Low field magnetoresistance of intergranular tunneling in field-aligned chromium dioxide powders

Abstract

The magnetic and magnetotransport properties of field-aligned single domain half-metallic CrO2 powders have been studied. Needle-shaped nanoparticles of CrO2 have been aligned in a strong magnetic field. The aligned powder sample shows a strong anisotropy along the alignment direction. The conduction mechanism of the aligned CrO2 powder sample has been examined and is consistent with the intergranular spin dependent tunneling. Negative tunneling magnetoresistance (TMR) of about 41% is achieved in a small field in the vicinity of the coercive field at 5 K. The magnetoresistance (MR) versus field curve shows two well-separated narrow peaks at the coercive fields and resembles that of a magnetic tunnel junction. This junction-like MR results from the narrow switching field distribution of the aligned powders. The results suggest that the aligned magnetic CrO2 particles may find novel applications in spin transport structures and devices.

Dependencies are inferred from the claim text.