论文标题
超导ruo $ _2 $电影中的应变调节各向异性电子结构
Strain-modulated anisotropic electronic structure in superconducting RuO$_2$ films
论文作者
论文摘要
二进制勾画二酸RUO $ _2 $，由于其流动的抗铁磁性和应变引起的超导性，一直引起人们的兴趣。但是，应变机制及其对导致正常和超导状态的显微电子状态的影响仍然未公开。在这里，我们使用依赖偏振的氧气K-边缘X射线吸收光谱（XAS）研究了高度构造的外延（110）RUO $ _2 $胶片。通过检测源于O的前边缘峰：$ 2p $ - ru：$ 4D $杂交，我们发现了外延菌株对费米水平附近轨道/电子结构的影响。我们的数据显示，应变诱导的轨道水平的变化以及杂交强度的降低。此外，我们揭示了沿$ [110]/[1 \ bar {1} 0] $方向的明显平面内各向异性，该方向自然而然地源于底物的对称性上马菌株。 $ b_ {2g} $外上线强制性应变的对称成分打破了sublattice脱落性，从而导致费米级别的状态密度增加（$ e_f $），可能为超导性铺平了道路。这些结果强调了（110）ruo $ _2 $胶片中有效减少到骨晶格对称性的有效降低的重要性及其与超导和磁性特性的相关性。
The binary ruthenate, RuO$_2$, has been the subject of intense interest due to its itinerant antiferromagnetism and strain-induced superconductivity. The strain mechanism and its effect on the microscopic electronic states leading to the normal and superconducting state, however, remain undisclosed. Here, we investigate highly-strained epitaxial (110) RuO$_2$ films using polarization-dependent oxygen K-edge X-ray absorption spectroscopy (XAS). Through the detection of pre-edge peaks, arising from O:$2p$ - Ru:$4d$ hybridization, we uncover the effects of epitaxial strain on the orbital/electronic structure near the Fermi level. Our data show robust strain-induced shifts of orbital levels and a reduction of hybridization strength. Furthermore, we reveal a pronounced in-plane anisotropy of the electronic structure along the $[110]/[1\bar{1}0]$ directions naturally stemming from the symmetry-breaking epitaxial strain of the substrate. The $B_{2g}$ symmetry component of the epitaxially-enforced strain breaks a sublattice degeneracy, resulting in an increase of the density of states at the Fermi level ($E_F$), possibly paving the way to superconductivity. These results underscore the importance of the effective reduction from tetragonal to orthorhombic lattice symmetry in (110) RuO$_2$ films and its relevance towards the superconducting and magnetic properties.
