IN15 High Resolution Spin-echo spectrometer

Spin glass dynamics

The glass transition, characterized by a dramatic slowing down of the dynamics without any noticeable change in the spatial order, is a generic phenomenon seen in systems as different as disordered magnets, polymers, and biological substances. In spite of its universality and of intense experimental and theoretical efforts it is still controversial whether the glass transition in structural glasses is a gradual freezing or a phase transition.
In this example, neutron spin echo (NSE) results reveal a pure power-law time decay of the spin autocorrelation function at the glass temperature Tg. This strict critical scaling behavior observed for spin glasses is also important for the vast family of glassy systems. Above the phase transition the strikingly non-exponential relaxation appears as an intrinsic, homogeneous feature of spin glasses.

Ref.: C. Pappas, F. Mezei, G. Ehlers, P. Manuel, I.A. Campbell - Physical Review B 68, 054431 (2003).