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Biomedical subjects

R Orbach

Publications and source records attributed to R Orbach.

At least 19 recordsLinked to original sources
PubMed2006

End of aging in a complex system.

Aging phenomena in complex systems have been used as an important tool to investigate the physics of complexity. In particular, aging effects in spin glasses, measured using the thermoremanent magnetization decays, have been instrumental as a probe of complex equilibrium and nonequilibrium dynamics. In this Letter, we show that aging found in spin glass materials has a finite lifetime. After the aging part of the decay has ended, we find a post-aging decay which is apparently logarithmic in nature. This decay is independent of the waiting time and part of the same mechanism that produces aging.

Journal Article↗
PubMed2003

Full aging in spin glasses.

The discovery of dynamic memory effects in the magnetization decays of spin glasses in 1983 marked a turning point in the study of the highly disordered spin glass state. Detailed studies of the memory effects have led to much progress in understanding the qualitative features of the phase space. Even so, the exact nature of the magnetization decay functions has remained elusive, causing confusion. In this Letter, we report strong evidence that the thermoremanent magnetization decays scale with the waiting time t(w). By employing a series of cooling protocols, we demonstrate that the rate at which the sample is cooled to the measuring temperature plays a major role in the determination of scaling. As the effective cooling time t(eff)(c) decreases, t/t(w) scaling improves and for t(eff)(c)<20 s we find almost perfect t/t(w) scaling, i.e., full aging.

Journal Article↗