Faculty of Mathematics and Physics, Charles University in Prague, V Holešovičkách 2, CZ-180 00 Prague 8, Czech Republic.
J Phys Condens Matter. 2012 Feb 8;24(5):055501. doi: 10.1088/0953-8984/24/5/055501. Epub 2012 Jan 6.
The spin reorientation temperature T(SR) of stoichiometric Fe(3)O(4), as well as of magnetite with a small number of vacancies and magnetite containing a low concentration of Ti, Zn, Al and Ga was measured on single-crystal samples using the ac susceptibility. In the same experiment the temperature T(V) of the Verwey transition was also found. The results show that a correlation between T(SR) and T(V) exists. The electronic structure of the compounds studied was determined using the density-functional-based GGA + U method. For stoichiometric magnetite the first and second cubic anisotropy constants were calculated, while for magnetite with defects the distribution of electron density using the 'atoms in molecules' approach was determined. Based on a combination of experimental results with the electronic structure calculations an explanation of the temperature dependence of the magnetocrystalline anisotropy of magnetite is suggested.
采用交流磁化率法测量了化学计量的 Fe(3)O(4)、具有少量空位的磁铁矿以及含有低浓度 Ti、Zn、Al 和 Ga 的磁铁矿的自旋再取向温度 T(SR)。在同一实验中还发现了 Verwey 转变的温度 T(V)。结果表明 T(SR)与 T(V)之间存在相关性。使用基于密度泛函的 GGA + U 方法确定了所研究化合物的电子结构。对于化学计量的磁铁矿，计算了第一和第二立方各向异性常数，而对于具有缺陷的磁铁矿，则使用“分子中的原子”方法确定了电子密度的分布。基于实验结果与电子结构计算的结合，提出了一种解释磁铁矿磁晶各向异性温度依赖性的方法。
