Random Exchange Quantum Heisenberg Chains

Abstract

The one-dimensional quantum Heisenberg model with random $\pm J$ bonds is studied for $S=\frac{1}{2}$ and $S=1$. The specific heat and the zero-field susceptibility are calculated by using high-temperature series expansions and quantum transfer matrix method. The susceptibility shows a Curie-like temperature dependence at low temperatures as well as at high temperatures. The numerical results for the specific heat suggest that there are anomalously many low-lying excitations. The qualitative nature of these excitations is discussed based on the exact diagonalization of finite size systems.

13 pages, RevTex, 12 figures available on request ([email protected])

References in corpus (1)

• Random Exchange Disorder in the Spin-1/2 XXZ Chain

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