Magnetoimpurity theory of resistivity and magnetoresistance for degenerate ferromagnetic semiconductors of the LaMnO3 type
Magnetoimpurity theory of resistivity and magnetoresistance for degenerate ferromagnetic semiconductors of the LaMnO3 type
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DOI：
10.1103/physrevb.54.16608
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发表时间：
1996-12-15
影响因子：
3.7
通讯作者：
Nagaev, EL
中科院分区：
文献类型：
--
作者：
Nagaev, EL
建立了LaMnO3型简并铁磁半导体的电阻率和磁阻理论。离居里点 T-C 不远的电阻率峰值在完美晶体中是不存在的，当电离杂质的电势是通常的静电电势和由接近杂质和远离杂质的局部磁化强度差异引起的交换电势之和时，可以通过磁化相关的杂质散射来解释电阻率峰值。这种交换电势在 T-C 附近达到最大值，这会导致迁移率降低和带尾板中的状态数量增加：即离域电荷载流子数量减少。后者可能非常重要，以至于它不仅表现在电阻率峰值上，而且表现在从高导状态到绝缘状态的转变中。磁场抑制交换电势，因此导致巨磁阻。
A theory for resistivity and magnetoresistance of LaMnO3-type degenerate ferromagnetic semiconductors is developed. The peak of resistivity not far from the Curie point T-C, which is absent in perfect crystals, is explained by a magnetization-dependent impurity scattering when the potential of ionized impurity is the sum of the usual electrostatic potential and an exchange potential caused by a difference in the local magnetizations close to the impurity and far from it. This exchange potential is a maximum in the vicinity of T-C, which causes a decrease in the mobility and an increase in the number of states in the band-tail slates: that is, decrease in the number of delocalized charge carriers. The latter may be so considerable that it may manifest itself not only in the resistivity peak but also in the transition from the high-conducting state to the insulating state. A magnetic field suppresses the exchange potential and for this reason causes a giant magnetoresistance.