Experiments on Spin Glasses

Abstract

Static and dynamic scaling of the susceptibility of 3d spin glasses is found to yield consistent results and imply that there is a zero field phase transition at a finite temperature. On the other hand, dynamic scaling analysis of the in-field behaviour suggests that there is no phase transition in an applied magnetic field. The ageing phenomenon in spin glasses as observed in the response function and the field cooled magnetisation is discussed and a phenomenological picture for how it relates to the underlying spin configuration is derived.

Memory effect in electron glasses: Theoretical analysis via a percolation approach

“…Furthermore, after equilibration under fixed experimental conditions and subsequent moderate excitation during a time t w (e.g., by gate voltage 7 or electric field 9 ), the typical relaxation time of such films is found to scale with t w . This phenomenon, known as simple aging, is observed in many glassy systems such as polymers and supercooled liquids 29 , as well as spin glasses 30 .…”

Static Scaling on an Interacting Magnetic Nanoparticle System

“…From the analysis, the critical temperature T g 39 6 1 K and the critical exponents g 4.0 6 0.2 and b 1.2 6 0.1 were extracted. Corresponding values for short-range Ising and Heisenberg spin glasses fall in the range g 4.0 6 0.5 and b 0.6 6 0.1 [13,19,[21][22][23]. The larger value of b obtained for the magnetic nanoparticle system may indicate a system closer to its lower critical dimension since b is predicted to diverge at its lower critical dimension [24].…”

“…It could also be that a system with long-range dipole-dipole interaction is better compared with RKKY spin glasses. Unfortunately, there is a large diversity in the reported values for the critical exponents for metallic spin glasses which makes such a comparison unreliable [21].…”

Chaotic, memory, and cooling rate effects in spin glasses: Evaluation of the Edwards-Anderson model

“…1,2 Experimentally, this phenomenon is well documented through magnetization relaxation experiments and ac susceptibility measurements. [3][4][5] Despite the different experimental procedures needed for both type of measurements, magnetization relaxation and ac susceptibility give similar information regarding the aging behavior and its waiting time dependence.…”