High-pressure ilmenite-type MnVO₃: crystal and spin structures in the itinerant-localized regimes

Herein we report the Peierls-like transition in the high-pressure ilmenite-type MnVO3. The first-order structural transition from a low-temperature P1 to a high-temperature R3 occurs at 475 K, accompanied by a semiconductor to metal-like transition. The triclinic distorted phase presents a V-V dimerization with a short similar to 2.85 angstrom bond formation at 300 K. Below 80 K MnVO3 orders antiferromagnetically with a small ferromagnetic component. Neutron diffraction reveals that both Mn and V cations contribute to the magnetic ordering, contrary to what expected on the V-V dimer formed. Extended Huckel and DFT calculations expose that the formation of covalent pairing is only partially achieved, contrary to the MgVO3 and CoVO3 counterparts.