期刊
PHYSICAL REVIEW B
卷 90, 期 1, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevB.90.014205
关键词
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资金
- ANR [13-JS04-0005-01, 2010-BLANC-041902]
We study the dynamics of excitations in a system of 0(N) quantum rotors in the presence of random fields and random anisotropies. Below the lower critical dimension d(1c) = 4 the system exhibits a quasi-long-range order with a power-law decay of correlations. At zero temperature the spin waves are localized at the length scale L-loc beyond which the quantum tunneling is exponentially suppressed, c similar to e(-(L/Lloc)2(theta+1)). At finite temperature T the spin waves propagate by thermal activation over energy barriers that scale as L-theta. Above d(1c) the system undergoes an order-disorder phase transition with activated dynamics such that the relaxation time grows with the correlation length xi as tau similar to e(C xi theta/T) at finite temperature and as tau similar to e(C'xi 2(theta+1)/h2) in the vicinity of the quantum critical point.
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