Magnetoresistance of compensated semimetals in confined geometries
Magnetoresistance of compensated semimetals in confined geometries
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DOI：
10.1103/physrevb.95.165410
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发表时间：
2017-04-10
影响因子：
3.7
通讯作者：
Titov, M.
中科院分区：
文献类型：
--
作者：
Alekseev, P. S.;Dmitriev, A. P.;Titov, M.
双组分导体——例如，半金属和窄带半导体——通常在很宽的温度范围内表现出异常强的磁阻。在这样的系统中，霍尔电压在电荷中性附近的抑制会在垂直于电流和磁场的方向上产生强烈的准粒子漂移。即使在弱磁场中，这种漂移也会造成电阻的几何增加。结合玻尔兹曼动力学方程和样品静电学，我们建立了二维和三维空间的微观磁输运理论。在受限几何中，补偿霍尔效应总是伴随着样品边缘附近和大尺度非均匀性下的电子-空穴复合。因此，在电荷补偿附近，经典边缘电流可能会主导电阻。这种效应导致在很宽的参数范围内二维线性磁阻。在三维空间中，磁电阻在磁场中通常是二次型的，线性区仅限于磁场垂直于样品表面的矩形样品。
Two-component conductors -e.g., semimetals and narrow-band semiconductors-often exhibit unusually strong magnetoresistance in a wide temperature range. Suppression of the Hall voltage near charge neutrality in such systems gives rise to a strong quasiparticle drift in the direction perpendicular to the electric current and magnetic field. This drift is responsible for a strong geometrical increase of resistance even in weak magnetic fields. Combining the Boltzmann kinetic equation with sample electrostatics, we develop a microscopic theory of magnetotransport in two and three spatial dimensions. The compensated Hall effect in confined geometry is always accompanied by electron-hole recombination near the sample edges and at large-scale inhomogeneities. As the result, classical edge currents may dominate the resistance in the vicinity of charge compensation. The effect leads to linear magnetoresistance in two dimensions in a broad range of parameters. In three dimensions, the magnetoresistance is normally quadratic in the field, with the linear regime restricted to rectangular samples with magnetic field directed perpendicular to the sample surface.