Ground-state energy density, susceptibility, and Wilson ratio of a two-dimensional disordered quantum spin system

Article

关键词: PHASE-TRANSITIONS;    HEISENBERG-ANTIFERROMAGNET;    CRITICAL-BEHAVIOR;    MONTE-CARLO;    ABSENCE;   

DOI  :  10.1103/PhysRevB.102.214206

来源: SCIE

【 摘 要 】

A two-dimensional (2D) spin-1/2 antiferromagnetic Heisenberg model with a specific kind of quenched disorder is investigated, using the first-principles nonperturbative quantum Monte Carlo calculations (QMCs). The employed disorder distribution has a tunable parameter p which can be considered as a measure of randomness (p = 0 correponds to the clean model). Through large-scale QMCs, the dynamic critical exponents z, the ground-state energy densities E-0, and the Wilson ratios W of various p are determined with high precision. Interestingly, we find that the p dependencies of z and W are likely to be complementary to each other. For instance, while the z values of 0.4 <= p <= 0.9 match well among themselves and are statistically different from that of p = 0, the W values for p < 0.7 are in reasonably good agreement with W similar to 0.1243 of the clean case. Surprisingly, our study indicates that a threshold of randomness, p(w), associated with W exists. In particular, beyond this threshold the magnitude of W grows with p. This is somehow counterintuitive since one expects the spin correlations should diminish accordingly Similarly, there is a threshold p(z) related to z after which a constant value is obtained for z. The results presented here are not only interesting from a theoretical perspective but also can serve as benchmarks for future related studies.

【 授权许可】

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