Ferromagnet, half-metallic

Bands with 0 < < 1/2 or 3/2 band orbital, where N is the number of transition-metal atoms per unit volume if narrow enough for total removal of the spin de-... 

Heusler alloys have a rich variety of apphcations, owing to some of their unique properties. Some of these phases are half-metallic ferromagnets, exhibiting semiconductor properties for the majority-spin electrons and normal metallic behavior for the minority-spin electrons. Therefore, the conduction electrons are completely polarized. The Ni2MnGa phase is used as a magnetic shape memory alloy and single crystals of Cu2MnAl are used to produce monochromatic beams of polarized neutrons. 

Magnetic B-site ordered perovskites are of interest in at least two contexts, half-metallic ferromagnets , which show a large MR due to intergrain effects, and geometric magnetic... 

Sr2FeMo06- While this material has been known since 1963, intense interest was sparked by the announcement of room temperature MR in 1998. The material is ferro or ferrimagnetic with Tc > 400 K and a metallic conductor, Figure 35. This unusual combination of properties can be explained in terms of the half-metallic ferromagnetic electronic structure model. Figure 36. Note that the Fermi... 

Figure 36 Band stmcture calculations for Sr2FeMo06 showing half-metallic ferromagnetic character. (Reprinted with permission from T. Saitoh, M. Nakatake, A. Kakizaki, H. Nakajima, O. Morimoto, Sh. Xu,Y. Moritomo, N. Hamada, Y. Aiura, Phys.Rev., 2002, B66, 035112. 2002 by the American Physical Society)...

The structural similarity of MgAgAs-type compounds with Heusler alloys and with the transition-metal based half-metallic ferromagnets (de Groot et al. 1983) has provoked band-structure calculations of UNiSn (Mueller et al. 1987, Albers et al. 1987). Self-consistent-field scalar relativistic spin-polarized calculations neglecting the spin-orbit coupling revealed the following features of the valence band ... 

The authors argue that UNiSn endures an order-disorder lattice transition on annealing, and that the ordered lattice is a half-metallic ferromagnet , whereas the disordered component is non-magnetic. 

The Cr02 electronic structure was solved only in 1987 by Kamper et al. [63]. Cr02 is a half-metallic ferromagnet that is, it is a metal for the majority (spin up) electrons, but exhibits a semiconductor-type gap for the majority (spin down) electrons (Figure 19.4). This picture was confirmed by a spin-resolved photoemission from polycrystalline Cr02 films, which showed a spin polarization of almost 100% for... 

Mavropoulos Th, Galanakis 1 (2007) A review of the electronic and magnetic properties of tetrahedrally bonded half-metallic ferromagnets. J Phys Cond Matter 19 315221... 

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