Several cobalt-based Heusler alloys have been predicted to exhibit Weyl Semimetal behavior due to time reversal symmetry breaking. Co 2 TiGe is one of the predicted ferromagnetic Weyl semimetals. In this work, we report weak localization and small anomalous Hall conductivity in half-metallic Co 2 TiGe thin films grown by molecular beam epitaxy. The longitudinal resistivity shows semimetallic behavior. Elaborate analysis of longitudinal magnetoconductance shows the presence of a weak localization quantum correction present even up to room temperature and reduction in dephasing length at lower temperature. Negative longitudinal magnetoresistance is observed from 5 to 300 K, but at 300 K magnetoresistance becomes positive above 0.5 T magnetic field. The anomalous Hall effect has been investigated in these thin films. The measured anomalous Hall conductivity decreases with increasing temperature, and a small anomalous Hall conductivity has been measured at various temperatures which may be arising due to both intrinsic and extrinsic mechanisms.

Thin films of the high Curie temperature intermetallic ferromagnet β-Fe2Si were synthesized via molecular beam epitaxy. Investigation using X-ray diffraction and atomic force microscopy shows a hexagonal crystal structure and a smooth topography. Theoretically, Fe2Si has been predicted to exhibit uniquely desirable magnetotransport properties. We report on these properties experimentally, including the ordinary Hall coefficient R0 and anomalous Hall resistivity ρxyAH. The compound is found to be a soft Heisenberg ferromagnet with temperature dependent magnetization based on the thermal excitation of spin waves. We present a detailed look into the contributions to its longitudinal resistivity, which due to the presence of a spin-flip gap ΔkB, indicating a half-metallic band structure. The correct scaling relations between these components of the resistivity tensor (ρxx and ρxy) are also discussed.

Here, the authors report a detailed method of growing LaAlGe, a nonmagnetic Weyl semimetal, thin film on silicon(100) substrates by molecular beam epitaxy and their structural and electrical characterizations. About 50-nm-thick LaAlGe films were deposited and annealed for 16 h in situ at a temperature of 793 K. As-grown high-quality films showed uniform surface topography and near ideal stoichiometry with a body-centered tetragonal crystal structure. Temperature-dependent longitudinal resistivity can be understood with dominant interband s-d electron-phonon scattering in the temperature range of 5-40 K. Hall measurements confirmed the semimetallic nature of the films with an electron-dominated charge carrier density of ∼7.15 × 10 21 cm −3 at 5 K.

Many transition metal dichalcogenides have been predicted and verified experimentally to exhibit topological semimetallic behavior due to symmetry breaking. NiTe2 is predicted to belong to an interesting class of materials: type-II topological semimetal. Here, we report the growth, structural, and magnetic properties of polycrystalline NiTe2 nanostructures synthesized using a two-step solvothermal technique. Nanostructures of NiTe2 crystalize in a hexagonal CdI2-type structure (space group P3¯m1) with lattice parameters a = b = 3.85 Å and c = 5.26 Å. NiTe2 nanostructures exhibit paramagnetic behavior at room temperature and display a large increase in magnetization below 30 K. These results will certainly pave the way to fully understand one- and two-dimensional NiTe2 for topological behavior that can be useful for novel device applications.

The authors have successfully grown Fe2CrAl nanowires on polished Si/SiO2 substrates using the electrospinning method. The diameter of nanowires varies from 50 to 300 nm. These nanowires exhibit a cubic crystal structure with lattice disorder. The nanowires are ferromagnetic with a Curie temperature greater than 400 K, much higher than that the bulk reported value. This higher Curie temperature is attributable to disordering in lattice sites, which causes an enhanced exchange interaction between pairs of iron atoms.

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Thin films of ferromagnet Fe2Ge were grown via molecular beam epitaxy, and their electrical and magneto-transport properties were measured for the first time. X-ray diffraction and vibrating sample magnetometry measurements confirmed the crystalline ferromagnetic Fe2Ge phase. The observed high-temperature maximum in the longitudinal resistivity, as well as the observed suppression of electron–magnon scattering at low temperatures, points to the presence of strong spin polarization in this material. Measurements of the Hall resistivity, ρxy, show contributions from both the ordinary Hall effect and the anomalous Hall effect, ρxyAH, from which we determined the charge carrier concentration and mobility. Measurements also show a small negative magnetoresistance in both the longitudinal and transverse geometries. Fe2Ge holds promise as a useful spintronic material, especially for its semiconductor compatibility.

Theoretical calculations and experimental observations show MoTe 2 is a type II Weyl semimetal, along with many members of transition metal dichalcogenides family. We have grown highly crystalline large-area MoTe 2 thin films on Si/SiO 2 substrates by chemical vapor deposition. Very uniform, continuous, and smooth films were obtained as confirmed by scanning electron microscopy and atomic force microscopy analyses. Measurements of the temperature dependence of longitudinal resistivity and current-voltage characteristics at different temperature are discussed. Unsaturated, positive quadratic magnetoresistance of the as-grown thin films has been observed from 10 K to 200 K. Hall resistivity measurements confirm the majority charge carriers are hole.