From order to randomness: Onset and evolution of the random-singlet state in bond-disordered BaCu2(Si1-xGex)(2)O-7 spin-chain compounds

Article

关键词: NUCLEAR MAGNETIC RELAXATION;    QUANTUM;   

DOI  :  10.1103/PhysRevB.99.035116

来源: SCIE

【 摘 要 】

Heisenberg-type spin-chain materials have been extensively studied over the years, yet not much is known about their behavior in the presence of disorder. Starting from BaCu2Si2O7 , a typical spin-1/2 chain system, we investigate a series of compounds with different extents of bond disorder, where the systematic replacement of Si with Ge results in a remodulation of the Cu2+ exchange interactions. By combining magnetometry measurements with nuclear magnetic resonance studies, we follow the evolution of the disorder-related properties from the well-ordered BaCu2Si2O7 to the maximally disordered BaCu2SiGeO7 . Our data indicate that already a weak degree of disorder of only 5% Ge, apart from reducing the three-dimensional magnetic ordering temperature T-N quite effectively, induces a qualitatively different state in the paramagnetic regime. At maximum disorder our data indicate that this state may be identified with the theoretically predicted random singlet (RS) state. With decreasing disorder the extension of the RS regime at temperatures above T-N is reduced, yet its influence is clearly manifest, particularly in the features of nuclear magnetic resonance relaxation data.

【 授权许可】

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