Fluctuation-driven magnetic hard-axis ordering in metallic ferromagnets.
Fluctuation-driven magnetic hard-axis ordering in metallic ferromagnets.
复制标题
金属铁磁体中波动驱动的磁性硬轴排序。
DOI：
10.1103/physrevlett.113.147001
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发表时间：
2014
影响因子：
8.6
通讯作者：
Krüger F
中科院分区：
文献类型：
--
作者：
Krüger F
我们证明了软电子粒子-空穴涨落和磁各向异性之间的相互作用可以驱动铁磁矩指向磁性硬轴。作为概念的证明，我们给出了具有局域库仑和洪德相互作用以及自旋轨道引起的易平面各向异性的一般两带模型的这一行为。相图是在费米子量子无序有序方法中计算的，该方法基于围绕具有未指定取向的磁性有序状态的自洽自由能展开。量子涨落使易平面铁磁体的一级跃迁低于一个三临界点。在更低的温度下，方向相关的横向涨落主导着磁各向异性，力矩反转到沿着磁硬轴方向。我们在最近的实验中讨论了我们的发现，这些实验显示了沿着磁性硬方向的这种不寻常的顺序。
We demonstrate that the interplay between soft electronic particle-hole fluctuations and magnetic anisotropies can drive ferromagnetic moments to point along a magnetic hard axis. As a proof of concept, we show this behavior explicitly for a generic two-band model with local Coulomb and Hund’s interactions and a spin-orbit-induced easy plane anisotropy. The phase diagram is calculated within the fermionic quantum order-by-disorder approach, which is based on a self-consistent free-energy expansion around a magnetically ordered state with unspecified orientation. Quantum fluctuations render the transition of the easy-plane ferromagnet first order below a tricritical point. At even lower temperatures, directionally dependent transverse fluctuations dominate the magnetic anisotropy, and the moments flip to lie along the magnetic hard axis. We discuss our findings in the context of recent experiments that show this unusual ordering along the magnetic hard direction.