Diamagnetism and muon Knight shift in semiconducting Bi1−x Sb x single crystals

The Knight shift of positive muons (⁺) implanted in semiconducting single crystals of Bi_1–x Sb _x (x=0.085, 0.14, 0.19) has been measured as a function of temperature and sample orientation. The Knight shift (KS) is generally negative and is found to scale with the negative total macroscopic susceptibility; the scaling is independent ofx but dependent on the orientation. One concludes that only the valence and conduction bands near theL-symmetry point in the Brillouin zone contribute to the ⁺ Knight shift, most likely by the contact hyperfine interaction. Furthermore the valence bands and the conduction bands seem to be associated with the same hyperfine coupling constants. These conclusions are quite unexpected and call for a new theoretical approach.     

μSR measurements on UAl2

Magnetic properties and crystallization of amorphous Fe₇₄Co₁₀B₁₆ have been investigated by Mössbauer and DSC measurements. Probability distribution of hyperfine field P(H) shows a single peak which shifts to lower fields with increase in temperature. Crystallization has been found to give rise to α-(Fe-Co), Fe₂B and (Fe-Co)₂B phases.     

μ+‐site in heavy‐fermion compounds

We report on the μ⁺‐site determination in different heavy‐fermion systems, resulting from the analysis of the angular dependence of parameters of the μSR spectra. After an introduction on the basics of the analysis of the μ⁺‐Knight shift, we briefly discuss the specific information accessible once the knowledge of the crystallographic site occupied by the implanted muon is gained. This revised version was published online in July 2006 with corrections to the Cover Date.     

Muon Knight shift in platinum and in β-PdHx (x=0.70, 0.75)

The ⁺ Knight shift in platinum has been measured between 20 K and 785 K. It shows a strong temperature dependence and scales with the magnetic bulk susceptibility. A temperature independent contribution of +40 to +60 ppm and a d-electron induced hyperfine field per unpaired d-electron per atom ofB _hf,d =–5.03 kG (±8.5%) are obtained. The ⁺ Knight shift in PdH_0.70 and PdH_0.75 shows no dependence on temperature between 20 K andRT and increases fromK ppm forx=0.70 toK ppm forx=0.75, in good agreement with proton Knight shift measurements.     

Identification ofμ +-sites in the 1-2-3 compoundin the 1-2-3 compound

Possibleμ ⁺ sites have been identified by a comparison of measured spontaneous internal fields in YBa₂Cu₃O_6+δ and REBa₂Cu₃O_7−δ and of measured second moments and width of transverse field powder spectra with the corresponding calculated quantities. In the YBa₂Cu₃O₇ system only one possibleμ ⁺ site emerges at a distance of ∼1.05 A from a chain oxygen O(4) at the position (0.15(1), 0.44(1), 0.071(1)). In the system YBa₂Cu₃O₆ the only possibleμ ⁺ sites are near to an oxygen O(1) with z/c=0.133 and the same distance as above. The analysis leads also to improved valuesμ _Ho = 2.2(1)μ _B andμ _Cu = 0.67(4)μ _B and to a determination of the latters direction:μ _Cu ‖〈110〉.     

Funktionen,deren Logarithmus darstellbar ist als Differenz subharmonischer Funktionen

Ohne Zusammenfassung Dieser Artikel ist ein Auszug der Dissertation des Verfassers.