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.