Supercooling and fragile glassiness in a dipolar kagome Ising magnet


Type
Article
Change log
Authors
Hamp, J 
Moessner, R 
Castelnovo, Claudio  ORCID logo  https://orcid.org/0000-0003-1752-6343
Abstract

We study equilibration and ordering in the classical dipolar kagome Ising antiferromagnet, which we show behaves as a disorder-free fragile spin glass. By identifying an appropriate order parameter, we demonstrate a transition to the ordered state proposed by Chioar et al. [Phys. Rev. B 93, 214410 (2016)] with a 12-site unit cell that breaks time-reversal and sublattice symmetries, and further provide evidence that the nature of the transition is first order. Upon approaching the transition, the spin dynamics slow dramatically. The system readily falls out of equilibrium, overshooting the transition and entering a supercooled liquid regime. Using extensive Monte Carlo simulations, we show that the system exhibits super-Arrhenius behaviour above the ordering transition. The relaxation time diverges according to a Vogel-Fulcher form at a finite `glass transition' temperature in the supercooled regime. Such behaviour, characteristic of fragile glasses, is particularly remarkable as the model is free of quenched disorder, does not straightforwardly conform to the avoided criticality paradigm, and is simple and eminently realisable in engineered nanomagnetic arrays.

Description
Keywords
cond-mat.str-el, cond-mat.str-el, cond-mat.dis-nn, cond-mat.stat-mech
Journal Title
Physical Review B
Conference Name
Journal ISSN
2469-9950
2469-9969
Volume Title
98
Publisher
American Physical Society (APS)
Sponsorship
Engineering and Physical Sciences Research Council (EP/K028960/1)
Engineering and Physical Sciences Research Council (EP/P034616/1)
Engineering and Physical Sciences Research Council (EP/M007065/1)