First-principles KKR–CPA calculation of the magnetic and transport properties of La1−xXxMnO3 (X = Ca, Sr)
First-principles KKR–CPA calculation of the magnetic and transport properties of La1−xXxMnO3 (X = Ca, Sr)
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DOI：
10.1088/0953-8984/24/45/455501
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发表时间：
2012-11
期刊：
影响因子：
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通讯作者：
M. Ogura;Hisazumi Akai
中科院分区：
文献类型：
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作者：
M. Ogura;Hisazumi Akai
采用线性响应理论结合第一性原理计算的方法，研究了具有巨磁阻效应的（La1−xXx）MnO3 （X = Ca, Sr）的电输运性质。通过将相干势近似和Kubo-Greenwood公式应用于KKR Green函数方法来进行计算。为了揭示CMR效应的机制，计算了系统在A（层状）-、C（条纹）-和G（111）型反铁磁态以及局部矩无序态下的直流电导率作为x的函数。结果发现，系统的电导率强烈依赖于磁性结构，并且在A-和C型反铁磁结构下具有高度的各向异性。此外，还得出结论，当系统经历磁转变时，电导率会发生剧烈变化，这可能与观察到的CMR效应密切相关。本文指出，对于与磁转变相关的电导率发生如此剧烈的变化，Mn局部电子结构的半金属性质必须是必不可少的。
Electrical transport properties of (La1−xXx)MnO3 (X = Ca, Sr), which exhibits the so-called colossal magnetoresistance (CMR) effect, are investigated in the framework of linear response theory combined with first-principles calculation. The calculation is performed by applying the coherent potential approximation and Kubo–Greenwood formula to the KKR Green’s function method. In order to reveal the mechanism that underlies the CMR effects, the dc conductivities of the system in A (layered)-, C (stripe)-, and G (111)-type antiferromagnetic states as well as the local moment disordered state are calculated as a function of x. It is found that the conductivity of the system strongly depends on the magnetic structure and is highly anisotropic in the cases of A- and C-type antiferromagnetic structures. Also, it is concluded that a drastic change in the conductivity is expected when the system undergoes a magnetic transition, and that this might be closely related to the observed CMR effect. It is pointed out that, for such a drastic change in the conductivity to occur associated with the magnetic transition, the half-metallic nature of the Mn local electronic structure must be essential.