Spinon Fermi Surface in a Cluster Mott Insulator Model on a Triangular Lattice and Possible Application to 1T−TaS2

Abstract

1T-TaS_{2} is a cluster Mott insulator on the triangular lattice with 13 Ta atoms forming a star of David cluster as the unit cell. We derive a two-dimensional XXZ spin-1/2 model with a four-spin ring exchange term to describe the effective low energy physics of a monolayer 1T-TaS_{2}, where the effective spin-1/2 degrees of freedom arises from the Kramers degenerate spin-orbital states on each star of David. A large scale density matrix renormalization group simulation is further performed on this effective model and we find a gapless spin liquid phase with a spinon Fermi surface at a moderate to large strength region of the four-spin ring exchange term. All peaks in the static spin structure factor are found to be located on the "2k_{F}" surface of a half-filled spinon on the triangular lattice. Experiments to detect the spinon Fermi surface phase in 1T-TaS_{2} are discussed.

Stable Flatbands, Topology, and Superconductivity of Magic Honeycomb Networks

“…The interlayer interaction has been suggested to be important in metallization and SC in 1T-TaS 2 . However, we remark that there are plenty of experimental data and theory 31,33 suggesting that the main physics is essentially two-dimensional. For example, the resistivity along c-axis is much larger, e.g., by 500 times, 50 than the intralayer resistivity 50,51 and anisotropic two-dimensional charge transfer is observed for the NC-CDW state.…”

“…This state is the correlationdriven Mott insulator, 29 which has been suspected to be the long-sought spin liquid. 30,31 When the C-CDW ordering is slightly suppressed by pressure or doping, then the domain walls appear inbetween the locally chargeordered domains, i.e., it enters into the NC-CDW state. If the pressure or doping increase further, the SC emerges from this NC-CDW state.…”

Vanishing Wilson ratio as the hallmark of quantum spin-liquid models

“…These quantities are mostly extracted from experiments on KL systems, the prominent example being herbertsmithite [27][28][29][30][31], but also related compounds in the same class [32][33][34][35][36][37]. Another example are organic compounds where the relevant lattice is triangular [38][39][40][41] as well as charge-density-wave system 1T-TaS 2 , recently established as SL with composite S = 1/2 spins on TL [42][43][44][45]. The basic spin exchange scale in most of these systems is modest and, as a consequence, the whole T range is experimentally accessible which allows for the test of the whole range of spin excitations.…”

Similarity of thermodynamic properties of the Heisenberg model on triangular and kagome lattices

“…Another class are organic compounds, as κ-(ET) 2 Cu 2 (CN) 3 [16][17][18][19], where the spins reside on a triangular lattice. Recently, the charge-density-wave system 1T-TaS 2 , which is a Mott insulator without magnetic LRO and shows spin fluctuations at T > 0 [20][21][22][23], has been added into this family.…”