Ferromagnetism in epitaxially strained CaxSr1-xIrO3 thin films

Epitaxial SrIrO3 and CaIrO3 thin films on STO(001) substrates crystallize in the perovskite structure and both display paramagnetic and semimetallic behavior. We successfully synthesized epitaxially strained thin films of the substitution series CaxSr1-xIrO3. A non-monotonic evolution of the out-of-plane lattice parameter is found, which for low x increases with respect to that for pure SrIrO3. Interestingly, this strained state for x>0.1 is accompanied by the occurrence of an anomalous Hall effect contribution below 50 K, which suggests the emergence of ferromagnetism. However, the ferromagnetic signal could not yet be confirmed by bulk magnetization measurements probably due to the small magnetic moment of the Iridium atoms. We propose XMCD measurements to investigate the Ir ferromagnetism and characterize the strain-induced phase in CaxSr1-xIrO3 for few selected concentrations x.

生长于STO(001)衬底上的外延SrIrO3与CaIrO3薄膜均采用钙钛矿结构结晶，二者均表现出顺磁性与半金属性特征。我们成功制备了取代固溶体系列CaxSr1-xIrO3的外延应变薄膜。研究发现该体系的面外晶格参数呈现非单调演化规律：当x较低时，其面外晶格参数相较于纯相SrIrO3有所增大。有趣的是，当x>0.1时，该应变态伴随50K以下反常霍尔效应分量的出现，这提示铁磁性的萌生。然而，受限于铱原子较小的磁矩，体磁化强度测量尚未能确认该铁磁性信号。我们建议开展X射线磁圆二色谱（X-ray Magnetic Circular Dichroism, XMCD）测量，以针对选定的少数x组分浓度，探究Sr1-xCaxIrO3中的铱基铁磁性并表征其应变诱导物相。