Confinement of magnetism in atomically-thin $L{a}_{0.7}S{r}_{0.3}Cr{O}_3$/$L{a}_{0.7}S{r}_{0.3}Mn{O}_3$ heterostructures

At crystalline interfaces where a valence mismatch exists, electronic and structural interactions may occur to relieve the polar mismatch leading to the stabilization of non-bulklike phases. We show that spontaneous reconstructions at polar $L{a}_{0.7}S{r}_{0.3}Mn{O}_3$ interfaces are correlated with suppressed ferromagnetism for film thicknesses on the order of a unit cell. We investigate the structural and magnetic properties of valence-matched $L{a}_{0.7}S{r}_{0.3}Cr{O}_3$ - $L{a}_{0.7}S{r}_{0.3}Mn{O}_3$ interfaces using a combination of high-resolution electron microscopy, first principles theory, synchrotron X-ray scattering and magnetic spectroscopy and temperature-dependent magnetometry. A combination of an antiferromagnetic coupling between the $L{a}_{0.7}S{r}_{0.3}Cr{O}_3$ and $L{a}_{0.7}S{r}_{0.3}Mn{O}_3$ layers and a suppression of interfacial polar distortions are found to result in robust long range ferromagnetic ordering for ultra-thin $L{a}_{0.7}S{r}_{0.3}Mn{O}_3$. These results underscore the critical importance of interfacial structural and magnetic interactions in the design of devices based on two-dimensional oxide magnetic systems.