From order to randomness: Onset and evolution of the random-singlet state in bond-disordered BaCu${}_2$(Si${}_{1-x}$Ge${}_x$)${}_2$O${}_7$ spin-chain compounds

Abstract

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 BaCu${}_2$Si${}_2$O${}_7$, a typical spin-1/2 chain system, we investigate a series of compounds with different degrees of bond disorder, where the systematic replacement of Si with Ge results in a re-modulation of the Cu${}^{2+}$ exchange interactions. By combining magnetometry measurements with nuclear magnetic resonance studies we follow the evolution of the disorder-related properties from the well-ordered BaCu${}_2$Si${}_2$O${}_7$ to the maximally disordered BaCu${}_2$SiGeO${}_7$. Our data indicate that already a weak degree of disorder of only 5% Ge, apart from reducing the 3D magnetic ordering temperature $T_{\mathrm{N}}$ 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 $T_{\mathrm{N}}$ is reduced, yet its influence is clearly manifest, particularly in the features of NMR relaxation data.

arXiv comment7 pages, 5 figures

References in corpus (22)

• Many-body localization: an introduction and selected topics
• Quantum Glassiness
• Thermodynamics of Spin S = 1/2 Antiferromagnetic Uniform and Alternating-Exchange Heisenberg Chains
• Quantum criticality and universal scaling of a quantum antiferromagnet
• Infinite-randomness quantum Ising critical fixed points
• Diffusion and ballistic transport in one-dimensional quantum systems
• Critical Properties of gapped spin-1/2 chains and ladders in a magnetic field
• Ballistic heat transport of quantum spin excitations as seen in SrCuO2
• Spinons in the strongly correlated copper oxide chains in SrCuO2
• 17O NMR study of q=0 spin excitations in a nearly ideal S=1/2 1D Heisenberg antiferromagnet, Sr2CuO3, up to 800 K
• NMR relaxation in half-integer antiferromagnetic spin chains
• Dirty-boson physics with magnetic insulators
• Magnetic order and spin-waves in the quasi-1D S=1/2 antiferromagnet $\mathbf{BaC}{\mathbf{u}}_2\mathbf{S}{\mathbf{i}}_2{\mathbf{O}}_7$
• Distribution of NMR relaxations in a random Heisenberg chain
• Quantum critical dynamics of a S = 1/2 antiferromagnetic Heisenberg chain studied by 13C-NMR spectroscopy
• Dynamical properties of the $S=\frac{1}{2}$ random Heisenberg chain
• Disorder-induced Spin Gap in the Zigzag Spin-1/2 Chain Cuprate Sr_{0.9}Ca_{0.1}CuO_2
• Local spin relaxation within the random Heisenberg chain
• Dimensional crossover of spin chains in a transverse staggered field: an NMR study
• Impact of strong disorder on the static magnetic properties of the spin-chain compound BaCu2SiGeO7
• The effect of different in-chain impurities on the magnetic properties of the spin chain compound SrCuO${}_2$ probed by NMR
• Inhomogeneous ordering in weakly coupled Heisenberg $S=1/2$ chains with random bonds

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• Thermal Properties of Rung Disordered Two-leg Quantum Spin Ladders: Quantum Monte Carlo Study
• Possible realization of a randomness-driven quantum disordered state in an S = 1/2 antiferromagnet Sr3CuTa2O9
• $s$-wave superconductivity in the noncentrosymmetric W${}_3$Al${}_2$C superconductor: An NMR study
• Thermodynamic properties of disordered quantum spin ladders