Ba8CoNb6O24: A spin-12triangular-lattice Heisenberg antiferromagnet in the two-dimensional limit

Magnetic and charge susceptibilities in the half-filled triangular lattice Hubbard model

“…Experimental evidence on several organic materials, including κ-(BEDT-TTF) 2 Cu 2 (CN) 3 [1,2], EtMe 3 Sb[Pd(dmit) 2 ] 2 [3][4][5], and κ-H 3 (Cat-EDT-TTF) 2 [6], suggests that these compounds are close to a two-dimensional triangular structure and exhibit interesting electron correlation behavior including, potentially, a quantum spin liquid phase [7] in the ground state [8]. These compounds, as well as the low energy physics of the fully isotropic triangular material Ba 8 CoNb 6 O 24 [9], may be described by a half-filled single orbital Hubbard model on a triangular two-dimensional lattice, with an on-site Coulomb interaction strength comparable to or larger than the bandwidth [10].…”

“…These compounds, as well as the low energy physics of the fully isotropic triangular material Ba 8 CoNb 6 O 24 [9], may be described by a half-filled single orbital Hubbard model on a triangular two-dimensional lattice, with an on-site Coulomb interaction strength comparable to or larger than the bandwidth [10].Because of the subtle competition of metallic, ordered, and spin liquid phases in the ground state, this model has been studied extensively with a wide range of numerical tools, including exact diagonalization (ED) [11][12][13], density matrix renormalization group theory (DMRG) [8], variational Monte Carlo (VMC) [14][15][16][17], variational cluster approximation [18][19][20], strong coupling expansions [21], path integral renormalization group techniques [22], and cluster dynamical mean field theory (DMFT) in the cellular [23][24][25][26][27] and dynamical cluster [28,29] variants. The focus in most of these studies has been on the precise location of the phase boundaries, ordering (or the absence thereof), and on the nature of these phases.Experimentally, much of our knowledge about correlated triangular systems is obtained from single-and two-particle scattering experiments such as photoemission [30], Raman spectroscopy [31], nuclear magnetic resonance (NMR) [2,32], or inelastic neutron scattering [9,33]. To understand these experimental results, it is necessary to calculate the corresponding response functions as a function of energy and momentum.…”

Exact diagonalization and cluster mean-field study of triangular-lattice XXZ antiferromagnets near saturation

“…A possible option is a family of Cobased compounds [11,12,14,15,19], which can possess an effective XXZ anisotropy due to the strong spinorbit coupling. For example, the latest estimation of the anisotropy parameter J/J z in Ba 3 CoSb 2 O 9 (S = 1/2) ranges from J/J z ≈ 1.18 to 1.3 [18,29,42].…”

Disorder-Induced Mimicry of a Spin Liquid in YbMgGaO4

“…Among the latest experimental discoveries [14,15], a rare-earth triangular-lattice antiferromagnet YbMgGaO 4 has recently emerged as a new candidate for a quantum spin liquid of the effective spin-1/2 degrees of freedom of Yb 3+ ions [43,44]. It has been argued that the spin-orbit origin of its magnetic properties and the pseudo-spin nature of the low-energy states with highly anisotropic effective spin interactions may potentially open a new route to realizing quantum spin liquids [44][45][46].…”

“…Jm, 75.40.Gb, 78.70.Nx Dating back to Wannier's pioneering study of the Ising model [1], triangular lattice models and materials with frustrating antiferromagnetic interactions have served as fertile playgrounds for new ideas [2][3][4][5][6][7][8][9][10]. These systems continue to draw significant experimental [11][12][13][14][15] and theoretical interest because they exhibit many intriguing novel ordered states [16][17][18][19][20][21][22] and unusual continuumlike spectral features [23][24][25][26][27][28][29][30][31] and especially because they provide a setting for spin-liquid states [32][33][34][35][36][37][38][39][40][41][42].Among the latest experimental discoveries [14,15], a rare-earth triangular-lattice antiferromagnet YbMgGaO 4 has recently emerged as a new candidate for a quantum spin liquid of the effective spin-1/2 degrees of freedom of Yb 3+ ions [43,44]. It has been argued that the spin-orbit origin of its magnetic properties and the pseudo-spin nature of the low-energy states with highly anisotropic effective spin interactions may potentially open a new route to realizing quantum spin liquids [44][45][46].…”