Experimental indications for a critical relaxation time in spin-glasses

Long-time (5-${10}^4$ sec) superconducting-quantum-interference-device magnetometry measurements on a Au-8 at.% Fe spin-glass imply the existence of a well-defined characteristic time, beyond which no additional change of magnitude or position of the susceptibility cusp occurs. This characteristic time is 5 × ${10}^2$ sec at an applied field of 0.1 mT (1 G) and estimated to be ${10}^5$ sec at zero field. It is inferred that this characteristic time is coupled to a critical value of the cluster relaxation times where intercluster coupling becomes strong enough to initiate cluster recombinations.