Site-Specific Pressure-Driven Spin-Crossover in Lu1-xScxFeO3.

Pressure-driven spin-crossover (PSCO) is a collective quantum phenomenon frequently observed in transition-metal-based systems. According to the crystal-field theory, PSCO highly depends on the surrounding coordination environment of a given magnetic ion; nevertheless, it has never been verified experimentally up to now. Herein, we report the observation of a site-specific PSCO phenomenon in Lu1-xScxFeO3, in which octahedrally coordinated Fe3+ in orthorhombic LuFeO3 and trigonal-bipyramidally coordinated Fe3+ in hexagonal Lu0.5Sc0.5FeO3 show distinct PSCO response to external pressure. X-ray emission spectra and DFT calculations reveal the key role of coordination environment in a PSCO process and predict the occurrence of PSCO for trigonal-bipyramidally coordinated Fe3+ above 100 GPa, far beyond that of 50 GPa for octahedrally coordinated Fe3+ in LuFeO3. The demonstration of site-specific PSCO sheds light on the state-of-the-art design of PSCO materials for directional applications.