Growth and giant coercive field of spinel-structured Co3−xMnxO4 thin films

We grew epitaxial thin films of CoMn 2 O 4 and Co 2 MnO 4 on Nb-doped SrTiO 3 (011) and SrTiO 3 (001) single crystal substrates using pulsed laser deposition. The magnetic Curie temperature ( T c ) of the Co 2 MnO 4 thin films was ~176 K, which is higher than that of the bulk whereas CoMn 2 O 4 thin films exhibited a value of T c (~151 K) lower than that of the bulk. For the Co 2 MnO 4 thin films, the M − H loop showed a coercive field of ~0.7 T at 10 K, similar to the value for the bulk. However, the M −H loop of the CoMn 2 O 4 (0 ll ) thin film grown on a Nb-doped SrTiO 3 (011) substrate exhibited a coercive field of ~4.5 T at 30 K, which is significantly higher than those of the Co 2 MnO 4 thin film and bulk. This giant coercive field, only observed for the CoMn 2 O 4 (0 ll ) thin film, can be attributed to the shape anisotropy and strong spin-orbit coupling.