Nearest-neighbor Kitaev exchange blocked by charge order in electron-doped α−RuCl3

Abstract

A quantum spin-liquid might be realized in α-RuCl3, a honeycomb-lattice magnetic material with substantial spin-orbit coupling. Moreover, α-RuCl3 is a Mott insulator, which implies the possibility that novel exotic phases occur upon doping. Here, we study the electronic structure of this material when intercalated with potassium by photoemission spectroscopy, electron energy loss spectroscopy, and density functional theory calculations. We obtain a stable stoichiometry at K0.5RuCl3. This gives rise to a peculiar charge disproportionation into formally Ru 2+ (4d 6 ) and Ru 3+ (4d 5 ). Every Ru 4d 5 site with one hole in the t2g shell is surrounded by nearest neighbors of 4d 6 character, where the t2g level is full and magnetically inert. Thus, each type of Ru sites forms a triangular lattice and nearest-neighbor interactions of the original honeycomb are blocked.

Quantum spin liquids

“…And, consistent with the organics and herbertsmithite, disorder should play a significant role as well, particularly due to the presence of stacking faults (95). Finally, based on the evidence that a-RuCl 3 exhibits spin liquid behavior, it is of great interest to study the physical properties of electron/hole doped variants (96). It is worth noting that while doping a-RuCl 3 via chemical reduction or oxidation, one should always be careful to perform the reaction under an inert and non-nitrogen atmosphere because Ru complexes react with nitrogen.…”

Magnetoelastic coupling and effects of uniaxial strain in α−RuCl3 from first principles

“…Nevertheless, the physics of such extended Kitaev models have lead to countless interesting unconventional phenomena in these materials with arguably the most prominent example being α-RuCl 3 . With the goal of tuning away from its antiferromagnetic zigzag order and possibly to a Kitaev QSL, various routes have been considered, including chemical doping [18][19][20], graphene substrates [21][22][23][24], hydrostatic pressure [25][26][27][28][29] and magnetic fields [30][31][32][33][34][35][36]. In the case of hydrostatic pressure, dimerization quickly destroys the j eff = 1/2 picture [25,29] such that no Kitaev QSL can occur.…”

Comparing the influence of Floquet dynamics in various Kitaev-Heisenberg materials

“…Tuning these materials from zig-zag to the KSL has been a focal point of theoretical and experimental research. While tuning via pressure [14][15][16], magnetic field [17][18][19][20][21], graphen substrates [22] and chemical doping [23][24][25] has been investigated extensively, the approach of driving the Kitaev phase via a periodic light field is yet relatively unexplored.…”