Surface properties of the half-and full-Heusler alloys

Abstract

Abstract. Using a full-potential ab-initio technique I study the electronic and magnetic properties of the (001) surfaces of the half-Heusler alloys, NiMnSb, CoMnSb and PtMnSb and of the full-Heusler alloys Co 2 MnGe, Co 2 MnSi and Co 2 CrAl. The MnSb terminated surfaces of the half-Heusler compounds present properties similar to the bulk compounds and, although the half-metallicity is lost, an important spinpolarisation at the Fermi level. In contrast to this the Ni terminated surface shows an almost zero net spin-polarisation. While the bulk Co 2 MnGe and Co 2 MnSi are almost half-ferromagnetic, their surfaces lose the half-metallic character and the net spin-polarisation at the Fermi level is close to zero. Contrary to these compounds the CrAl terminated (001) surface of Co 2 CrAl shows a spin polarisation of about 84%.

Epitaxial growth of Co2Cr0.6Fe0.4Al Heusler alloy thin films on MgO (0 0 1) substrates by magnetron

“…Cobalt-based full-Heusler alloys have been considered potential candidates for showing HMF properties. Their structural and magnetic properties have been intensively investigated experimentally [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and theoretically [19][20][21][22][23] because they have comparatively high Curie temperatures T C . In particular, Co 2 Cr 1−x Fe x Al (CCFA) is expected to have suitable electro-magnetic properties for injecting a spinpolarized current [16,22].…”

Antiferromagnetic dipolar ordering in[Co2MnGe∕V]Nmultilayers

“…However, irrespective of the experimental method applied to determine the degree of spin polarization quantitatively, it is always definitely less than 100%. The main reason, which has been suggested for this reduction, is site disorder in the film and at the interfaces, since only the perfectly ordered Heusler alloy exhibits a gap in the minority spin band [15,16]. Interfaces in thin film heterostructures combining the Heusler alloys with other materials are of utmost importance for spintronic devices, since the spin polarization has to be stable down to the first few monolayers of the interface.…”

“…Interfaces in thin film heterostructures combining the Heusler alloys with other materials are of utmost importance for spintronic devices, since the spin polarization has to be stable down to the first few monolayers of the interface. However, these compounds are prone to interdiffusion and site disorder, which both have the tendency to suppress the full spin polarization [15,16].…”

Ferrimagnetism and antiferro‐ magnetism in half‐metallic Heusler alloys

“…One of the most important features of these alloys is the Slater-Pauling behavior of their total spin magnetic moment which is given simply as a function of the number of valence electrons in the unit cell [5,6]. Authors have studied in the recent years several aspects of these half-metallic alloys like the properties of surfaces [7,8,9] and interfaces with semiconductors [10,11], the quaternary [12,13], the orbital magnetism [14,15], the effect of doping and disorder [16,17], the exchange constants [18] and the magneto-optical properties [19].Half-metallic ferrimagnetic Heusler alloys like Mn 2 VAl, where Mn and V atoms have antiparallel spin moments, are of particular interest since they create smaller external magnetic fields and thus lead to smaller energy losses [20,21]. In the extreme case like Cr 2 MnSb (alloys with 24 valence electrons) Cr and Mn spin moments cancel each other and the compounds are named as fully-compensated half-metallic ferrimagnets or simply half-metallic antiferromagnets [22].…”

“…One of the most important features of these alloys is the Slater-Pauling behavior of their total spin magnetic moment which is given simply as a function of the number of valence electrons in the unit cell [5,6]. Authors have studied in the recent years several aspects of these half-metallic alloys like the properties of surfaces [7,8,9] and interfaces with semiconductors [10,11], the quaternary [12,13], the orbital magnetism [14,15], the effect of doping and disorder [16,17], the exchange constants [18] and the magneto-optical properties [19].…”