论文标题
各向异性围绕系统中的磁性硬方向排序
Magnetic hard-direction ordering in anisotropic Kondo systems
论文作者
论文摘要
我们提出了一种通用机制，该机制解释了为什么许多近野材料沿着晶体场各向异性不支持的方向显示磁性排序。使用具有单离子各向异性的单个杂质围绕模型的重新归一化组（RG）分析，我们证明，在昆多温度上方的强烈波动驱动力驱动力在广泛的参数上重新定向，例如对于不同的旋转值$ s $和近野频道的数量$ n $。在四方系统中，对于易于平面或易于轴各向异性，这可能会发生。磁敏感性的特征交叉不是弱耦合RG处理的伪像，而是可以在蛮力扰动理论中复制。我们使用数值重新归一化组（NRG），我们表明，在屏幕上不足的时刻（$ s = 1 $，$ n = 1 $）具有易于平面各向异性，磁敏感性也可能发生在强耦合方案中（在Kondo温度下方）。这表明，这种屏幕不足的力矩的集体磁有序将沿着磁性硬轴发展。
We present a generic mechanism that explains why many Kondo materials show magnetic ordering along directions that are not favoured by the crystal-field anisotropy. Using a renormalization-group (RG) analysis of single impurity Kondo models with single-ion anisotropy, we demonstrate that strong fluctuations above the Kondo temperature drive a moment re-orientation over a wide range of parameters, e.g. for different spin values $S$ and number of Kondo channels $N$. In tetragonal systems this can happen for both easy-plane or easy axis anisotropy. The characteristic crossing of magnetic susceptibilities is not an artefact of the weak-coupling RG treatment but can be reproduced in brute-force perturbation theory. Employing numerical renormalization group (NRG), we show that for an under-screened moment ($S=1$, $N=1$) with easy-plane anisotropy, a crossing of magnetic susceptibilities can also occur in the strong-coupling regime (below the Kondo temperature). This suggests that collective magnetic ordering of such under-screened moments would develop along the magnetic hard axis.
