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arXiv 0712.0210cond-mat.mes-hallcond-mat.str-el
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铁磁体中反常电、热电和热霍尔效应的量子输运理论

Quantum transport theory of anomalous electric, thermoelectric, and thermal Hall effects in ferromagnets

Shigeki Onoda, Naoyuki Sugimoto, Naoto Nagaosa

摘要:

反常霍尔输运现象的机制,如果它是内在或外在的起源,一直有争议。我们提出了一个统一的理论,它们的铁磁金属与稀杂质在零温度下,在量子输运理论与自洽的T矩阵近似。在费米能E_F和自旋轨道相互作用能E_{SO}一定的情况下(E_F > E_{SO}),发现了三种区域作为散射率\hbar /τ的函数。(i)在\hbar /τ< u_{imp} E_{SO} D的超净情况下,顶点修正的斜散射决定了反常霍尔电导率σ_{xy},其中u_{imp}为杂质势强度,D为态密度.随着\hbar /τ的增加,这种非本征斜散射贡献迅速衰减。(ii)在中等脏区(u_{imp} E_{SO} D < \hbar /τ< E_{SO}),σ_{xy}由内禀无耗散的Berry相贡献决定,当费米能级附近的带色散的偶然简并被自旋-轨道相互作用提升时,该贡献被共振增强到e^2/ \hbar的量级。(iii)进一步增加\hbar /τ,出现了σ_{xy} \propto σ_{xx}^{1.6}标度,这已被最近的实验所证实。文中还讨论了热霍尔电导率和热电霍尔电导率。

英文摘要:

The mechanism of the anomalous Hall transport phenomena, if it is of the intrinsic or extrinsic origin, has been controversial. We present a unified theory of them for ferromagnetic metals with dilute impurities at the zero temperature, in terms of a quantum transport theory with the self-consistent T-matrix approximation. With the Fermi energy E_F and the spin-orbit interaction energy E_{SO} being fixed (E_F > E_{SO}), three regimes are found as a function of the scattering rate \hbar/τ. (i) In the superclean case \hbar/τ< u_{imp} E_{SO}D, the skew scattering from the vertex correction dominates the anomalous Hall conductivity σ_{xy}, where u_{imp} is the impurity potential strength and D is the density of states. With increasing \hbar/τ, this extrinsic skew-scattering contribution rapidly decays. (ii) In the moderately dirty regime u_{imp}E_{SO}D < \hbar/τ< E_{SO}, σ_{xy} is dominated by the intrinsic dissipationless Berry-phase contribution, which is resonantly enhanced to the order of e^2/\hbar when an accidental degeneracy of band dispersions around the Fermi level is lifted by the spin-orbit interaction. (iii) Further increasing \hbar/τ, a σ_{xy}\proptoσ_{xx}^{1.6} scaling appears, which has been verified by recent experiments. The themal and thermoelectric Hall conductivities are also discussed.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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