Temporal and spatial separations between spin glass and short-range order

TL;DR

This study investigates the relationship between spin glass states and short- and long-range magnetic orders by tuning disorder in a spinel, revealing their coexistence and independence through neutron scattering and thermodynamic measurements.

Contribution

It introduces a controlled method to study the evolution from long-range to spin glass order, clarifying their relationship and independence in magnetic materials.

Findings

Correlation length inflection point matches heat capacity peak.

Spin glass freezing can occur above or below the temperature of spin order formation.

Short- and long-range order dynamics are unaffected by disorder.

Abstract

Broken-symmetry-induced order parameters account for many phenomena in condensed matter physics. For spin glasses, such a framework dictates its theoretical construction, whereas experiments have only established dynamical behaviors such as frequency dependent magnetic susceptibility and aging but not the thermodynamic phase. Experimental techniques have limitations when the spin glass is probed as an isolated state. To resolve this conundrum, we create an evolution from long-range order using a well-controlled tuning of the disorder on a spinel's sublattice. Cross-referencing a series of specimens at both long (milliseconds to seconds) and short (picosecond) time scales illustrates the relationship between spin glass and long- and short-range orders. The dynamics of short- and long-range order formations are not affected by disorder, as revealed by neutron magnetic diffuse scattering, however the ranges of these orderings are changed by the introduced disorder. Across all specimens, the inflection point of the correlation length's temperature dependence fully matches with the peak in heat capacity, while spin glass can freeze either below or well above this characteristic temperature of spin order formation. Our results identify an uncorrelated coexistence of the two and attribute components of the spin glass to individual spins at domain walls between spin clusters.