[en] Radiobiological studies on cell monolayers irradiated by charged particles need to determine the number and position of particle traversals. Solid state nuclear track detectors used as basic substrate for the cell layers are in principle suitable for this purpose. The detector foils must be as thin as possible but still guaranteeing mechanical stability. Two types of LR-115, red coloured and colourless, were tested in the present work. The studies aimed at optimisation of the etching conditions and determination of the registration efficiency for alpha particles in a wide range of energies and angles of incidence. Specific requirements have to be fulfilled for application of the detector foils under the environmental conditions of radiobiological experiments. Most important are biocompatibility between detector and cells and registration properties insensible against special treatments, as UV sterilisation and cell plating prior to irradiation as well as cell incubation after the irradiation. The experimental studies performed with alpha particles showed that environmental conditions of radiobiological experiments do not change the registration properties of LR-115 detectors significantly

[en] We report a comparative study of the low-temperature thermal expansion and magnetostriction of the non-Fermi liquid (NFL) system YbRh₂(Si_1-xGe_x)₂ (x=0 and nominally 0.05). The undoped compound (x=0) shows a sharp phase transition anomaly, related to antiferromagnetic ordering at T_N=70 mK, that is suppressed by a small critical field B_c=0.06 T (B perpendicular c). By contrast, very tiny anomalies at T_N=(20±5) mK and B_c=(0.027±0.005) T are observed in the x=0.05 system. The NFL behavior above T_N is not affected by the Ge substitution

[en] We present DC-magnetization, M(B), magnetostriction, ΔL(B)/L, and magnetoresistance ρ(T,B) measurements on high-quality single crystals of YbRh₂Si₂ in magnetic fields up to 18 T and at temperatures down to 15 mK. At B^starf∼9.5 T, both M(B) and ΔL(B)/L show pronounced changes of their slopes, indicative for a broadened phase transition. For fields above B^starf, the coefficient A of the Fermi liquid behavior Δρ=ρ₀+A(B)T² is reduced to very small values, indicating the suppression of the Heavy Fermion state

[en] We present the first study of codoped iron-arsenide superconductors of the 122 family (Sr/Ba)_1-xK_xFe_2-yCo_yAs₂ with the purpose to increase the upper critical field H_c2 compared to single doped Sr/BaFe₂As₂ materials. H_c2 was investigated by measuring the magnetoresistance in high pulsed magnetic fields up to 64 T. We find, that H_c2 extrapolated to T=0 is indeed enhanced significantly to 90 T for polycrystalline samples of Ba_0.55K_0.45Fe_1.95Co_0.05As₂ compared to 75 T for Ba_0.55K_0.45Fe₂As₂ and BaFe_1.8Co_0.2As₂ single crystals. Codoping thus is a promising way for the systematic optimization of iron-arsenic based superconductors for magnetic-field and high-current applications.

No abstract available

[en] The rare-earth monopnictide materials include many examples of strongly correlated electron materials with low carrier density and magnetic ground states. The semimetal GdSb orders antiferromagnetically below 23.4 K, and at low temperature a fully polarised ferromagnetic state is reached for applied magnetic fields greater than the saturation field, H_s, of 33.5 T. Magnetostriction measurements in pulsed magnetic fields up to 55 T show that the magnetoelastic coupling to the Gd³⁺ moment system changes sign on crossing H_s. We also observe large-amplitude quantum oscillations of the sample length.

[en] Here, we present magnetization measurements on Sr4Ru3O10 as a function of temperature and magnetic field applied perpendicular to the magnetic easy c-axis inside the ferromagnetic phase. Peculiar metamagnetism evolves in Sr4Ru3O10 below the ferromagnetic transition TC as a double step in the magnetization at two critical fields Hc1 and Hc2. We map the H-T phase diagram with special focus on the temperature range 50 K ≤T≤TC. We find that the critical field Hc1(T) connects the field and temperature axes of the phase diagram, whereas the Hc2 boundary starts at 2.8 T for the lowest temperatures and ends in a critical endpoint at (1 T; 80 K). We also conclude from the temperature dependence of the ratio Hc1Hc2(T) that the double metamagnetic transition is an intrinsic effect of the material and it is not caused by sample stacking faults such as twinning or partial in-plane rotation between layers.

[en] We report on the design and successful testing (up to 55 T) of a 60 T long-pulse (LP) magnet with a pulse duration of 1500 ms at the Hochfeld-Magnetlabor Dresden. This magnet has the capability of producing magnetic fields with time and homogeneity characteristics suitable to host specific-heat and nuclear magnetic resonance (NMR) experiments. We describe the development of a specific-heat probe for this magnet, which uses the quasi-adiabatic heat-pulse method and enables magnetocaloric-effect measurements. Furthermore, we report the implementation of a NMR setup, consisting of home-built probe and spectrometer. Both experimental devices were tested successfully in the LP magnet up to 31 and 44 T, respectively. (paper)

No abstract available

[en] Substitution of Yb-atoms with La in Yb_1-xLa_xRh₂Si₂ leads to an increase of the Kondo temperature and suppression of antiferromagnetic order. Here, we present low-temperature (T>=20mK) electrical resistivity measurements on x=0.05 and x=0.1 single crystals at various magnetic fields. For x=0.05, a linear temperature dependence is observed for 0=< B=<0.04T which turns into Landau Fermi liquid (LFL) behavior Δρ=AT² at larger fields. For x=0.1, LFL behavior is found already at 0.02T. The evolution of A(B) suggests x=0.05 and x=0.1 to be located on the magnetically ordered and LFL side of the quantum critical point, respectively