Band-structure calculations of the half-metallic ferromagnetism and structural stability of full- and half-Heusler phases

J. Phys.: Condens. Matter

Bihlmayer

Blügel

2005

Structural and magnetic properties of the (001) and (111) Abstract. Using the full potential linearised augmented planewave method we study the electronic and magnetic properties of the (001) and (111) surfaces of the half-metallic Heusler alloy NiMnSb from first-principles. We take into account all possible surface terminations including relaxations of these surfaces. Special attention is paid to the spin-polarization at the Fermi level which governs the spin-injection from such a metal into a semiconductor. In general, these surfaces lose the half-metallic character of the bulk NiMnSb, but for the (111) surfaces this loss is more pronounced. Although structural optimization does not change these features qualitatively, specifically for the (111) surfaces relaxations can compensate much of the spin-polarization at the Fermi surface that has been lost upon formation of the surface.

Section: Introductionsupporting

confidence: 75%

Structural and magnetic properties of the (001) and (111) surfaces of the half-metal NiMnSb

J. Phys.: Condens. Matter

Bihlmayer

Blügel

2005

“…Block and collaborators have studied the effect of tetragonalization on the properties of both NiMnSb and Co 2 CrAl [33]. They found that although tetragonalization largely affected the shape and width of the gap, the systems remained half-metallic for moderate degrees of strain.…”

Section: Effect Of the Lattice Parametermentioning

confidence: 99%

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

J. Phys.: Condens. Matter

Mavropoulos

2007

174

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.

“…22 Except interfaces states, temperature driven excitations [23][24][25] and defects 26 also seem to destroy halfmetallicity. Also some other important aspects of these alloys a͒ Electronic mail: kozdogan@gyte.edu.tr b͒ like the orbital magnetism, 27 the structural stability, 28 and the interplay of exchange interactions 29,30 have been addressed in the literature.…”

Section: Introductionmentioning

confidence: 99%

Influence of mixing the low-valent transition metal atoms (Y, Y=Cr, Mn, Fe) on the properties of the quaternary Co2[Y1−xYx]Z (Z=Al, Ga, Si, Ge, or Sn) Heusler compounds

Özdoğan

Aktaş

Journal of Applied Physics

et al. 2007

We complement our study on the doping and disorder in Co2MnZ compounds [I. Galanakis et al., Appl. Phys. Lett. 89, 042502 (2006) and K. Özdogan et al., Phys. Rev. B 74, (2006)] to cover also the quaterarny Co2[Y1−xY *x ]Z compounds with the lower-valent transition metals Y,Y * being Cr, Mn or Fe and the sp atom Z being one of Al, Ga, Si, Ge, Sn. This study gives a global overview of the magnetic and electronic properties of these compounds since we vary both Y and Z elements. Our results suggest that for realistic applications the most appropriate compounds are the ones belonging to the families Co2[Mn1−xCrx]Z with x > 0.5 irrespectively of the nature of the sp atoms since they combine high values of majority DOS at the Fermi level due to the presence of Cr, and half-metallicity with large band-gaps. On the other hand the presence of Fe lowers considerably the majority density of states at the Fermi level and when combined with an element belonging to the Si-column, it even can destroy half-metallicity.