Pressure-induced dimerization and valence bond crystal formation in the Kitaev-Heisenberg magnet α-RuCl3

BASTIEN, G.; GARBARINO, G.; YADAV, R.; MARTINEZ-CASADO, F.J.; BELTRÁN RODRÍGUEZ, R.; STAHL, Q.; KUSCH, M.; LIMANDRI, S.P.; RAY, R.; LAMPEN-KELLEY, P.; MANDRUS, D.G.; NAGLER, S.E.; ROSLOVA, M.; ISAEVA, A.; DOERT, T.; HOZOI, L.; WOLTER, A.U.B.; BÜCHNER, B.; GECK, J.; VAN DEN BRINK, J.

Physical Review B

American Physical Society

Año: 2018 vol. 97

2469-9950

Magnetization and high-resolution x-ray diffraction measurements of the Kitaev-Heisenberg material α-RuCl3 reveal a pressure-induced crystallographic and magnetic phase transition at a hydrostatic pressure of p∼0.2 GPa. This structural transition into a triclinic phase is characterized by a very strong dimerization of the Ru-Ru bonds, accompanied by a collapse of the magnetic susceptibility. Ab initio quantum-chemistry calculations disclose a pressure-induced enhancement of the direct 4d-4d bonding on particular Ru-Ru links, causing a sharp increase of the antiferromagnetic exchange interactions. These combined experimental and computational data show that the Kitaev spin-liquid phase in α-RuCl3 strongly competes with the crystallization of spin singlets into a valence bond solid.