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Background The immunogenicity and safety following standard two-dose SARS-CoV-2 vaccination in patients with immune-mediated inflammatory diseases (IMIDs) are not well characterised, and data on third dose vaccination in this patient group are currently lacking. Methods This prospective, observational cohort study included adult patients on immunosuppressive therapy for Crohn’s disease (CD), ulcerative colitis (UC), rheumatoid arthritis (RA), spondyloarthritis (SpA), psoriatic arthritis (PsA), and healthy controls receiving standard two-dose SARS CoV-2 vaccination. Patients with a weak serologic response ( Results A total of 1641 patients (280 CD, 195 UC, 566 RA, 305 SpA, 295 PsA, median age 52 [IQR 40–63], 899 [55%] women), and 1114 healthy controls (median age 43 [IQR 32–55], 854 [77%] women), were included in the study. After standard SARS-CoV-2 two dose vaccination, 1504 (91%) patients compared to 1096 (98%) healthy controls (p Conclusion Response rate as well as anti-RBD levels were lower in IMID patients than healthy controls following standard vaccination. Third dose vaccination in serologically weak responders was safe and resulted in a response in most patients. Our data facilitate identification of patient groups at risk of an attenuated vaccine response eligible for post-vaccination serological monitoring. The data also support a third vaccine dose following standard SARS-CoV-2 vaccination to weak-responding IMID-patients.

We report on investigations of the superconducting energy gap of the A15 superconductor Nb_3Sn by point-contact spectroscopy of breakjunctions. The voltage-dependent differential conductance dI/dV reveals features of a second energy gap besides the energy gap known from previous tunnel measurements with maxima at \Delta_1=3.92 +/- 0.16 meV and \Delta_2=0.85 +/- 0.17 meV as derived from a histogram summarizing the data of more than 60 contacts. These findings are the first spectroscopic evidence that Nb_3Sn belongs to the class of two-band superconductors and they are in line with low-temperature specific-heat measurements on Nb_3Sn.

Usually the electronic band structure is a rather robust property of the metallic state, especially when applying magnetic fields. For the half-Heusler compounds Ce1−xLaxBiPt, however, we observe magnetic-field-induced band-structure changes in strong magnetic fields. This is evidenced by Shubnikov-de Haas (SdH) and Hall-effect measurements performed in pulsed magnetic fields up to 70 Tesla. Above sample-dependent threshold fields, both in CeBiPt as well as in Ce0.95La0.05BiPt single crystals, the SdH signals vanish and the Hall coefficients change drastically. Such kind of effects are absent in the non-4f compound LaBiPt. Electronic-band-structure calculations can well explain the observed behavior by a 4f-polarization-induced Fermi-surface modification, i.e., a fieldinduced Lifshitz transition.1,2 1 N. Kozlova et al., Phys. Rev. Lett. 95, 086403 (2005). 2 J. Wosnitza et al., New J. Phys. 8, 174 (2006).

We report on the Fermi surface in the correlated half-Heusler compounds Ce1xLaxBiPt. In CeBiPt, as well as in Ce0:95La0:05BiPt, we find a temperature-dependent Fermi-surface topology. In addition, we observe a field-induced change of the electronic band structure as discovered by electrical-transport measurements in pulsed magnetic fields. For magnetic fields above 25 T, in a simple one band picture, the charge-carrier concentration determined from Hall-effect measurements increases nearly 30%, whereas the Shubnikov-de Haas (SdH) signal disappears at the same field. In the non-4f compound LaBiPt the Fermi surface remains unaffected, suggesting that these features are intimately related to the Ce 4f electrons. Electronic band–structure calculations point to a 4f-polarization-induced change of the Fermi-surface topology.

The half-Heusler compounds CeBiPt and LaBiPt are semimetals with very low charge-carrier concentrations as evidenced by Shubnikov–de Haas (SdH) and Hall-effect measurements. Neutron-scattering results reveal a simple antiferromagnetic structure in CeBiPt below TN = 1.15K. The band structure of CeBiPt sensitively depends on temperature, magnetic field and stoichiometry. Above a certain, sample-dependent, threshold field (B > 25 T), the SdH signal disappears and the Hall coefficient reduces significantly. These effects are absent in the non-4f compound LaBiPt. Electronic-band-structure calculations can well explain the observed behaviour by a 4f-polarization-induced Fermi-surface modification.

We report on the Fermi surface in the correlated half-Heusler compounds Ce1-xLaxBiPt. In CeBiPt, as well as in Ce0.95La0.05BiPt, we find a temperature-dependent Fermi-surface topology. In addition, we observe a field-induced change of the electronic band structure as discovered by electrical-transport measurements in pulsed magnetic fields. For magnetic fields above about 25 T, the charge-carrier concentration determined from Hall-effect measurements increases nearly 30%, whereas the Shubnikovde Haas (SdH) signal disappears at the same field [1]. In the non-4f compound LaBiPt the Fermi surface remains unaffected, suggesting that these features are intimately related to the Ce 4f electrons. Electronic band-structure calculations point to a 4f-polarization-induced change of the Fermi-surface topology.

