Electronic Properties of α−RuCl3 in Proximity to Graphene

Abstract

In the pursuit of developing routes to enhance magnetic Kitaev interactions in α-RuCl3, as well as probing doping effects, we investigate the electronic properties of α-RuCl3 in proximity to graphene. We study α-RuCl3/graphene heterostructures via ab initio density functional theory calculations, Wannier projection and non-perturbative exact diagonalization methods. We show that α-RuCl3 becomes strained when placed on graphene and charge transfer occurs between the two layers, making α-RuCl3 (graphene) lightly electron-doped (hole-doped). This gives rise to an insulator to metal transition in α-RuCl3 with the Fermi energy located close to the bottom of the upper Hubbard band of the t2g manifold. These results suggest the possibility of realizing metallic and even exotic superconducting states. Moreover, we show that in the strained α-RuCl3 monolayer the Kitaev interactions are enhanced by more than 50% compared to the unstrained bulk structure. Finally, we discuss scenarios related to transport experiments in α-RuCl3/graphene heterostructures. arXiv:1908.04793v2 [cond-mat.str-el]

Charge-Transfer Plasmon Polaritons at Graphene/α-RuCl3 Interfaces

“…This value is consistent with previous measurements of the Hall resistance ( n = 2.8 × 10 13 cm –2 ) 8 and is in good agreement with theoretical expectation ( Figure 1 c,d). 27 We note that the agreement between the experimental and model dispersions was improved by assuming that the topmost layer of α-RuCl 3 possesses additional optical conductivity ( Figure S5 ) compared to that of undoped α-RuCl 3 . 28 Hence, our data establish the notion of large interfacial doping and enhanced optical conductivity in α-RuCl 3 as suggested by DFT calculations ( Figure 1 c,d).…”

Kitaev Spin Liquid in 3d Transition Metal Compounds

“…The JT physics, even though rarely explored, is universal in spin-orbit Mott insulators and plays an important part when describing the low energy physics such as in Sr 2 IrO 4 and Ca 2 RuO 4 71 . Through the pseudospin-lattice coupling, the JT effect generates new terms or renormalizes the coupling constants in the Hamiltonian 8,71,72 through modifying the wave functions. For instance, the symmetry allowed Γ term is originated from the non-zero trigonal crystal field as shown in Eq.…”

Designer quantum matter in van der Waals heterostructures

“…It has been proposed that monolayer RuCl 3 on graphene (illustrated in Fig. 3d) would result in a system with enhanced Kitaev type interactions [75,76]. By using ab initio calculations, it was shown that the RuCl 3 becomes strained and doped in this heterostructure.…”

“…3a) can be potentially adiabatically connected to quantum spin-liquid states realized in α-RuCl 3 (RuCl 3 ) [74,89,[91][92][93], and thus in the following we will focus on this compound. RuCl 3 is a layered Mott insulator with significant spin-orbit interactions that is in the close proximity to the quantum spinliquid ground state [66,74,75]. However, these materials often host complex Hamiltonians having several contributions beyond the Kitaev exchange, including first, second and third neighbor exchange, and symmetric off-diagonal exchange [74,[94][95][96].…”