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arXiv 0801.0640cond-mat.str-elcond-mat.mes-hall
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d电子体系中AC反常霍尔电导理论

Theory of AC Anomalous Hall Conductivity in d-electron systems

Takuro Tanaka, Hiroshi Kontani

摘要:

为了阐明$d$-电子系统中反常霍尔效应的本质,我们在($d_{xz},d_{yz}$)-轨道紧束缚模型中研究了交流反常霍尔电导.我们得到了AC AHC的一般表达式$σ_{xy}(ω)$,它对有限准粒子阻尼率$γ$ = $\hbar/2τ$是有效的,并且发现AC AHC强烈依赖于$γ$.当$γ=+0$时,AC AHC在有限能量$Δ$处显示出尖峰,其源自带间粒子-空穴激发,其中$Δ$表示从费米能级测量的最小带分裂。与此相反,我们发现,这个尖峰迅速抑制时,$γ$是有限的。通过在$d$-电子系统中在$ω=Δ/2$处使用$γ(ω)$的实际值,显著抑制了尖峰。在本模型中,所得到的结果也代表了在顺磁状态下的AC自旋霍尔电导率。

英文摘要:

To elucidate the intrinsic nature of anomalous Hall effect (AHE) in $d$-electron systems, we study the AC anomalous Hall conductivity (AHC) in a tight-binding model with ($d_{xz},d_{yz}$)-orbitals. We drive a general expression for the AC AHC $σ_{xy}(ω)$, which is valid for finite quasiparticle damping rate $γ$=$\hbar/2τ$, and find that the AC AHC is strongly dependent on $γ$. When $γ=+0$, the AC AHC shows a spiky peak at finite energy $Δ$ that originates from the interband particle-hole excitation, where $Δ$ represents the minimum band-splitting measured from the Fermi level. In contrast, we find that this spiky peak is quickly suppressed when $γ$ is finite. By using a realistic value of $γ(ω)$ at $ω=Δ/2$ in $d$-electron systems, the spiky peak is considerably suppressed. In the present model, the obtained results also represents the AC spin Hall conductivity in a paramagnetic state.

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