### Session Y27: Focus Session: Kagome Magnets

11:15 AM–2:15 PM, Friday, March 14, 2008
Morial Convention Center Room: 219

Chair: Ying Chen, National Institute of Standards and Technology

Abstract ID: BAPS.2008.MAR.Y27.8

### Abstract: Y27.00008 : Thermodynamics of Ising Spins on the Triangular Kagome Lattice

12:39 PM–12:51 PM

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#### Authors:

Yen Lee Loh
(Purdue University)

Daoxin Yao
(Purdue University)

Erica W. Carlson
(Purdue University)

In the compounds $\mbox{Cu}_{9}\mbox{X}_2(\mbox{cpa})_{6}\cdot x\mbox{H}_2\mbox{O}$ (cpa=2-carboxypentonic acid; X=F,Cl,Br), the Cu spins form a fascinating and unique pattern called a triangular kagome lattice (TKL). We present a detailed study of Ising spins on such a lattice using exact methods and Monte Carlo simulation. We calculate the free energy, internal energy, specific heat, entropy, sublattice magnetizations, and susceptibility, and we find a rich phase diagram as a function of coupling constants, temperature, and applied magnetic field. In the frustrated regime at $T=0$, the system effectively decouples into independent degrees of freedom, giving residual entropy $s_0=\frac{1}{9} \ln 72$ per spin and correlation length $\xi=0$ -- an interesting contrast with the triangular and kagome lattice Ising models. Applying a field induces a critical phase (related to the honeycomb lattice dimer model) that has irrational entropy $0.0359$ per spin and $1/r^2$ correlations that should be detectable by neutron scattering.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2008.MAR.Y27.8