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Séminaire MCBT : mardi 26 octobre à 11h

Gaël Bastien (Charles University, Prague)

Institut Néel, bat. E 3rd floor, room 424 E & visio (webcast @) : https://univ-grenoble-alpes-fr.zoom.us/my/matteo.dastuto

Important: limited place available on site, if you like to attend in person, please, send a mail to matteo.dastuto@neel.cnrs.fr


Title: “Effect of hydrostatic pressure or chemical substitution in the Kitaev magnet α-RuCl3


The Kitaev model attracts much attention, since it is an exactly solvable model with a topological quantum spin liquid (QSL) ground state and Majorana Fermions as magnetic excitations. In the Kitaev model spin 1/2 sit on a honeycomb lattice and undergo bound directional magnetic interactions called Kitaev interactions. The Kitaev magnet α-RuCl3 shows a strong proximity to the Kitaev model, despite the occurrence of an antiferromagnetic order below 7K instead of the QSL state. Its magnetic properties can be well explained by a magnetic Hamiltonian including Kitaev interactions, Heisenberg interactions and off-diagonal magnetic interactions. The aim of our project was to test whether this compound can be tuned closer to the Kitaev limit or towards a QSL state by the use hydrostatic pressure and chemical substitution. We report a pressure-induced structural transition into a non-magnetic state: a valence bond crystal with the formation of Ru-Ru bonds [1]. We also show, that the partial substitution of the Ru3+ ions by non-magnetic ions Rh3+ suppresses the magnetic order towards a quantum disordered state.

[1] G. Bastien, et al., Phys. Rev. B  97, 241108(R) (2018)