Magnetoresistance and spin-transfer torque effects in soft CoSiBFeNb magnets

Abstract Magnetotransport properties of ultra-soft magnets were studied on both macroscopic and microscopic scales by performing bulk and point-contact measurements, respectively, in CoSiBFeNb ribbons prepared by melt spinning technique. While the bulk measurements did not show any variations in dc resistance as a function of applied magnetic field (zero magnetoresistance), the point-contact measurements revealed giant-magnetoresistance-like changes in the resistance of small volumes (106–109 nm3) associated with the contacts. A high-density current applied to the contacts was found to affect the point-contact magnetoresistance – the magnetic field where resistive switching occurs was found to shift with the applied dc bias. The magnetotransport effects observed on the microscopic scale could be attributed to specific local configurations of magnetic domains in CoSiBFeNb and effects of spin-transfer torque on the domain configurations.