changing the sign. We analytically derive the expression for energy bands and eigenstates in the most general case. Because of the conical potential, the energy bands are split into two nonparabolic bands where the lower band can have one- or two-minima shapes in thedirection (ẑ is a direction of the spiral axis). We prove that the origin of the anomalous Hall effect is not topological and is due to the interplay between the asymmetry of energy bands in theanddirections and spin restrictions in the phase space due to the conical potential. We also investigate the dependence of transport properties on cone half- angle, and find that the effects are most pronounced at(a helical state). Electric current is calculated using the Boltzmann equation where the relaxation is caused by electron-acoustic phonon interaction. The transition probability is found to be amatrix with nonvanishing off-diagonal elements indicating the strong interband transitions. The origin of interband transitions is because of the nature of the conical potential where conduction electron spins interact with localized magnetic moments. To verify the proposed theory, we calculate the temperature dependence of resistivity forcrystals and find the discontinuity at the phase transition between conical and paramagnetic phases. The calculations are in the excellent agreement with the experimental data. In addition, we predict the discontinuity behavior for the anomalous Hall resistivity at the phase transition where the resistivity exhibits the abrupt change at, (a) to zero if the relativistic effects for the conduction electrons are small or (b) to a nonzero value if Rashba/Dresselhaus effects are taken into account.