Rashba自旋轨道耦合对电子自旋磁化率的影响

The Effect of Rashba Spin-Orbital Coupling on Electronic Spin Susceptibility

研究了哈伯德强关联系统中,Rashba自旋轨道耦合(R-SOC)对二维正方晶格的自旋磁化率的影响.在线性响应理论中,自旋磁化率可以表示为推迟格林函数.对它所遵守的运动方程做哈特利-福克近似(HFA)和无规位相近似(RPA),再通过数值求解可得自旋磁化率.结果表明:没有R-SOC的静态磁化率Reχ(q,ω=0)随着库伦排斥势U的增大而增大,随温度T的增大而减小,库伦排斥势和温度对动态磁化率Reχ(q,ω=0)也有相似的影响.在加入R-SOC后,自旋轨道耦合的自旋磁化率实部在q=0附近形成了平底,而且平底宽度随VSO的增加而增大.同时自旋磁化率的虚部在平底边沿上呈现剧烈起伏.该效应可作为材料的自旋轨道耦合的显著标志.

The effect of the Rashba spin-orbital coupling on the spin susceptibility of an electronic system strongly correlated with a two-dimensional square lattice is studied.According to the linear response theory,spin susceptibility can be expressed with a retarded Green function.The equations of the spin susceptibility can be numerically solved with a random phase approximation and a Hartree-Fock approximation.The numerical results show that in the absence of spin-orbital coupling the static spin susceptibility Reχ(q;ω=0)increases with the increase of the Coulomb interaction U and decreases with increasing temperature.The Coulomb interaction U and temperature T have similar effects on the dynamic susceptibility Reχ(q;ω=0).When the spin orbital coupling is added into the system,the real part of the spin susceptibilityχ(q)shows a flat base around the q=0.The size of the flat base increases significantly with increasing VSO while the imaginary part ofχ(q)shows a drastic fluctuation at the boundary of the flat base.Thus,this effect becomes a clear signature of the spin-orbital coupling of a system.