Antiferromagnetic dipolar ordering in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow><mml:mo>[</mml:mo><mml:msub><mml:mi mathvariant="normal">Co</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi mathvariant="normal">Mn</mml:mi><mml:mi mathvariant="normal">Ge</mml:mi><mml:mo>∕</mml:mo><mml:mi mathvariant="normal">V</mml:mi><mml:mo>]</mml:mo></mml:mrow><mml:mi>N</mml:mi></mml:msub></mml:math>multilayers

Solid State Communications

et al. 2007

Half-metallic ferromagnetic full-Heusler alloys containing Co and Mn, having the formula Co2MnZ where Z a sp element, are among the most studied Heusler alloys due to their stable ferromagnetism and the high Curie temperatures which they present. Using state-of-the-art electronic structure calculations we show that when Mn atoms migrate to sites occupied in the perfect alloys by Co, these Mn atoms have spin moments antiparallel to the other transition metal atoms. The ferrimagnetic compounds, which result from this procedure, keep the half-metallic character of the parent compounds and the large exchange-splitting of the Mn impurities atoms only marginally affects the width of the gap in the minority-spin band. The case of [Co1−xMnx]2MnSi is of particular interest since Mn3Si is known to crystallize in the Heusler L21 lattice structure of Co2MnZ compounds. Robust half-metallic ferrimagnets are highly desirable for realistic applications since they lead to smaller energy losses due to the lower external magnetic fields created with respect to their ferromagnetic counterparts.

Section: Introductionmentioning

confidence: 99%

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

Solid State Communications

et al. 2007

“…The most successful recent applications in spintronics concern the half-metallic full Heusler alloys. The group of Westerholt has incorporated Co 2 MnGe in the case of spin-valves and multilayer structures [9]. The group of Reiss managed to create magnetic tunnel junctions based on Co 2 MnSi [10,11].…”

Section: Half-metallic Heusler Alloysmentioning

confidence: 99%

Spin-polarization and electronic properties of half-metallic Heusler alloys calculated from first principles

J. Phys.: Condens. Matter

Mavropoulos

2007

170

Abstract. Half-metallic Heusler alloys are amongst the most promising materials for future magnetoelectronic applications. We review some recent results on the electronic properties of these compounds. The origin of the gap in these half-metallic alloys and its connection to the magnetic properties are well understood. Changing the lattice parameter shifts slightly the Fermi level. Spinorbit coupling induces states within the gap but the alloys keep a very high degree of spin-polarization at the Fermi level. Small degrees of doping and disorder as well as defects with low formation energy have little effect on the properties of the gap, while temperature effects can lead to a quick loss of half-metallicity. Finally we discuss two special issues; the case of quaternary Heusler alloys and the half-metallic ferrimagnets.

“…The group of Westerholt has extensively studied the properties of Co 2 MnGe films and they have incorporated this alloy in the case of spinvalves and multilayer structures. 5 The group of Reiss managed to create magnetic tunnel junctions based on Co 2 MnSi. 6 A similar study of Sakuraba and collaborators resulted in the fabrication of magnetic tunnel junctions using Co 2 MnSi as one magnetic electrode and Al-O as the barrier (Co 75 Fe 25 is the other magnetic electrode) and their results are consistent with the presence of half-metallicity for Co 2 MnSi.…”

mentioning

confidence: 99%

Effect of doping and disorder on the half metallicity of full Heusler alloys

Applied Physics Letters

Özdoğan

Aktaş

et al. 2006

Heusler alloys containing Co and Mn are amongst the most heavily studied half-metallic ferromagnets for future applications in spintronics. Using state-of-the-art electronic structure calculations, we investigate the effect of doping and disorder on their electronic and magnetic properties. Small degrees of doping by substituting Fe or Cr for Mn scarcely affect the half-metallicity. A similar effect is also achieved by mixing the sublattices occupied by the Mn and sp atoms. Thus the half-metallicity is a robust property of these alloys.PACS numbers: 75.47. Np, 75.50.Cc, 75.30.Et The intensive development of electronics based on the combination of magnetic and semiconducting materials has brought in the center of scientific research new exotic materials. Half-metallic ferromagnets, which were first predicted by de Groot and collaborators in 1983, 1 have the peculiarity that the band-structure of the minorityspin electrons is semiconducting while of the majorityspin electrons is a normal metallic one. Such materials could maximize the efficiency of spintronic devices.2 Several Heusler compounds like NiMnSb and Co 2 MnSi have been predicted to be half-metals. 3Ishida and collaborators were, to the best of our knowledge, the first to study by means of ab-initio calculations the full-Heusler compounds of the type Co 2 MnZ, where Z stands for Si and Ge, and have shown that they are half-metals.4 Later the origin of half-metallicity in these compounds has been largely explained.3 Many experimental groups during the last years have worked on these compounds and have tried to synthesize them mainly in the form of thin films and incorporate them in spintronic devices. The group of Westerholt has extensively studied the properties of Co 2 MnGe films and they have incorporated this alloy in the case of spinvalves and multilayer structures.5 The group of Reiss managed to create magnetic tunnel junctions based on Co 2 MnSi.6 A similar study of Sakuraba and collaborators resulted in the fabrication of magnetic tunnel junctions using Co 2 MnSi as one magnetic electrode and Al-O as the barrier (Co 75 Fe 25 is the other magnetic electrode) and their results are consistent with the presence of half-metallicity for Co 2 MnSi.7 Dong and collaborators recently managed to inject spin-polarized current from Co 2 MnGe into a semiconducting structure.8 Finally Kallmayer et al. studied the effect of substituting Fe for Mn in Co 2 MnSi films and have shown that the experimental extracted magnetic spin moments are compatible with the half-metallicity for small degrees of doping.