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

Abstract

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 3d 4 and 3d 9 configurations in octahedral complexes is common, but similarly, large distortion due to lifting the degeneracy of t 2g 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 t 2g orbital degeneracy in Mn 2+ (d 5 ), 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.

Pressure-Induced Reversible and Irreversible Multistate Switching in NiAs-Type Chromium Selenides

“…Further compression increases the distortion in the orthorhombic structure, resulting in the splitting of the strongest diffraction peak. Similar phenomena have been found in many NiAs-type compounds, that is, pressure-induced NiAs-to-MnP-type structural phase transition. − The number of atoms in a MnP-type unit cell is twice that of a NiAs-type one. For Cr 2 Se 3 , no obvious new peak and diffraction peak splitting is observed under HP, which is the same as the other derivative NiAs-type compounds, such as Cr 3 Te 4 and Cr 5 Te 8 .…”

“…The large-volume collapse caused by pressure-driven SCO has been reported in some manganese-based chalcogenides. With the magnetic moment collapse from S = 5/2 to S = 1/2, the pressure-induced giant-volume collapse of ∼22% occurs in MnS and MnSe while that of ∼12.8% in MnTe . However, in CrTe and corresponding derivative compounds such as Cr 3 Te 4 and Cr 5 Te 8 , no obvious volume collapse has been observed under HP .…”

“…NiAs-type compounds tend to undergo structural phase transitions to the MnP-type structure under HP, including MnAs, MnTe, CrTe, and CoSb . This atomic-shift-type (i.e., martensitic) phase transition always leads to abrupt changes in both the electrical and magnetic properties of materials.…”

Pressure-Induced Changes in the Crystal Structure and Electrical Conductivity of GeV4S8

“…To quantitatively evaluate the Jahn–Teller effect under compression, the Jahn–Teller distortion σ JT has been characterized by the following equation − σ JT = true{ prefix∑ i = 1 2 ( L V−S − true L − V−S ) true} 1 / 2 where L V–S represents the bond lengths between atoms V and S, such as L V(2)–S(3) and L V(2)–S(4) , while L̅ V–S is the average distance between V and S in the VS 6 octahedron under various pressures. As shown in Figure c, from ambient pressure up to ∼13 GPa, the JT distortion is relatively stable with a slight fluctuation, but starting from ∼13 GPa, the JT distortion continuously decreases with pressure up to ∼27 GPa, and then it changes nonlinearly.…”

Tailoring Spin State of Perovskite Oxides by Fluorine Atom Doping for Efficient Oxygen Electrocatalysis

“…Stability is another important factor in determining oxygen electrocatalytic performance. [ 51 ] Figures S6 and S7, Supporting Information, illustrate the LSV curves for the initial stability test and after 5000 cycles, with a high degree of overlap, indicating the stability of the material during the test. Besides, we re‐do a series of material structure, morphology and composition tests of F 0.2 ‐LCO after the OER test.…”