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We report a comprehensive de Haas-van Alphen (dHvA) study of the heavy-fermion material CeRhIn_{5} in magnetic fields up to 70 T. Several dHvA frequencies gradually emerge at high fields as a result of magnetic breakdown. Among them is the thermodynamically important β_{1} branch, which has not been observed so far. Comparison of our angle-dependent dHvA spectra with those of the non-4f compound LaRhIn_{5} and with band-structure calculations evidences that the Ce 4f electrons in CeRhIn_{5} remain localized over the whole field range. This rules out any significant Fermi-surface reconstruction, either at the suggested nematic phase transition at B^{*}≈30 T or at the putative quantum critical point at B_{c}≃50 T. Our results rather demonstrate the robustness of the Fermi surface and the localized nature of the 4f electrons inside and outside of the antiferromagnetic phase.

Angular-dependent de Haas-van Alphen measurements allow the mapping of Fermi surfaces in great detail with high accuracy. Density functional electronic-structure calculations can be carried out with high precision, but depend crucially on the used structural information and the applied calculational approximations. We report in a detailed study the sensitivity of the calculated electronic band structure of the 122 compound LaFe

Carbon doping of magnesium diboride resulting in the Mg(B 0.9 C 0.1 ) 2 stoichiometry leads to the superconducting transition temperature T c =22 K which is about 17 K less than in the pure MgB 2 . We present the magnetotransport measurements on the doped polycrystalline samples up to 23 T in the temperature range from 1.5 K. Despite the significantly lowered T c the upper critical magnetic field H c2 is much higher here than in the pure MgB 2 and achieves values of about 25–30 Tesla at low temperatures comparable to the MgB 2 samples with the highest level of impurity scattering. The anomalous temperature dependence H c2 ( T ) revealing a positive curvature in the overall temperature range is discussed in the framework of the two-gap superconductivity, which is still present here. As another possibility an importance of the critical fluctuations is considered within the Ullah–Dorsey scaling model.

Large-sized simulators of magnetic fields of stations for degaussing ships and short circuits of high-voltage transmission lines providing target parameters of magnetic field in a volume of 5 × 5 × 10 m are developed and constructed. To form the magnetic field of a short circuit of high-voltage transmission lines, an oscillatory contour with feed from a network is applied. The magnetic field simulator includes two powerful thyristor reversible converters. Both simulators work on a uniform magnetizing system.

We have prepared high-quality epitaxial thin films of CaRuO$_3$ with residual resistivity ratios up to 55. Shubnikov-de Haas oscillations in the magnetoresistance and a $T^2$ temperature dependence in the electrical resistivity only below 1.5 K, whose coefficient is substantially suppressed in large magnetic fields, establish CaRuO$_3$ as a Fermi liquid (FL) with anomalously low coherence scale. Non-Fermi liquid (NFL) $T^{3/2}$ dependence is found between 2 and 25 K. The high sample quality allows access to the intrinsic electronic properties via THz spectroscopy. For frequencies below 0.6 THz, the conductivity is Drude-like and can be modeled by FL concepts, while for higher frequencies non-Drude behavior, inconsistent with FL predictions, is found. This establishes CaRuO$_3$ as a prime example of optical NFL behavior in the THz range.

We report on semiclassical angle-dependent magnetoresistance oscillations and the Shubnikov-de Haas effect in the electron-overdoped cuprate superconductor Nd(2-x)CexCuO4. Our data provide convincing evidence for magnetic breakdown in the system. This shows that a reconstructed multiply connected Fermi surface persists, at least at strong magnetic fields, up to the highest doping level of the superconducting regime.

The Seebeck and Nernst coefficients S and nu of the cuprate superconductor YBa{2}Cu{3}O{y} (YBCO) were measured in a single crystal with doping p=0.12 in magnetic fields up to H=28 T. Down to T=9 K, nu becomes independent of field by H approximately 30 T, showing that superconducting fluctuations have become negligible. In this field-induced normal state, S/T and nu/T are both large and negative in the T--0 limit, with the magnitude and sign of S/T consistent with the small electronlike Fermi surface pocket detected previously by quantum oscillations and the Hall effect. The change of sign in S(T) at T approximately 50 K is remarkably similar to that observed in La2-xBaxCuO4, La{2-x-y}Nd{y}Sr_{x}CuO{4}, and La{2-x-y}Eu{y}Sr{x}CuO{4}, where it is clearly associated with the onset of stripe order. We propose that a similar density-wave mechanism causes the Fermi surface reconstruction in YBCO.

