2007/11/30 by Yen Lee Loh, Dao‐Xin Yao, Dao-Xin Yao +2
Physics and Astronomy · #Advanced Condensed Matter Physics #Physics of Superconductivity and Magnetism #Theoretical and Computational Physics #cond-mat.other #cond-mat.stat-mech
paper · pdf · doi:10.1103/physrevb.77.134402
published as Phys. Rev. B 77, 134402 (2008) · 15 pages, 16 figures, published version (http://www.physics.purdue.edu/~dyao/)
openalex publication_date 2008/04/02 · arxiv created 2008/04/28 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
A new class of two-dimensional magnetic materials Cu9X2(cpa)6\ensuremath⋅xH2O (cpa=2-carboxypentonic acid; X=F,Cl,Br) was recently fabricated in which Cu sites form a triangular kagome lattice (TKL). As the simplest model of geometric frustration in such a system, we study the thermodynamics of Ising spins on the TKL using exact analytic method as well as Monte Carlo simulations. We present the free energy, internal energy, specific heat, entropy, sublattice magnetizations, and susceptibility. We describe the rich phase diagram of the model as a function of coupling constants, temperature, and applied magnetic field. For frustrated interactions in the absence of applied field, the ground state is a spin liquid phase with residual entropy per spin s0∕kB=(1)/(9)\phantom\rule0.2em0exln\phantom\rule0.2em0ex72\ensuremath≈0.4752… . In weak applied field, the system maps to the dimer model on a honeycomb lattice, with residual entropy 0.0359 per spin and quasi-long-range order with power-law spin-spin correlations that should be detectable by neutron scattering. The power-law correlations become exponential at finite temperatures, but the correlation length may still be long.