We report on the Fermi surface in the correlated half-Heusler compound Ce1-xLaxBiPt. In CeBiPt we find a field-induced change of the electronic band structure as discovered by electrical-transport measurements in pulsed magnetic fields. For magnetic fields above ca 25 T, the charge-carrier concentration determined from Hall-effect measurements increases nearly 30%, whereas the Shubnikov-de Haas (SdH) signal disappears at the same field. In the non-4f compound LaBiPt the Fermi surface remains unaffected, suggesting that these features are intimately related to the Ce 4F electrons. Electronic band-structure calculations point to a 4f-polarization-induced change of the Fermi-surfache topology. In order to test this hypothesis, we have measured the (SdH) signal in a Ce0.95La0.05BiPt sample with a low La concentration.

We report on a field-induced change of the electronic band structure of CeBiPt as evidenced by electrical-transport measurements in pulsed magnetic fields. Above similar to 25 T, the charge-carrier concentration increases nearly 30% with a concomitant disappearance of the Shubnikov-de Haas signal. These features are intimately related to the Ce 4f electrons since for the non-4f compound LaBiPt the Fermi surface remains unaffected. Electronic band-structure calculations point to a 4f-polarization-induced change of the Fermi-surface topology.

We present new specific heat data for Nb3Sn, a well-known technically applied superconductor with a critical temperature T_c ~ 18 K, in the temperature range from 1.2 to 200 K in zero magnetic field, and from 1.5 to 22 K in fields H, 16 pages, 8 figures

Electrical-transport measurements of the semimetal CeBiPt in magnetic fields up to 60 T reveal a drastic change of the electronic band structure. The oscillating Shubnikov-de Haas signal vanishes above about 25 T although the quantum limit is not yet reached. Above this field the magneto resistance rises strongly independent of angle and temperature. These unique features are caused by the Cc 4f electrons as evidenced by the absence of any unconventional behavior in the sister compound LaBiPt.

Shubnikov--de Haas (SdH) and Hall-effect measurements of CeBiPt and LaBiPt reveal the presence of simple and very small Fermi surfaces with hole-like charge carriers for both semimetals. In the magnetic material, CeBiPt, we observe a strong temperature dependence of the SdH frequency. This highly unusual effect might be connected with an internal exchange field within the material and a strongly spin-dependent scattering of the charge carriers., 4 pages, 4 figures

The superconducting gap function of Sr$_2$RuO$_4$ was investigated by means of quasiparticle reflection and transmission at the normal conductor-superconductor interface of Sr$_2$RuO$_4$-Pt point contacts. We found two distinguishly different types of $dV/dI$ vs $V$ spectra either with a double-minimum structure or with a zero-bias conductance anomaly. Both types of spectra are expected in the limit of high and low transparency, respectively, of the interface barrier between a normal metal and a spin-triplet superconductor. Together with the temperature dependence of the spectra this result strongly supports a spin-triplet superconducting order parameter for Sr$_2$RuO$_4$., Comment: 4 pages, 4 figures, published version

Experimental magneto-optical Kerr effect spectra of Mn-implanted Ge samples are interpreted using an ab-initio theoretical model based on density functional theory. The presence of Mn in the Ge matrix is accounted for considering either Mn precipitation as Mn5Ge3 nanoparticles or as perfect dilution. The Mn concentration profile in the sample is also considered in the theoretical model. The computational results are in good qualitative agreement if Mn5Ge3 nanocluster formation is assumed. The effect of partial etching of the implanted region is also studied by comparing our experimental and theoretical MOKE spectra data.

[Co(0.6 nm)/ZnO(x nm)]60 (x= 0.4nm, 3nm) films were deposited on glass substrates then annealed in a vacuum. The magnetisation of the films increased with annealing but not the magnitude of the magneto-optical signals. The dielectric functions Im epsilonxy for the films were calculated using the MCD spectra. A Maxwell Garnett theory of a metallic Co/ZnO mixture is presented. The extent to which this explains the MCD spectra taken on the films is discussed.

In der Arbeit wird der Aufbau eines RTM, das bei tiefen Temperaturen und großen magnetischen Feldern $B>10\,$T funktionstüchtig ist, beschrieben. Untersucht wurden die Schwerfermionensupraleiter CeCoIn$_5$ und Sr$_2$RuO$_4$. Ein weiterer Teil der Arbeit beschäftigt sich mit Punktkontaktspektroskopie an den Eisenpnictidsupraleiter Ba$_{1-x}$K$_x$Fe$_2$As$_2$ und Ba(Fe,Co)$_2$As$_2$.