Heat-capacity measurements of a 39 microg MgB2 single crystal in fields up to 14 T and below 3 K allow the determination of the low-temperature linear term of the specific heat, its field dependence, and its anisotropy. Our results are compatible with two-band superconductivity, the band carrying the smaller gap being isotropic, that carrying the larger gap having an anisotropy of approximately 5. Three different upper critical fields are thus needed to describe the superconducting state of MgB2.

The crucial question of whether the superconducting phase found in the spin ladder compound Sr14-xCaxCu24O41 is due to the natural pair forming mechanism predicted for isolated ladders is still open. A recent experimental breakthrough enables us to perform calorimetric measurements under hydrostatic pressure in a diamond anvil cell. We report here measurements on the compound Sr25Ca11.5CU24O41 which show that the superconductivity is a bulk property and that antiferromagnetic order and superconductivity coexist over a wide pressure range. At the pressure where the sample becomes superconducting, the variation of the Neel temperature is continuous. However at high pressure there is a sharp increase of TN, and TN and Tc become comparable. The possible nature of the superconducting phase is discussed in the light of these results and previous measurements of the upper critical field

The absence of simple examples of superconductivity adjoining itinerant-electron ferromagnetism in the phase diagram has for many years cast doubt on the validity of conventional models of magnetically mediated superconductivity. On closer examination, however, very few systems have been studied in the extreme conditions of purity, proximity to the ferromagnetic state and very low temperatures required to test the theory definitively. Here we report the observation of superconductivity on the border of ferromagnetism in a pure system, UGe2, which is known to be qualitatively similar to the classic d-electron ferromagnets. The superconductivity that we observe below 1 K, in a limited pressure range on the border of ferromagnetism, seems to arise from the same electrons that produce band magnetism. In this case, superconductivity is most naturally understood in terms of magnetic as opposed to lattice interactions, and by a spin-triplet rather than the spin-singlet pairing normally associated with nearly antiferromagnetic metals.

We present de Haas-van Alphen measurements of the nonmagnetic borocarbide superconductor LuNi2B2C. The electronic band structure is extracted from the magnetic quantum oscillations in the normal state. In accordance with previous investigations we find a complex band structure with different open and closed Fermi-surface sheets. From the temperature dependence of the oscillations amplitude the effective mass of the single bands can be determined. Due to many-body interactions we observe enhancements of the effective masses compared to the results by full-potential-density-functional calculations. Therefore, we are able to determine the angular dependence of the interaction strength for the different bands separately.

In this letter we present the effect of neutron irradiation up to fluences of 3.9 1019 n/cm2 on the superconducting properties of MgB2. In order to obtain a disorder structure homogeneously distributed, the experiment was carried out on bulk samples prepared with the 11B isotope. Up to fluences of 1018 n/cm2 the critical temperature is slightly diminished (36 K) and the superconducting properties are significantly improved; the upper critical field is increased from 13.5 T to 20.3 T at 12 K and the irreversibility field is doubled at 5 K. For larger neutron fluences the critical temperature is suppressed down to 12 K and the superconducting properties come out strongly degraded.

During October-November 1935, I had the opportunity to observe a number of cases of acute spontaneous infectious damage to the nervous system. The clinical picture in my cases was typical and presented no difficulties in diagnostic terms. The current was also typical. The interesting thing is that these cases were observed for a very short period of time, in the form of an outbreak. In addition, some cases represent the cerebellar localization of encephalitis. This form, judging by the literature data and my personal experience, is relatively rare. Even with acute multiple diseases of the nervous system such as encephalomyelitis, where we have many lesions in various parts of the brain and spinal cord, foci in the cerebellum are not so common. All the more rare are cases where we have an isolated or sharply predominant lesion of the cerebellum by an encephalitic process.

The first attempt at treating neuroses with microdoses of bromine belongs to Birman and Siegel. In 10 cases of neurasthenia, these authors used 1/2% bromine solution, 1 tablespoon, 2 times a day, for 3-5 weeks, and in almost all cases received positive results. Subsequently, Weinberg and Birman tested this method of treatment on a larger number of patients at a dosage of bromine of 0.25% and sometimes 0.1%, and of 31 cases of neurasthenia, they obtained a positive result in 28 cases. The therapeutic effect was absent or insignificant in 3 cases of neurasthenia, in 1 case with reactive depression and in 8 cases of constitutional hysteria.