Contrasting electronic states of RuI3 and RuCl3

The spin-orbital entangled states are of great interest as they hold exotic phases and intriguing properties. Here we use first-principles calculations to investigate the electronic and magnetic properties of RuI3 and RuCl3 in both bulk and monolayer cases. Our results show that RuI3 bulk is a paramagnetic metal, which is in agreement with recent experiments. We find that the Ru3+ ion of RuI3 is in the spin-orbital entangled jeff = 12 state. More interestingly, a metal-insulator transition occurs from RuI3 bulk to monolayer, and this is mainly due to the band narrowing with the decreasing lattice dimensionality and to the Ru-I hybridization altered by the I 5p spin-orbit coupling. In contrast, RuCl3 bulk and monolayer both show Mott-insulating behavior, the Ru3+ ion is in the formal S = 12 and L = 1 state with a large in-plane orbital moment, and this result well explains the experimental large effective magnetic moment of RuCl3 and the strong in-plane magnetization. The present work demonstrates the contrasting spin-orbital states and the varying properties of RuI3 and RuCl3.

Automated summary

The electronic and magnetic properties of RuI3 and RuCl3 were investigated using first-principles calculations. RuI3 was found to be a paramagnetic metal, while RuCl3 exhibited Mott-insulating behavior. The spin-orbital states of the Ru3+ ion in RuI3 and RuCl3 were also determined. The transition from RuI3 bulk to monolayer resulted in a metal-insulator transition, primarily due to band narrowing and altered Ru-I hybridization. This study provides insights into the contrasting properties and spin-orbital states of RuI3 and RuCl3.