Scaling and data collapse from local moments in frustrated disordered quantum spin systems

Journal Article · 21 October 2018 · Nature Communications

DOI: https://doi.org/10.1038/s41467-018-06800-2 · OSTI ID:1483398

Kimchi, Itamar  ^[1]; Sheckelton, John P. ^[2]; McQueen, Tyrel M. ^[3]; Lee, Patrick A. ^[4]

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1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Physics; Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139
2. Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Physics and Astronomy, and the Inst. for Quantum Matter
3. Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Physics and Astronomy, and the Inst. for Quantum Matter, and Dept. of Materials Science and Engineering
4. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Physics

Recently measurements on various spin–1/2 quantum magnets such as H₃LiIr₂O₆, LiZn₂Mo₃O₈, ZnCu₃(OH)₆Cl₂ and 1T-TaS₂—all described by magnetic frustration and quenched disorder but with no other common relation—nevertheless showed apparently universal scaling features at low temperature. In particular the heat capacity C[H, T] in temperature T and magnetic field H exhibits T/H data collapse reminiscent of scaling near a critical point. Here we propose a theory for this scaling collapse based on an emergent random-singlet regime extended to include spin-orbit coupling and antisymmetric Dzyaloshinskii-Moriya (DM) interactions. We derive the scaling C[H, T]/T ~ H-^γF_q[T/H] with F_q[x] = x^q at small x, with q ϵ {0, 1, 2} an integer exponent whose value depends on spatial symmetries. The agreement with experiments indicates that a fraction of spins form random valence bonds and that these are surrounded by a quantum paramagnetic phase. We also discuss distinct scaling for magnetization with a q-dependent subdominant term enforced by Maxwell’s relations.

• Research Organization: Johns Hopkins Univ., Baltimore, MD (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• Grant/Contract Number: FG02-03ER46076; FG02-08ER46544
• OSTI ID: 1483398
• Journal Information: Nature Communications, Journal Name: Nature Communications Journal Issue: 1 Vol. 9; ISSN 2041-1723
• Publisher: Nature Publishing GroupCopyright Statement
• Country of Publication: United States
• Language: English