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arXiv 2102.05489cond-mat.str-el
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自旋轨道耦合反铁磁体中热涨落对有效自旋轨道耦合的抑制

Suppression of effective spin-orbit coupling by thermal fluctuations in spin-orbit coupled antiferromagnets

Jan Lotze, Maria Daghofer

摘要:

我们将有限温度变分集团方法应用于$t_{2g}$子壳层中四个电子(即两个空穴)的强关联自旋轨道耦合模型。我们专注于反铁磁莫特绝缘体,特别是钙$_2$ RuO $_4$,并确定一个交叉的低温制度,自旋轨道耦合是必不可少的,高温制度,它留下几个签名。在单粒子光谱中可以看到交叉,其中$xz$和$yz$光谱在高温下几乎是一维的(如弱自旋-轨道耦合所预期的)。在较低的温度下,自旋轨道耦合混合了所有三个轨道,它们变得更加二维。然而,更强的影响被认为是在两个粒子的可观测量,如在具有明确的现场角动量的状态的重量。因此,我们确定了神秘的中温“轨道顺序相变”,这已在各种X射线衍射和吸收实验报告在$T\approx 260\;K$,作为自旋轨道相关性的发病的签名。

英文摘要:

We apply the finite-temperature variational cluster approach to a strongly correlated and spin-orbit coupled model for four electrons (i.e. two holes) in the $t_{2g}$ subshell. We focus on parameters suitable for antiferromagnetic Mott insulators, in particular Ca$_2$RuO$_4$, and identify a crossover from the low-temperature regime, where spin-orbit coupling is essential, to the high-temperature regime where it leaves few signatures. The crossover is seen in one-particle spectra, where $xz$ and $yz$ spectra are almost one dimensional (as expected for weak spin-orbit coupling) at high temperature. At lower temperature, where spin-orbit coupling mixes all three orbitals, they become more two dimensional. However, stronger effects are seen in two-particle observables like the weight in states with definite onsite angular momentum. We thus identify the enigmatic intermediate-temperature 'orbital-order phase transition', which has been reported in various X-ray diffraction and absorption experiments at $T\approx 260\;K$, as the signature of the onset of spin-orbital correlations.

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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