ABNORMAL MAGNETIC TRANSPORT IN CO MN/CO SANDWICHES/

A series of Co/Mn/Co sandwiches was prepared on GaAs(001) surfaces at room temperature via a molecular beam epitaxy (MBE) technique. Reflect ion high-energy electron diffraction (RHEED) and x-ray-diffraction (XR D) analysis indicated a polycrystalline structure. By standard magneto resistance measurements, it was found that with a Mn spacer thickness of 8 Angstrom, a seldom-seen positive magnetoresistance (PMR) as high as 16% was exhibited at room temperature. The measurement under differ ent geometries of H and I indicated that it was not an anisotropic mag netoresistance (AMR) effect. The MR-H curve displayed no hysteresis in contrast to the magnetometry measurement: An interface effect is prop osed as a possible origin of this phenomenon. (C) 1997 American Instit ute of Physics.