Designing Ru-based quantum spin liquid candidates: microscopic modelling and experimental signatures*

The spin-orbit assisted Mott insulator α-RuCl₃ has been one of the most discussed honeycomb Kitaev material candidates in recent years. While the material enters a so-called zigzag antiferromagnetic order at low temperatures, various experiments at finite temperature or finite magnetic field  have been interpreted as hallmarks of Kitaev physics, a subject which is presently under intensive debate, specially in view of the fact that the magnetic exchange interactions are extremely sensitive to lattice effects.

The latter can be exploited via pressure, strain or chemical pressure, as well as changes of lattice geometry, with the possibility of tuning the system towards regions where a quantum spin liquid phase may be realized. Following this strategy, and by using a combination of first-principles calculations and effective-model considerations, we present results [1-5] on the electronic and magnetic properties of the family of RuX₃ (X=Cl,Br,I), monolayer RuCl₃, heterostructures of RuCl₃/graphene as well as the triangular lattice-based NaRuO₂ and unveil a rather complex magnetism that we compare with available experiments.

This work has been done in collaboration with D. Kaib, E. I.I. Mazin, A. Razpopov, K. Riedl, S. Winter, J. Knolle, L. Balents, E. Henriksen, B. Yang, A. Tsen, S. Wilson