Concurrent Pressure-Induced Spin-State Transitions and Jahn-Teller Distortions in MnTe

Cooperative Jahn-Teller (JT) distortion accompanied by electromagnetic lattice coupling plays a crucial role in numerous important phenomena in materials science. The JT distortion occurring in high-spin 3d4 and 3d9 configurations in octahedral complexes is common, but similarly, large distortion due to lifting the degeneracy of t2g orbitals has so far seldomly been observed. Here, we report the discovery of the pressure-induced cooperative JT effect coupled with a large volume collapse of ∼12.8% and a magnetic moment collapse from S = 5/2 to S = 1/2 at ∼20.9 GPa in MnTe. The first-principles calculation indicates that weakened p-d hybridization and enhanced d state localization result in lifting t2g orbital degeneracy in Mn2+ (d5), which induced a cooperative JT effect-triggered electromagnetic lattice coupling. These findings suggest a new mechanism for the cooperative JT distortion via pressure-induced ligand distortion in antiferromagnetic materials.