Browsing by Author "Schnelle, Walter"

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Intermediate-Valence Ytterbium Compound Yb4Ga24Pt9: Synthesis, Crystal Structure, and Physical Properties
(2017-08-07)
Sichevych, Olga
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Prots, Yurii
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Utsumi, Yuki
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Akselrud, Lev
;
Schmidt, Marcus
The title compound was synthesized by a reaction of the elemental educts in a corundum crucible at 1200 degrees C under an Ar atmosphere. The excess of Ga used in the initial mixture served as a flux for the subsequent crystal growth at 600 degrees C. The crystal structure of Yb4Ga24Pt9 was determined from single-crystal X-ray diffraction data: new prototype of crystal structure, space group C2/m, Pearson symbol mS74, a = 7.4809(1) angstrom, b = 12.9546(2) angstrom, c = 13.2479(2) angstrom, beta = 100.879(1)degrees, V = 1260.82(6) angstrom(3), R-F = 0.039 for 1781 observed reflections and 107 variable parameters. The structure is described as an ABABB stacking of two slabs with trigonal symmetry and compositions Yb4Ga6 (A) and Ga12Pt6 (B). The hard. X-ray photoelectron spectrum (HAXPES) of Yb4Ga24Pt9 shows both Yb2+ and Yb3+ contributions as evidence of an intermediate valence state of ytterbium The evaluated Yb valence of similar to 2.5 is in good agreement with the results obtained from the magnetic susceptibility measurements. The compound is, a bad metallic conductor.
Thickness dependence of the anomalous Hall effect in thin films of the topological semimetal Co2MnGa
(2019-08-19)
Markou, Anastasios
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Kriegner, Dominik
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Gayles, Jacob
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Zhang, Liguo
;
Chen, Yi-Cheng
Topological magnetic semimetals promise large Berry curvature through the distribution of the topological Weyl nodes or nodal lines and further novel physics with exotic transport phenomena. We present a systematic study of the structural and magnetotransport properties of Co2MnGa films from thin (20 nm) to bulklike behavior (80 nm) in order to understand the underlying mechanisms and the role of topology. The magnetron sputtered Co2MnGa films are L2(1)-ordered showing very good heteroepitaxy and a strain-induced tetragonal distortion. The anomalous Hall conductivity was found to be maximum at a value of 1138 S/cm, with a corresponding anomalous Hall angle of 13%, which is comparatively larger than topologically trivial metals. There is good agreement between the theoretical calculations and the Hall conductivity observed for the 80 nm film, which suggests that the effect is intrinsic. Thus, the Co2MnGa compound manifests as a promising material for topologically driven spintronic applications.