Origin of Anisotropy in Gadolinium Crystal Using a New Spin Hamiltonian
Origin of Anisotropy in Gadolinium Crystal Using a New Spin Hamiltonian
复制标题
使用新的自旋哈密顿量研究钆晶体各向异性的起源
DOI：
10.1088/0256-307x/37/5/057501
复制
发表时间：
2020
影响因子：
3.5
通讯作者：
Liu Chuan
中科院分区：
文献类型：
--
作者：
Wei Dan;Chen Zhibin;Yang Hui;Cao Yongjun;Liu Chuan
Single crystal rare-earth magnets, such as hexagonal-close-packed gadolinium, usually have a large second order anisotropy K2 and a negative first order anisotropy K1 at low temperatures, which are difficult to explain using microscopic theories. An atomic scale effective spin Hamiltonian ℱ[{Si}] is proposed, which, apart from the usual isotropic nearest neighbor coupling J, consists of two new terms that are different for in-plane and out-of-plane neighbors and which are characterized by two new couplings C1 and C2, respectively. The hybrid Monte–Carlo method is utilized to sample this system to the desired Boltzmann-like distribution exp(−ℱ/kBT). It is found that K2 and K1 are compatible with the experimental values and arise naturally from the exchange anisotropy C1 and C2, which are less than 0.01 in magnitude of the isotropic exchange energy J. This new model spin Hamiltonian can also be applied to study other magnetic properties.
