Large change in the exchange interactions of HgCr2O4 under very high magnetic fields (vol 83, 214401, 2011)

The combination of high-frequency electron magnetic resonance (EMR) and magnetization measurements enables us to evaluate the exchange interactions in high-field phases of polycrystalline samples of the chromium spinel oxide HgCr2O4. The evaluation indicates that the lattice distortion in this compound largely modulates the exchange interactions between the Cr3+ spins to stabilize its distinct plateau with one-half of the saturation magnetization. Furthermore, we show that a release of the lattice distortion occurs in very high magnetic fields. Our result suggests that the spin-lattice coupling, which causes the large changes in the exchange interactions, plays a crucial role in giving rise to the peculiar magnetization process of HgCr2O4.