Magnetic field tunability of spin-polarized excitations in a high-temperature magnet

We bring together magnetic circular dichroism, photoconductivity, and complementary first-principles calculations in order to unravel spin-charge interactions in the high Curie temperature magnet ${\mathrm{NiFe}}_{2}{\mathrm{O}}_{4}$. Analysis uncovers a massive set of well-isolated spin-down states, a metamagnetic transition involving spin on the Ni center that switches the electronic structure of this system, and photoconductivity that depends on the magnetic field. These findings open the door for the creation and control of spin-polarized excitations from minority channel charge transfer in spinel ferrites.