Experimental Verification of the ``Blocking Curve'' in Thin Permalloy Films

Abstract

An experimental verification of the theoretically predicted blocking curve in thin uniaxial ferromagnetic films is given. Hysteresis, associated with blocking, was investigated by means of a high-sensitivity torquemeter (rotational hysteresis). The blocking curve could be determined in two different ways: (i) by investigating the rotational hysteresis and (ii) by evaluating the structure constant S by means of transverse susceptibility measurements and calculating the blocking curve from the resulting value of S. Both results agree and show the existence of the blocking curve. It follows that the single-domain theory cannot be used to discuss critical effects such as magnetization switching.