论文标题
室温铁磁性的微观起源
Microscopic Origin Of Room Temperature Ferromagnetism in a Double Perovskite Sr$_2$FeReO$_6$: a first principle and model Hamiltonian study
论文作者
论文摘要
尽管对非磁性b $'$ - 离子稀释了b-ions的磁性晶格，但对双钙晶（$ _2 $ bb $'$ o $ _6 $ _6 $ _6 $）中对室温的铁磁性的令人困惑的观察。 {\ it Ab-Initio}沿着相互空间中各种高对称方向的自旋螺旋电子结构计算用于确定进入扩展的海森伯格模型的交换相互作用，然后使用Monte Carlo Simulations经典地求解该模拟，以确定铁磁过渡温度T $ _C $ _C $。我们发现，必须考虑在非磁性站点（$ u $）上的现场库仑交互，以便获得接近实验值的T $ _C $。分析$ ab $ - $ $ INTIO $电子结构以及适当的模型Hamiltonian Trace Trace Trace t $ _C $增强的起源，并在这些站点引入的增强的交换拆分。反过来，这破坏了反铁磁交换频道，从而增强了T $ _C $。与SR $ _2 $ femoo $ _6 $相比，检查了非磁场上占用的作用。
The puzzling observation of room temperature ferromagnetism in double perovskites (A$_2$BB$'$O$_6$), despite having the magnetic lattice of B-ions diluted by non-magnetic B$'$-ions, have been examined for Sr$_2$FeReO$_6$. {\it Ab-initio} spin spiral electronic structure calculations along various high symmetry directions in reciprocal space are used to determine the exchange interactions entering an extended Heisenberg model, which is then solved classically using Monte Carlo simulations to determine the ferromagnetic transition temperature T$_c$. We find that one must consider onsite Coulomb interactions at the nonmagnetic Re sites ($U$) in order to obtain a T$_c$ close to the experimental value. Analysis of the $ab$-$initio$ electronic structure as well as an appropriate model Hamiltonian trace the origin of enhancement in T$_c$ with $U$ to the enhanced exchange splitting that is introduced at these sites. This in turn destabilizes the antiferromagnetic exchange channels, thereby enhancing the T$_c$. The role of occupancy at the non-magnetic sites is examined by contrasting with the case of Sr$_2$FeMoO$_6$.
