77 research outputs found
Scaling and data collapse from local moments in frustrated disordered quantum spin systems
Recently measurements on various spin-1/2 quantum magnets such as
HLiIrO, LiZnMoO, ZnCu(OH)Cl and 1T-TaS
-- 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 with at small , with (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 -dependent subdominant term enforced by Maxwell's relations.Comment: v2. Expanded argument in Appendix 2 and revised for clarity. v3.
Fixed typo in Fig 3 caption. Main text 4 pages 4 figures, Appendix 6 pages 1
figur
Single Crystal Growth Tricks and Treats
Single crystal growth is a widely explored method of synthesizing materials
in the solid state. The last few decades have seen significant improvements in
the techniques used to synthesize single crystals, but there has been
comparatively little discussion on ways to disseminate this knowledge. We aim
to change that. Here we describe the principles of known single crystal growth
techniques as well as lesser-known variations that have assisted in the
optimization of defect control in known materials. We offer a perspective on
how to think about these synthesis methods in a grand scheme. We consider the
temperature interdependence with the reaction time as well as ways to carry out
synthesis to scale up and address some outstanding synthesis challenges. We
hope our descriptions will aid in technological advancements as well as further
developments to gain even better control over synthesis
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