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arXiv 1301.6355cond-mat.str-el
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自旋轨道耦合下的近藤效应

Kondo Effect in the Presence of Spin-Orbit Coupling

Takashi Yanagisawa

摘要:

自从CePt_3Si中发现超导电性以来,一系列非中心对称超导体一直是人们研究的热点。在非中心对称材料中,自旋-轨道耦合的存在使能带的简并度提高。这将带来新的影响,在近藤效应,因为带简并起着重要的作用,在电子散射的局域自旋。研究了自旋轨道耦合下的单杂质近藤问题。我们研究自旋轨道耦合对传导电子散射的影响,通过使用格林函数方法,s-d哈密顿量,采用去耦程序。结果,我们得到了一个封闭的格林函数方程组,由此我们可以计算物理量。近藤温度T_K由格林函数的奇异性估计。结果表明,T_K随自旋轨道耦合常数α的增大而减小。当2αk_F等于或大于k_BT_K(α=0)时,T_K由于带分裂而突然下降。这表明近藤崩塌伴随着T_K的急剧下降。电阻率的对数T依赖性将被自旋-轨道相互作用所掩盖。

英文摘要:

Recently, a series of noncentrosymmetric superconductors has been a subject of considerable interest since the discovery of superconductivity in CePt_3Si. In noncentrosymmetric materials, the degeneracy of bands is lifted in the presence of spin-orbit coupling. This will bring about new effects in the Kondo effect since the band degeneracy plays an important role in the scattering of electrons by localized spins. We investigate the single-impurity Kondo problem in the presence of spin-orbit coupling. We examine the effect of spin-orbit coupling on the scattering of conduction electrons, by using the Green's function method, for the s-d Hamiltonian, with employing a decoupling procedure. As a result, we obtain a closed system of equations of Green's functions, from which we can calculate physical quantities. The Kondo temperature T_K is estimated from a singularity of Green's functions. We show that T_K is reduced as the spin-orbit coupling constant αis increased. When 2αk_F is comparable to or greater than k_BT_K(α=0), T_K shows an abrupt decrease as a result of the band splitting. This suggests a Kondo collapse accompanied with a sharp decrease of T_K. The log T-dependence of the resistivity will be concealed by the spin-orbit interaction.

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