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Perovskite oxides AB O 3 continue to be a major focus in materials science. Of particular interest is the interplay between A and B cations as exemplified by intersite charge transfer (ICT), which causes novel phenomena including negative thermal expansion and metal-insulator transition. However, the ICT properties were achieved and optimized by cationic substitution or ordering. Here we demonstrate an anionic approach to induce ICT using an oxyhydride perovskite, EuVO 2 H, which has alternating layers of EuH and VO 2 . A bulk EuVO 2 H behaves as a ferromagnetic insulator with a relatively high transition temperature ( T C ) of 10 K. However, the application of external pressure to the Eu II V III O 2 H bulk or compressive strain from the substrate in the thin films induces ICT from the Eu II H layer to the V III O 2 layer due to the extended empty V d xy orbital. The ICT phenomenon causes the VO 2 layer to become conductive, leading to an increase in T C that is dependent on the number of carriers in the d xy orbitals (up to a factor of 4 for 10 nm thin films). In addition, a large perpendicular magnetic anisotropy appears with the ICT for the films of <100 nm, which is unprecedented in materials with orbital-free Eu 2+ , opening new perspectives for applications. The present results provide opportunities for the acquisition of novel functions by alternating transition metal/rare earth layers with heteroanions.

NiFe₂O₄ and ZnFe₂O₄ nanoparticles have been prepared encased in the MCM (Mobile Composition of Matter) type matrix. Their magnetic behavior has been studied and compared with that corresponding to particles of the same composition and of a similar size (prepared and embedded in amorphous silica or as bare particles). This study has allowed elucidation of the role exerted by the matrix and interparticle interactions in the magnetic behavior of each ferrite system. Thus, very different superparamagnetic behavior has been found in ferrite particles of similar size depending on the surrounding media. Also, the obtained results clearly provide evidence of the vastly different magnetic behavior for each ferrite system., Competing Interests: The authors declare no conflict of interest.