Scaling of Memories and Crossover in Glassy Magnets

Abstract

Glassiness is ubiquitous and diverse in characteristics in nature. Understanding their differences and classification remains a major scientific challenge. Here, we show that scaling of magnetic memories with time can be used to classify magnetic glassy materials into two distinct classes. The systems studied are high temperature superconductor-related materials, spin-orbit Mott insulators, frustrated magnets, and dilute magnetic alloys. Our bulk magnetization measurements reveal that most densely populated magnets exhibit similar memory behavior characterized by a relaxation exponent of . This exponent is different from of dilute magnetic alloys that was ascribed to their hierarchical and fractal energy landscape, and is also different from of the conventional Debye relaxation expected for a spin solid, a state with long range order. Furthermore, our systematic study on dilute magnetic alloys with varying magnetic concentration exhibits crossovers among the two glassy states and spin solid.

Memory Effect in Spin Glass Ni0.45Mn0.55TiO3

“…These results reveal that the tw dependence of the memory effect in Ni0.45Mn0.55TiO3 cannot be explained by a simple exponential function ( =1), but rather by a stretched one (0<<1). Similar results were reported in different spin glass systems, such as CuMn [10]. The present data illustrate another example of, and help to further understand, the memory effect in spin glass systems.…”

High-resolution neutron spectroscopy using backscattering and neutron spin-echo spectrometers in soft and hard condensed matter

“…These systems exhibit nonequilibrium transitions from a fluid-like to a solid-like state. Jamming of particles or spins, in local mimima of an exotic energy landscape, precludes further exploration of the phase space 128,129 , but the characteristic sudden arrest of their dynamics are readily probed using NSE and backscattering techniques 130,131 . Glass transition, gelation and aggregation are all closely related and only the wide coverage of Q and energy space provided by these neutron techniques can help to distinguish such dynamics 132 .…”

Precipitating ordered skyrmion lattices from helical spaghetti and granular powders

“…For misoriented helical states, including the skyrmion state, the intersection of two domains may leave neither able to propagate or reorient, becoming trapped in a jammed state, analogous to magnetic spin ice or frustrated magnets. [24,25] As a result (Fe, Co)Si can possess a complex magnetic state comprised of skyrmions, helicies, [26,27], and/or labyrinth domains (Fig. S1c), all of which possess a regular periodicity determined by the average A and D, but not a longrange orientation.…”