论文标题
通过椭圆测量学研究的Ti掺杂CA2RUO4中的自旋轨道耦合和晶体场分裂
Spin-orbit coupling and crystal-field splitting in Ti-doped Ca2RuO4 studied by ellipsometry
论文作者
论文摘要
在CA2RUO4中，旋转轨道耦合$ζ$和四方晶体场分裂$δ__{CF} $的竞争已有很多年在有争议上进行了争议。轨道职业取决于$δ_{CF}/ζ$，这使我们能够通过最低现场互面莫特 - 超音速激发的光谱量来解决该比率。我们研究了Ca $ _2 $ ru $ _ {0.99} $ ti $ _ {0.01} $ o $ $ _4 $在0.75-5 eV的元素测量范围内使用椭圆测量的范围内，使用可以种植的小型Ti浓度的大单晶。基于局部多重计算，我们的分析导致$ 2.4 \leqΔ_{Cf}/ζ\ leq 4 $在15 K处。主要的晶体场产生接近XY轨道顺序的基态，但自旋轨道耦合对于对特性的定量描述至关重要。此外，我们观察到，根据八人体畸变的减少，随着温度的升高，明显减少了$δ_{cf} $。
In Ca2RuO4, the competition of spin-orbit coupling $ζ$ and tetragonal crystal field splitting $Δ_{CF}$ has been discussed controversially for many years. The orbital occupation depends on $Δ_{CF}/ζ$, which allows us to address this ratio via the optical spectral weights of the lowest intersite Mott-Hubbard excitations. We study the optical conductivity of Ca$_2$Ru$_{0.99}$Ti$_{0.01}$O$_4$ in the range of 0.75 - 5 eV by ellipsometry, using the large single crystals that can be grown for small Ti concentrations. Based on a local multiplet calculation, our analysis results in $2.4 \leq Δ_{CF}/ζ\leq 4$ at 15 K. The dominant crystal field yields a ground state close to xy orbital order but spin-orbit coupling is essential for a quantitative description of the properties. Furthermore, we observe a pronounced decrease of $Δ_{CF}$ with increasing temperature, as expected based on the reduction of octahedral distortions.
