Theoretical Study on Spin and Orbital Moments in Actinide Magnets

在扩展的Hubbard模型的基础上，我们将5f轨道和自旋矩（分别为M_<orb>和M_<spin>）的hartee - fock （HF）计算扩展到除US外的nacl型铁磁体USe和UTe，其中包括U原子的5f、6d和7s轨道以及S原子的3s、3p轨道，并考虑了原子内多极5f-5f相互作用。在无自旋轨道相互作用的顺磁状态下，利用LDA-FLAPW计算确定了传递积分的参数。除F^0外，表示5f-5f相互作用的Slater积分由HF计算或高能光谱分析确定。我们确定了F^0，以便在总5f力矩的计算和实验之间取得一致。得到的M_<spin>和M_<orb>相互反平行，且M_<orb>/M_<2spin>之比为- 2.1，与实验结果一致。我们自洽地确定了5f态的14个数算子和91个（= _<14>C_2）非对角算子的期望值。发现后者的包含对于估计自旋偶极子的大小是重要的。我们还计算了第2型反铁磁体CoO和FeO的M_<spin>和M_<orb>的HF，考虑了全三维轨道、多极相互作用和o2p轨道。两个系统的M_<orb>均为- 1mu_B，这在单离子模型中已被指出。对于CoO，我们发现HF溶液除了具有共线结构外，还具有非共线磁性结构，这两种结构都被认为是中子衍射的候选结构。

We have extended the Hartree-Fock (HF) calculation of the 5f orbital and spin moments (M_<orb> and M_<spin>, respectively) to NaCl-type ferromagnet USe and UTe in addition to US on the basis of an extended Hubbard model, where the 5f, 6d and 7s orbits of U atom and the 3s, 3p ones of S atom are included and the intraatomic multipole 5f-5f interaction is taken into account. We determined the parameters of transfer integral by using the LDA-FLAPW calculation in the paramagnetic state without spin-orbit interaction. The Slater integral except F^0 representing the 5f-5f interaction is determined by HF calculation or analyzes of high-energy spectroscopies. We determine F^0 so as to obtain an agreement between the calculation and the experiment for the total 5f moment. The obtained M_<spin> and M_<orb > are antiparallel with each other and the ratio M_<orb>/M_<2spin> is - 2.1, which is in agreement with experimental results. We determine self-consistently the expectation values of 14 number operators and 91 (= _<14>C_2) off-diagonal operators of the 5f state. The includion of the latter is found to be important to estimate the magnitude of spin dipole.We have also performed the HF calculation of M_<spin> and M_<orb> of the second-type antiferromagnets CoO and FeO with taking into account the full 3d orbits and multipole interaction and the O 2p orbits. The calculated M_<orb> of both systems is found to be - 1mu_B, which has been pointed out in a single-ion model. For CoO,we found as a HF solution a non-collinear magnetic structure in addition to a collinear structure, both of which are suggested as candidates by the neutron diffraction.