Fang Rui-Yi

New permanent magnetic MnBiDy alloy films

We have studied the magnetic properties of MnBiDy films fabricated by the thermal coevaporation method and annealed subsequently in a vacuum oven at temperatures of 350 °C–425 °C. The thicknesses of these films are in the range from 60 to 1200 nm. X‐ray diffraction analyses have confirmed that those samples have an hcp structure. Magnetic measurements revealed that the saturation magnetization σs=46–78 emu/g, remanence ratio R=0.67–0.98, coercive force μHc=2.2–7.3 kOe, and magnetic energy product (BH)m=3.3–14.3 MGOe. These values are sensitive to the film thicknesses. It was found that μHc reaches a maximum at d≊400 nm.

THE PROPERTIES OF MAGNETO-OPTICAL MNBIR (R=IN, GE, AND SN) THIN FILMS

The crystal structures and the magneto‐optical properties of MnBiR (R=Ge, In, and Sn) thin films are reported. We found that doping MnBi films with Ge enhances their Kerr rotation angle θk(θk=2.1°, at λ=633 nm). It is thus possible to consider MnBi film doped with Ge a good candidate of magneto‐optical recording material. In contrast, MnBi films doped with In or Sn loose the original NiAs‐type hcp structure and correspondingly the Kerr rotation angle θk, is decreased.

Study an magnetoresistance and stability for [Py/Cu/Co/Cu]/sub N/ spin valve multilayered films

The spin valve [NiFe/Cu/Co/Cu] multilayers were prepared by using electron beam method. The influences of the thickness of magnetic and non-magnetic layers preparation process on the magnetoresistance (MR) were studied. We also investigated the stability of MR and how to reduce the center field Ho, which is the center magnetic field of the linear region in the MR-H curve. Using fairly optimum preparing technology, we have deposited many samples with low center field Ho in the range 10-20 Oe, the MR merit is larger than 0.2%/Oe. The variation of the MR in this linear region is reversible during repeatedly magnetizing. The change of MR is smaller than 1% for several samples after aging one year in a dry air chamber and room temperature.

Large magneto-optical effect for MnBiRE thin films

Abstract It was found that the Kerr rotation angle θϰ is more than 2 degrees and the reflectivity R is in the range of 0.3–0.45 for MnBiRE (RE=Ce, Pr and Sm) thin films at the wavelength 6328Aand 20°C. The magnetic measurements showed that the magnetization is 20–40 emu/g. Hc=1–4 kOe, Tc=350−360°C and positive uniaxial perpendicular anisotropy is 106 erg/cm3. The microcrystalline grain size is within 20–40 nm.