NONHYSTERETIC M-H LOOPS IN AMORPHOUS RIBBONS CARRYING ALTERNATING CURRENTS

The perpendicular field H(p) generated by direct current J(d) usually shifts and narrows the M-H loops of amorphous ribbons bat cannot produ ce zero coercive field Hc because of enhanced pinning of domain walls at elevated The enhanced pinning inhomogeneity DELTAS (the difference in strength of pinning close to the opposite faces of the ribbon) can however be used in order to obtain zero H(c) by means of an alternatin g current or current pulses. When H(p) has nonvanishing projections P on the magnetizations of domains responsible for H(c), H(c)=0 occurs f or P=S(u) (S(u) is the strength of; the weakest pinning centers associ ated with H(c)) at zero applied field H. Since DELTAS can be simply co ntrolled (e.g. by applying stress on magnetostrictive alloys) zero H(c ) can be obtained for almost any material over sizable range of freque ncies and amplitudes of H. Some examples are given in the paper.