Comment on ‘‘Large magnetoresistance in an amorphous Co68.1Fe4.4Si12.5B15 ferromagnetic wire’’

Abstract
In a recent paper [Phys. Rev. B 47, 14 233 (1993)], Mandal and Ghatak claimed that a relative change in ac resistance up to 12% by changing the applied field was found in a Co-rich amorphous wire. This large change was ascribed to the giant magnetoresistance effect. We have made both dc and ac four-probe measurements on wires of the same composition under applied fields and no such large change has been observed. We believe that the results commented on reflect the strongly field-dependent self-inductance. Although the reactance at low frequencies is very small compared with the resistance, its effect could be enhanced under some circuit conditions.