By using Lanczos exact diagonalization and quantum Monte Carlo combined with stochastic analytic continuation,we study the dynamical properties of the S=1 antiferromagnetic Heisenberg chain with different strengths of...By using Lanczos exact diagonalization and quantum Monte Carlo combined with stochastic analytic continuation,we study the dynamical properties of the S=1 antiferromagnetic Heisenberg chain with different strengths of bond disorder.In the weak disorder region,we find weakly coupled bonds which can induce additional low-energy excitation below the one-magnon mode.As the disorder increases,the average Haldane gap closes at δ_(∆)~0.5 with more and more low-energy excitations coming out.After the critical disorder strength δ_(C)~1,the system reaches a random-singlet phase with prominent sharp peak atω=0 and broad continuum atω>0 of the dynamic spin structure factor.In addition,we analyze the distribution of random spin domains and numerically find three kinds of domains hosting effective spin-1/2 quanta or spin-1 sites in between.These“spins”can form the weakly coupled longrange singlets due to quantum fluctuation which contribute to the sharp peak atω=0.展开更多
基金D.X.Y.,J.K.F,and J.H.H are supported by NKRDPC-2017YFA0206203,NKRDPC-2018YFA0306001,NSFC-11974432,GBABRF-2019A1515011337Shenzhen Institute for Quantum Science and Engineering,and Leading Talent Program of Guangdong Special Projects+1 种基金H.Q.W.is supported by NSFC-11804401the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(Grant No.2021qntd27).
文摘By using Lanczos exact diagonalization and quantum Monte Carlo combined with stochastic analytic continuation,we study the dynamical properties of the S=1 antiferromagnetic Heisenberg chain with different strengths of bond disorder.In the weak disorder region,we find weakly coupled bonds which can induce additional low-energy excitation below the one-magnon mode.As the disorder increases,the average Haldane gap closes at δ_(∆)~0.5 with more and more low-energy excitations coming out.After the critical disorder strength δ_(C)~1,the system reaches a random-singlet phase with prominent sharp peak atω=0 and broad continuum atω>0 of the dynamic spin structure factor.In addition,we analyze the distribution of random spin domains and numerically find three kinds of domains hosting effective spin-1/2 quanta or spin-1 sites in between.These“spins”can form the weakly coupled longrange singlets due to quantum fluctuation which contribute to the sharp peak atω=0.
