Quantum Monte Carlo Study of Random Antiferromagnetic Heisenberg Chain.pdf

8 Quantum Monte Carlo Study of 9 Random Antiferromagnetic Heisenberg Chain∗ 9 1 S. Todo, K. Kato, and H. Takayama r a M Institute for Solid State Physics, University of Tokyo, Tokyo 106-8666, Japan 9 Abstract. Effects of randomness on the spin- 1 and 1 antiferromagnetic Heisen- 2 ] berg chains are studied using the quantum Monte Carlo method with the n n continuous-time loop algorithm. We precisely calculated the uniform suscep- - tibility, string order parameter, spatial and temporal correlation length, and s i the dynamical exponent, and obtained a phase diagram. The generalization of d the continuous-time loop algorithm for the systems with higher-S spins is also . t presented. a m - 1. Introduction d n Low-energy properties of one-dimensional quantum Heisenberg antiferromag- o nets have been of great interest for many years. Particularly, effects of random- c [ ness on ground states with strong quantum fluctuations, such as the so-called Haldane state, have been studied extensively in recent years [1-5]. 1 In the present work, we investigated S = 1 and S = 1 random antiferro- v 2 8 magnetic Heisenberg chains by means of the quantum Monte Carlo method 8 with the continuous-time loop algorithm [6-9]. To this end, we first generalize 0