In orthorhombic perovskite oxides (RMO$_3$), substituting R$^{ 3+}$ rare-earth cations tailors the spin, orbital, and charge degrees of freedom of the central M$^{ 3+}$ transition metal cations through lattice distortions. In turn, these modify also the surrounding environment of R$^{ 3+}$. When both R$^{ 3+}$ and M$^{ 3+}$ exhibit magnetic properties, phenomena such as spin reorientation and magnetization reversal can occur. In fact, the underlying exchange interactions between M-$3d$ spins and R-$4f$ magnetic moments enrich the multifunctional character of RMO$_3$, particularly when combined with structural distortions. They play a crucial role in achieving appealing properties such as robust magnetoelectricity with non-collinear magnetic orders. Here, we explore the exchange coupling in epitaxial PrVO$_3$ thin films, selectively probing the magnetism of cation sublattices, and uncovering simultaneous V$^{ 3+}$ $3d$ spin reorientation and Pr$^{ 3+}$ $4f$ magnetization reversal using spectroscopy techniques. By strain engineering, we manipulate the lattice distortions to rationalize their role in coupling $3d$ spins and $4f$ magnetic moments. Theorectical calculations show that octahedral rotations and Jahn-Teller distortions act as tuning mechanisms, promoting competition between orbital and spin orders. The observed coupling between magnetic cations and lattice distortions can be extended to other orthorhombic RMO$_3$ systems, advancing the understanding of controlling spins in engineered perovskite heterostructures and superlattices.
Categories: cond-mat.mtrl-sci cond-mat.str-el