Low Field Magnetoresistance at Room Temperature in CrO_2 Doped Polyvinyl Alcohol Films

摘要

Ferromagnetic CrO_2 nanoparticles embedded in a diamagnetic matrix of polyvinyl alcohol (PVA) presents an example of granular giant magnetoresistance (GMR) in a diluted magnetic composite structure. Usefully significant MR occurs at room temperature, viz. -6.8% in 3.0 wt% CrO_2-PVA, at field as small as 1.1 kOe. We suggest that the system is a natural analogue to dilute ferro-fluid structures composed of nanoscale magnetic particles in a viscous organic fluid (diamagnetic as well as an electrical insulator), i.e., this material displays a GMR effect without an introduction of chemical interfaces. It has great potential in various applications and can also facilitate studies of magnetotransport properties in GMR materials.