Half-Metallic Ferromagnetism and Structural Stability of Zincblende Phases of the Transition-Metal Chalcogenides

Abstract

An accurate density-functional method is used to study systematically half-metallic ferromagnetism and stability of zincblende phases of 3d-transition-metal chalcogenides. The zincblende CrTe, CrSe, and VTe phases are found to be excellent half-metallic ferromagnets with large halfmetallic gaps (up to 0.88 eV). They are mechanically stable and approximately 0.31-0.53 eV per formula unit higher in total energy than the corresponding nickel-arsenide ground-state phases, and therefore would be grown epitaxially in the form of films and layers thick enough for spintronic applications.PACS numbers: 75.90.+w, 62.25.+g, 73.22.-f, 75.30.-m Phys Rev Lett 91, 037204 (2003) Half-metallic ferromagnets are seen as a key ingredient in future high performance spintronic devices, because they have only one electronic spin channel at the Fermi energy and, therefore, may show nearly 100 % spin polarization [1,2]. Since de Groot et al's discovery [3] in 1983, a lot of half-metallic ferromagnets have been theoretically predicted and some of them furthermore have been confirmed experimentally [4,5,6,7]. Much attention has been paid to understanding the mechanism behind the half-metallic magnetism and to studying its implication on various physical properties [8,9]. However, it is highly desirable to explore new halfmetallic ferromagnetic materials which are compatible with important III-V and II-VI semiconductors. For this purpose, effort has be made on the metastable zincblende (B3) phases such as the transition-metal pnictides [10,11,12,13,14,15,16,17,18,19,20]. Although zincblende phases of MnAs [11], CrAs [12,13] and CrSb [14] have been successfully fabricated as nanodots, ultrathin films and ultrathin layers in multilayers, it has not been possible to grow the zincblende half-metallic ferromagnetic phases as high-quality layers or thick films. This is due to the metastable zincblende phases being about 1 eV per formula unit higher in energy than the ground state nickel-arsenide (B8 1 ) phases. However, spintronic devices require thick films or layers. Therefore, it is important to explore theoretically other halfmetallic ferromagnetic materials, which on the one hand are compatible with the binary tetrahedral-coordinated semiconductors, and on the other hand are not only low in energy with respect to the corresponding ground-state structures but also mechanically stable against structural deformations.In this Letter we make use of an accurate fullpotential density-functional method to study systematically transition-metal chalcogenides in the zincblende and nickel-arsenide structures in order to find halfmetallic ferromagnetic phases which could be realized in the form of films and layers thick enough. We shall show that CrTe, CrSe, and VTe in the zincblende structure are excellent half-metallic ferromagnets with wide halfmetallic gaps. They will be proved to be mechanically stable and approximately 0.31-0.53 eV per formula unit higher in energy than the corresponding ground-state phases, and therefore would be grown epitax...

Prediction of half-metallic properties for the AMnSe2 (A=Rb, Cs) compounds from first-principle calculations

“…Besides half-and fullHeusler alloys, there are other families of materials which are halfmetallic systems, e.g., some metallic oxides like CrO 2 and Fe 3 O 4 , zinc-blende compounds like CrAs and CrSb and some manganite like La 0.7 Sr 0.3 MnO 3 [11][12][13][14][15][16][17][18]. An intensive scientific effort has been devoted to the investigation of the ternary manganese chalcogenides A-Mn-Q, where A ¼alkali metal and Q¼ chalcogenides [19][20][21][22][23][24][25].…”

Surface sp half-metallicity of zinc-blende calcium monocarbide

“…15 It was also found ZB CrAs has a high Curie temperature ͑above 400 K͒. 14 This work inspired many research groups to search for more HM ferromagnets with ZB structure, because this class of HM ferromagnets has higher Curie temperature, and their structure is compatible with conventional semiconductors, which make them most promising candidates for applications in spintronic devices.…”

“…14 This work inspired many research groups to search for more HM ferromagnets with ZB structure, because this class of HM ferromagnets has higher Curie temperature, and their structure is compatible with conventional semiconductors, which make them most promising candidates for applications in spintronic devices. So far, in addition to CrAs, many other binary ZB transition-metal pnictides, [15][16][17][18] chalcogenides, 15,18,19 and carbides 20,21 have been predicted to be HM from first-principles calculations, and some of them such as MnAs, CrSb, and CrTe have been realized in the form of thin films or multilayers. [22][23][24] The magnetic moments of HM ferromagnets with ZB structure mentioned above are mainly carried by the transition metals d electrons ͑we name them d HM ferromagnets͒.…”

Effect of (0001) Strain on the Electronic and Magnetic Properties of the Half-Metallic Ferromagnet Fe2Si

“…The valence band maximum is 0.164 eV at point S and the conduction band minimum is 0.682 eV at the BZ point L. Thus, Fe 2 Si forms a band gap of 0.518 eV in the vicinity of Fermi surface (spin-down). The half-metallic gap [14] is determined by the minimum difference between the lowest energy of the spin conductive bands with respect to the Fermi level and the absolute value of the highest energy of the spin valence bands. Therefore, the half-metallic gap of bulk Fe 2 Si is 0.164 eV.…”