Monte Carlo Study of the Separation of Energy Scales in Quantum Spin 1/2 Chains with Bond Disorder

Abstract

One-dimensional Heisenberg spin 1/2 chains with random ferro- and antiferromagnetic bonds are realized in systems such as $S{r}_{3}CuP{t}_{1-x}I{r}_x{O}_6$. We have investigated numerically the thermodynamic properties of a generic random bond model and of a realistic model of $S{r}_{3}CuP{t}_{1-x}I{r}_x{O}_6$ by the quantum Monte Carlo loop algorithm. For the first time we demonstrate the separation into three different temperature regimes for the original Hamiltonian based on an exact treatment, especially we show that the intermediate temperature regime is well-defined and observable in both the specific heat and the magnetic susceptibility. The crossover between the regimes is indicated by peaks in the specific heat. The uniform magnetic susceptibility shows Curie-like behavior in the high-, intermediate- and low-temperature regime, with different values of the Curie constant in each regime. We show that these regimes are overlapping in the realistic model and give numerical data for the analysis of experimental tests.

7 pages, 5 eps-figures included, typeset using JPSJ.sty, accepted for publication in J. Phys. Soc. Jpn. 68, Vol. 3. (1999)

References in corpus (1)

• Low-Temperature Scaling Regime of Random Ferromagnetic-Antiferromagnetic Spin Chains

Cited by in corpus (4)

• The Loop Algorithm
• Thermodynamics of Random Ferromagnetic Antiferromagnetic Spin-1/2 Chains
• Modified spin-wave study of random antiferromagnetic-ferromagnetic spin chains
• Spin Waves in Random Spin Chains