Quantum spin liquid states are disordered magnetic states with strong magnetic correlations which can be described in terms of a large scale quantum entanglement.  While the realization of such phases has been proposed in several theoretical models, the experimental evidences of the existence of quantum spin liquids remains weak. The Kitaev model is an exactly solvable model which harbors a quantum spin liquid as ground state. In the past few years there was an intensive work on real material approaching the Kitaev model such as the Van, der Waals magnet α-RuCl₃. In this talk, I will introduce quantum spin liquids, the Kitaev model and the compound α-RuCl₃. Then I will summarize few years of intensive research in the magnetism community on the proximity between α-RuCl₃ and the Kitaev model. I will mainly describe the tentative to tune α-RuCl₃ towards the Kitaev spin liquid state or further away from the Kitaev limit using magnetic fields, hydrostatic pressure [1, 2] or chemical substitution [3, 4, 5].

References:
[1] G. Bastien, G. Garbarino, R. Yadav, F. J. Martinez-Casado, R. Beltrán Rodríguez, Q. Stahl, M. Kusch, S. P. Limandri, R. Ray, P. Lampen-Kelley, D. G. Mandrus, S. E. Nagler, M. Roslova, A. Isaeva, T. Doert, L. Hozoi, A. U. B. Wolter, B. Büchner, J. Geck, and J. van den Brink, “Pressure-induced dimerization and valence bond crystal formation in the Kitaev-Heisenberg magnet a-RuCl₃.” Phys. Rev. B 97, 241108(R) (2018).

[2] B. Wolf, D. A. S. Kaib, A. Razpopov, S. Biswas, K. Riedl, S. M. Winter, R. Valentí, Y. Saito, S. Hartmann, E. Vinokurova, T. Doert, A. Isaeva, G. Bastien, A. U. B. Wolter, B. Büchner and M. Lang, “Combined experimental and theoretical study of hydrostatic (He-gas) pressure effects in α-RuCl_3”, Phys. Rev. B 106, 134432 (2022).

[3] M. Roslova, J. Hunger, G. Bastien, D. Pohl, H. M. Haghighi, A. U. B. Wolter, A. Isaeva, U. Schwarz, B. Rellinghaus, K. Nielsch, B. Büchner, and T. Doert, “Detuning the Honeycomb of the α RuCl₃ Kitaev Lattice: A Case of Cr³⁺Dopant”. Inorganic Chemistry 58, 6659−6668 (2019).

[4] G. Bastien, M. Roslova, M. H. Haghighi, K. Mehlawat, J. Hunger, A. Isaeva, T. Doert, M. Vojta, B. Büchner and A. U. B. Wolter, “Spin-glass state and reversed magnetic anisotropy induced by Cr doping in the Kitaev magnet α-RuCl₃”. Phys. Rev. B 99, 214410 (2019).

[5] G. Bastien, E. Vinokurova, M. Lange, K. K. Bestha, L. T. Corredor, G. Kreutzer, A. Lubk, Th. Doert, B. Buchner, A. Isaeva and A. U. B. Wolter, “Dilution of the magnetic lattice in the Kitaev candidate α-RuCl₃ by Rh³⁺ doping”, Phys. Rev. Materials 6, 114403 (2022).