Heusler alloy Ni2MnIn
The intermetallic ternary compound Ni2MnIn is a Heusler alloy, named after F. Heusler1), who first described ferromagnetic manganese alloys in 1903 . Eigthy years later R.A. de Groot2) discovered that some of these alloys belong to a new class of magnetic materials which he called "half-magnetic ferromagnets". These materials share simultaneously the property of a semiconductor for the spin up electrons and the property of a normal metal for the spin down electrons. Calculations of the density of states show an energy gap between the valence and conduction bands for the minority-spin electrons and a continuous band for the majority electrons.
Fig. 1: Density of states calculated by K.A. Kilian et al.3).
Ni2MnIn seems to be promising as spin polarized electrode
on InAs (001), becausse there is no Shottky barrier and virtually no lattice
The Ni2MnIn layers are grown by coevaporating the three compounds nickel, manganese and indium. The electron beam evaporator contains three independent, flux-controlled crucibles. As substrates we use InAs (001), silicon and thin carbon films which are heated during deposition. The layers on InAs and silicon substrates are structured by a lift-off process for further characterization of their electrical and magnetic properties.
The Ni2MnIn films on InAs and silicon substrate are analyzed in a scanning electron microscope (SEM), the layers on thin carbon films in a transmission electron microscope (TEM). In both electron microscopes we do energy dispersive analysis of X-rays in order to check the stoichometry. In addition, we gain information about the lattice constant by electron diffraction in the TEM. Film thickness and magnetization are measured by atomic force microscope (AFM) and magnetic force microscope (MFM), respectively.
Fig. 3: AFM image of a 50 nm thick film. Electron diffraction pattern.
1) F. Heusler, Verh. Dtsch. Ges. 5, 219 (1903)
Last modified: 17/07/2002