Strain-induced antiferromagnetic transition in CaMnO3 Thin Films

Bulk CaMnO3 (CMO) is a canted G-type antiferromagnet. Theoretical calculations reveal a strain-induced transition to A-type antiferromagnetic ordering when grown in thin-film on SrTiO3 (STO) or LaAlO3 (LAO) substrates leading to a net uncompensated interfacial moment. HAADF-HRSTEM measurements reveal a sharp strained interfacial region, while magnetometry reveals a large average saturation magnetization which decreases with film thickness. Polarized neutron reflectometry will allow us to measure the depth-dependent saturation magnetization in thin CMO films to attribute the observed magnetism to strain at the film-substrate interface. We will compare samples grown on different substrates (STO vs. LAO) and of different thicknesses (3 nm vs. 30 nm) to verify the effects of strain and film relaxation.

块体钙锰氧化物（CaMnO₃，CMO）是一种倾斜G型反铁磁体。理论计算表明，当在钛酸锶（SrTiO₃，STO）或铝酸镧（LaAlO₃，LAO）衬底上生长薄膜时，应变会诱导其转变为A型反铁磁有序，从而产生净未补偿界面磁矩。高角度环形暗场高分辨扫描透射电子显微镜（HAADF-HRSTEM）测量显示存在清晰的应变界面区域，而磁测量则揭示了较大的平均饱和磁化强度，该强度随薄膜厚度增加而降低。极化中子反射法将使我们能够测量CMO薄膜中深度依赖的饱和磁化强度，从而将观测到的磁性归因于膜-衬底界面处的应变。我们将对比在不同衬底（STO与LAO）上生长且厚度不同（3 nm与30 nm）的样品，以验证应变和薄膜弛豫的影响。