Formation of hydrogen impurity states in silicon and insulators at low implantation energies

The formation of hydrogen-like muonium (Mu) has been studied as a function of implantation energy in intrinsic Si, thin films of condensed van der Waals gases (N2, Ne, Ar, Xe), fused and crystalline quartz and sapphire. By varying the initial energy of positive muons (mu+) between 1 and 30 keV the number of electron-hole pairs generated in the ionization track of the mu+ can be tuned between a few and several thousand. The results show the strong suppression of the formation of those Mu states that depend on the availability of excess electrons. This indicates, that the role of H-impurity states in determining electric properties of semiconductors and insulators depends on the way how atomic H is introduced into the material.Comment: 4 pages, 4 enscapulated postscript figures, uses revtex4 twocolumn style to be published in Physical Review Letter

Direct observation of the oxygen isotope effect on the in-plane magnetic field penetration depth in optimally doped YBa2_2Cu3_3O7−δ_{7-\delta}

We report the first direct observation of the oxygen-isotope ($^{16}$O/$^{18}$O) effect on the in-plane penetration depth $\lambda_{ab}$ in a nearly optimally doped YBa$_2$Cu$_3$O$_{7-\delta}$ film using the novel low-energy muon-spin rotation technique. Spin polarized low energy muons are implanted in the film at a known depth $z$ beneath the surface and precess in the local magnetic field $B(z)$. This feature allows us to measure directly the profile $B(z)$ of the magnetic field inside the superconducting film in the Meissner state and to make a model independent determination of $\lambda_{ab}$. A substantial isotope shift $\Delta\lambda_{ab}/\lambda_{ab}=2.8(7)$% at 4 K is observed, implying that the in-plane effective supercarrier mass $m_{ab}^\ast$ is oxygen-isotope dependent with $\Delta m_{ab}^\ast/m_{ab}^\ast = 5.5(1.4)$.Comment: 4 pages, 2 figure

Pressure effects on the transition temperature and the magnetic field penetration depth in the pyrochlore superconductor RbOs_2O_6

We report magnetization measurements under high hydrostatic pressure in the newly discovered pyrochlore superconductor RbOs_2O_6 (T_c\simeq6.3K at p=0). A pronounced and {\it positive} pressure effect (PE) on T_c with dT_c/dp =0.090(1)K/kbar was observed, whereas no PE on the magnetic penetration depth \lambda was detected. The relative pressure shift of T_c [ dlnT_c/dp \simeq 1.5%/kbar] is comparable with the highest values obtained for highly underdoped high-temperature cuprate superconductors. Our results suggest that RbOs_2O_6 is an adiabatic BCS-type superconductor.Comment: 11 pages, 4 figure

Thin Film, Near-Surface and Multi-Layer Investigations by Low-Energy μ +SR

At the Paul Scherrer Institute (PSI, Villigen, Switzerland) the beam of low-energy positive polarised muons (LE-μ +) with tunable energy between 0.5 and 30keV allows the extension of the muon-spin-rotation technique (μSR) to studies on thin films and multi-layers (LE-μ +SR). The range of these muons in solids covers the near-surface region up to implantation depths of about 300nm. As a sensitive local magnetic probe with a complementary observational time window to other techniques LE-μ +SR offers the unique possibility to gain new insights in these nano-scale objects. After outlining the current status of the LE-μ + beam line we demonstrate the potential of this new technique by presenting the results of recent experiments: i) the direct observation of non-local effects in a superconducting Pb film, ii) the oxygen isotope effect on the in-plane penetration depth in optimally doped $${\text{YBa}}_{2} {\text{Cu}}_{3} {\text{O}}_{{7 - \delta }}$$ , and iii) the first observation of the conduction electron spin polarisation in the Ag spacer of a Fe/Ag/Fe tri-laye

RESEARCH OF IRON SULFATE HEAT TREATMENT IN PRESENCE OF ALKALINE REAGENTS AND WATER

The results of the research of the composition and properties of products formed during the heat treatment of the iron sulfate in the in the presence of alkaline reagents (CaO and Na2CO3) and H2O are presented. It is shown, that the formation of α-Fe2O3 using CaO and H2O occurs at a temperature 600–650°С, Na2CO3 and H2O at a temperature 350–450°С. Products of heat treatment have pigment properties: saturated color, spreading capacity 10–12 g/m2, oil absorption 30–40 g/100 g

Thin Film, Near-Surface and Multi-Layer Investigations by Low-Energy μ+SR

ISSN:0304-3843ISSN:0304-3834ISSN:1572-954