IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Magnetic Interfaces and Nanostructures Thursday Sessions
       Session MI-ThP

Paper MI-ThP6
Epitaxial Growth of Ferromagnetic Ni@sub 2@MnIn Thin Films on InAs (001)

Thursday, November 1, 2001, 5:30 pm, Room 134/135

Session: Magnetic Thin Films & Surfaces Poster Session
Presenter: J.Q. Xie, University of Minnesota
Authors: J.Q. Xie, University of Minnesota
J.W. Dong, University of Minnesota
J. Lu, University of Minnesota
S. McKernan, University of Minnesota
C.J. Palmstrom, University of Minnesota
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There has been growing interest in ferromagnetic/semiconductor hererostructures for the development of spintronic devices which utilize the carrier's spin as well as its charge. InAs is the semiconductor of choice because of its high electron mobility and the ease to form an ohmic contact to it. Although no elemental ferromagnet is lattice matched to InAs, the lattice mismatch between the Heusler alloy Ni@sub 2@MnIn and InAs is only 0.2%. In bulk, Ni@sub 2@MnIn is reported to have a cubic (L2@sub 1@) crystal structure with a lattice constant a@sub 0@ = 6.069 Å and a Curie temperature ~ 314 K. Recent theoretical studies showed that the minority spins are situated at the @GAMMA@ point in Ni@sub 2@MnIn and the majority spins are far away from the @GAMMA@ point. Therefore, the band structure alignment between Ni@sub 2@MnIn and InAs would enhance the injection of the minority spins, suggesting that Ni@sub 2@MnIn may be a good choice for spin injection as a ferromagnetic contact. In this talk, we report on the epitaxial growth of Ni@sub 2@MnIn thin films on InAs (001) by the molecular beam epitaxy technique. Both in situ reflection high energy electron diffraction and ex situ x-ray diffraction, Rutherford backscattering spectrometry, and transmission electron microscopy measurements indicate the high-quality epitaxial growth of Ni@sub 2@MnIn films on InAs (001). The films have a Curie temperature ~ 170 K and a saturation magnetization ~ 420 emu/cm@super 3@. The lower Curie temperature, compared to that of bulk Ni@sub 2@MnIn, is believed to result from the growth of Ni@sub 2@MnIn in the B2 structure. Composition has a dramatic effect on the Curie temperature. For Ni@sub 2@MnIn@sub 1.7@, a Curie temperature of ~ 290 K was observed. If ordered films can be grown, significantly higher Curie temperatures may be expected.