Experimental observation of disorder-driven hysteresis-loop criticality.
We have studied the effect of magnetic disorder on the magnetization reversal process in thin Co/CoO films. The antiferromagnetic CoO layer allows a reversible tuning of the magnetic disorder by simple temperature variation. For temperatures above a critical temperature T(c), we observe a discontinuous magnetization reversal, whereas smooth magnetization loops occur for T<T(c). Our measurements establish the existence of a disorder-driven critical point in the nonequilibrium phase diagram. In addition, we observe scaling behavior in the vicinity of the critical point and determine the critical exponents beta = 0.022+/-0.006 and betadelta = 0.30+/-0.03 for this two-dimensional system.
Berger
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Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
Inomata
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A
Jiang
J S
JS
Pearson
J E
JE
Bader
S D
SD