Rare-earth delafossites were recently proposed as promising candidates for the realization of an effective S = 1/2 quantum spin liquid (QSL) on the triangular lattice. In contrast to the most actively studied triangular-lattice antiferromagnet YbMgGaO4, which is known for considerable structural disorder due to site intermixing, NaYbS2 delafossite realizes structurally ideal triangular layers. We present detailed µSR studies on this regular (undistorted) triangular Yb sublattice based system with effective spin J eff = 1/2 in the temperature range 0.05 -40 K. Zero-field (ZF) and longitudinal field (LF) µSR studies confirm the absence of any long range magnetic order state down to 0.05 K (∼ J/80). Current µSR results together with the so far available bulk characterization data suggest that NaYbS2 is an ideal candidate to identify QSL ground state.

Recently, several putative quantum spin liquid (QSL) states were discovered in {\tilde S} = 1/2S̃=1/2 rare-earth based triangular-lattice antiferromagnets (TLAF) with the delafossite structure. In order to elucidate the conditions for a QSL to arise, we report here the discovery of a long-range magnetic order in the Ce-based TLAF KCeS_22 below T_{\mathrm N} = 0.38TN=0.38 K, despite the same delafossite structure. Finally, combining various experimental and computational methods, we characterize the crystal electric field scheme, the magnetic anisotropy and the magnetic ground state of KCeS_22.

Nb3Ge films with thicknesses between 60 and 800 nm were deposited onto heated sapphire substrates by thermal coevaporation. Stoichiometric Nb3Ge samples crystallize in a single-phase A 15 structure with a lattice parameter of 5.14 ~. Critical current densities and upper critical magnetic inductions were measured as a function of temperature, film thickness, and magnetic field orientation. The critical currents and fields show maxima for parallel field orientation. This is due to the random orientation of the crystallites. With decreasing thickness an increasing second maximum for normal field orientation is observed. This behavior can be explained by additional precipitates caused by internal stress.

Analysis of Binary Compound Thin Films with the Electron Microprobe Two methods for the quantitative analysis of binary compound thin films by electron micro-probe have been developed and applied on some compounds with A 15-structure. Appropriate calibration curves for these compounds are given and compared with results of three theoretical or semiempirical methods showing fairly good agreement.

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