High Pressure Magnetometry and Neutron Scattering of the Frustrated Spinel MgCr₂O₄

Magnesium Chromate (MgCr₂O₄) is an example of a cubic AB₂O₄ spinel in which the magnetic Cr³⁺ ion occupies a pyrochlore lattice that hosts highly frustrated antiferromagnetic spin interactions. Its proximity to two distinct highly degenerate phases, the coulomb and spin-spiral-liquid, results in unique behavior prior to the onset of magnetic ordering at around 12K. Compression of the material under high-pressure may permit the tuning of exchange interaction terms, possibly enabling one of these nearly degenerate states to dominate.



This talk reports high pressure magnetometry of phase pure polycrystalline MgCr₂O₄ conducted using an HMD pressure cell attachment for the MPMS3 SQUID-based magnetometer. The results indicate significant changes in the low-temperature response of the material’s magnetic susceptibility under applied pressures of up to approximately 1.5 GPa. Neutron spectroscopy measurements will be presented along with Landau-Lifshitz calculations to further elucidate the influence of pressure on the magnetic interactions giving rise to the complex phase diagram.