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Low-lying excitations and thermodynamics of an antiferromagnetic Heisenberg fractal system of a dimension between one and two

A. Voigt·J. Richter·P. Tomczak
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Abstract

We investigate a frustrated Heisenberg spin-1/2 antiferromagnet on a fractal lattice of dimension d=ln3/ln2 (Sierpinski gasket). Calculations were performed using (a) exact diagonalization of all eigenstates and eigenvectors for systems up to N=15 and (b) the Decoupled-Cell Quantum-Monte-Carlo method for systems up to N=366. We present the low-lying spectrum and the specific heat. The specific heat shows a second maximum in the low-temperature region. This behavior is similar to the behavior of the quantum Heisenberg antiferromagnet on a kagome lattice and suggests a disordered ground state and a spin gap in the considered system.

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A. Voigt, J. Richter, P. Tomczak. 1997-10-22. Low-lying excitations and thermodynamics of an antiferromagnetic Heisenberg fractal system of a dimension between one and two. https://doi.org/10.1016/s0304-8853(97)00280-1

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