Half-Metallic Diluted Antiferromagnetic Semiconductors

Abstract

The possibility of half-metallic antiferromagnetism, a special case of ferrimagnetism with a compensated magnetization, in the diluted magnetic semiconductors is highlighted on the basis of the first principles electronic structure calculation. As typical examples, the electrical and magnetic properties of II-VI compound semiconductors doped with 3d transition metal ion pairs-(V, Co) and (Fe, Cr)-are discussed.PACS numbers: 71.55. Gs, 75.50.Pp Since the discovery of ferromagnetic diluted magnetic semiconductors (DMSs) [1,2,3], considerable attention has been paid to the origin and stability of their ferromagnetism [4,5,6,7,8,9]. One of the main issues has been how to realize the magnetic transition temperature that exceeds room temperature for these DMSs. This is partly due to the possible applications of such materials to spin-electronics [10]. Well-defined magnetization is certainly an indication of a new degree of freedom that can store and transfer information. However, attaining a sufficiently high magnetic transition temperature for such applications seems to be a difficult task currently [3,11,12,13,14]. Such a functionality that is expected for DMSs, however, is not restricted only to the ferromagnetic DMSs. In this Letter, we propose a new candidate for spin-electronics materials, namely, half-metallic diluted antiferromagnetic semiconductors. We expect that these materials will show significant spindependent electronic properties, and hence can be used as spin-electronics materials.The concept of half-metallic antiferromangets was first proposed by van Leuken and de Groot many years ago [15]. They pointed out that in a special case of ferrimagnetism it might be possible for a system to become half-metallic, i.e., metallic in one spin direction of electrons but insulated in the other spin direction. Obviously, this is impossible for usual antiferromagnets because of the spin-rotational symmetry, but it is not necessarily the case for ferrimagnets with a compensated magnetic moment. Van Leuken and de Groot referred to such cases as half-metallic antiferromagnetism. Later, Pickett pointed out on the basis of first-principles calculation that La 2 VCuO 6 , La 2 MnO 6 , and La 2 MnCoO 6 with a double-perovskite structure might be likely candidates for half metallic antiferromagnets [16]. However, thus far, the existence of such materials has not been verified experimentally. This indicates that intermetallic compounds or oxides may not be suitable candidates for half-metallic antiferromagnets. It could be possible that their magnetic and crystal structures are not as stable energetically as predicted by LDA (local density approximation) calculations.In contrast to the above cases where the band structure is hardly controlled by small modifications of the (a)

Electronic, magnetic and transport properties of rare-earth monopnictides

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Defects-driven appearance of half-metallic ferrimagnetism in Co–Mn-based Heusler alloys

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