Spin Glasses: Experimental Signatures and Salient Outcomes

Abstract

Within the wide class of disordered materials, spin glasses occupy a special place because of their conceptually simple definition of randomly interacting spins. Their modelling has triggered spectacular developments of out-of-equilibrium statistical physics, as well analytically as numerically, opening the way to a new vision of glasses in general. "Real" spin glasses are disordered magnetic materials which can be very diverse from the chemist's point of view, but all share a number of common properties, laying down the definition of generic spin glass behaviour. This paper aims at giving to non-specialist readers an idea of what spin glasses are from an experimentalist's point of view, describing as simply as possible their main features as they can be observed in the laboratory, referring to numerous detailed publications for more substantial discussions and for all theoretical developments, which are hardly sketched here. We strived to provide the readers who are interested in other glassy materials with some clues about the potential of spin glasses for improving their understanding of disordered matter. At least, arousing their curiosity for this fascinating subject will be considered a success.

Structure and magnetic studies of geometrically frustrated disordered pyrochlores A$_{2}$Zr$_{2}$O$_{7}$: (A = Eu, Gd, Er)

“…7b) given by τ = τ o exp(E a /k B T f ), where E a , k B , τ represents the activation energy, Boltzmann constant and relaxation time respectively. This fit yields parameters value as τ ∼ 10 −10 s and E a = 512(34) K which is in close agreement to spin glass systems (τ ∼ 10 −11 -10 −13 s) [33,34]. However, the characterization of the spin-glass state by fit to these models is somewhat inclusive due to the absence of irreversibility in dc magnetization.…”

What Can Spin Glass Theory and Analogies Tell Us About Ferroic Glasses?

“…The key ingredients to permit such glassy behaviour appear to be frustrated interactions and quenched disorder, as has often been expressed before. Probing these The simple analogies considered here suggest further conceptual transfers between different ferroic materials and further experimental investigations; for further discussion concerning characteristic experimental aspects of spin glasses see [97]; for a complemetary recent discussion of relaxors see [54].…”

Fluctuation-guided search in quantum annealing

“…The exact nature of the phase which is realized in the large system limit for s = 1 is not immediately clear so therefore neither is the nature of the transition and the factors which affect its location. The fact that annealing from the paramagnetic precursor tends not to find the ground state provides weak evidence against this phase transition being a simple transition into a ferromagnetic phase and is more consistent with a spin glass [43] or a Griffiths-type phase transition [44,45].…”