Abstract We report a clear manifestation of the negative contribution to the magnetoresistance due to domain walls in Co 2 MnGe-Heusler submicron zigzag wires in which the domain structure, domain size and domain wall density can be well controlled. The magnetic behavior of these systems results from the interplay between the intrinsic magneto-crystalline ( K 4 ) anisotropy, growth induced uniaxial ( K U = 4.7x10 3 J/m 3 ) anisotropy and shape anisotropy ( K S ), as observed by magnetic-force microscopy (MFM) and longitudinal Kerr hysteresis loop measurements. Magnetoresistance measurements were performed by the four-point method under a field applied in the plane of the wires at a temperature of 300 K. In these structures, domain wall-creation and annihilation occur in a coherent way. As a result, clear jumps of the resistance are detected during the transition from single-domain- to multi-domain states. At room temperature a value R DW = -2.5 mΩ was obtained; this result is the same order of magnitude as other experimental and theoretical findings. The negative resistive contribution due to the domain wall is also discussed and compared with the existing theoretical models.
Tópico:
Heusler alloys: electronic and magnetic properties