Zero energy bound states in tunneling conductance spectra at the interface of an s-wave superconductor and a topological insulator in NbN-Bi2Se3Bi_2Se_3-Au thin film junctions

Measurements of conductance spectra in a superconductor - topological insulator - normal metal thin film junctions of NbN-$\rm Bi_2Se_3$-Au are reported. Junctions with ex-situ and in-situ prepared $\rm NbN-Bi_2Se_3$ interfaces were studied. At low temperatures, all the ex-situ junctions showed coherence peaks in their conductance spectra, but imbedded robust zero bias conductance peaks were observed only in junctions with a metallic or a metal to insulator transition below $\rm T_c$ of the NbN electrode. The in-situ junctions which had about two orders of magnitude lower resistance at low temperatures, generally showed flat conductance spectra at low bias, with no coherence or broad Andreev peaks, since the critical current of the NbN electrode was reached first, at voltage bias below the energy gap of the superconductor. A weak zero bias conductance peak however, was observed in one of these junctions. We conclude that significant tunneling barriers, as in the ex-situ prepared junctions, are essential for the observation of coherence peaks and the zero energy bound states. The later seem to originate in the $\rm Bi_2Se_3$-NbN interface, as they are absent in reference Au-NbN junctions without the topological layer sandwiched in between.Comment: Published versio

Critical current measurements in superconductor - ferromagnet - superconductor junctions of YBa2Cu3OyYBa_2Cu_3O_y-SrRuO3SrRuO_3-YBa2Cu3OyYBa_2Cu_3O_y: No evidence for a dominant proximity induced triplet superconductivity in the ferromagnetic barrier

Transport measurements in ramp-type junctions of $YBa_2Cu_3O_y-SrRuO_3-YBa_2Cu_3O_y$ with $T_c$ values of either 80-90 K or 60-70 K are reported. In both type of junctions but without a barrier ("shorts"), the supercurrent densities at 4.2 K reached 7.5 and 3.5 MA/cm$^2$, respectively, indicating the high quality of the fabrication process. Plots of the critical current versus thickness of the ferromagnetic barrier at 4.2 K show exponential decays with decay lengths of 1.1 nm for the 90 K phase and 1.4 nm for the 60 K phase, which are much shorter than the relevant coherence lengths $\xi_F\sim 5-6$ nm or $\xi_N\sim$16 nm of $SrRuO_3$. We thus conclude that there is no dominant proximity induced triplet superconductivity in the ferromagnet in our junctions.Comment: 5 figure

Signature of proximity-induced p

In the search for Majorana fermions in proximity-induced topological superconducting junctions, we happened to find a signature of same-spin triplet superconductivity which appears to dominate these elusive elementary excitations. Thin-film junctions and bilayers of the doped topological insulator $\text{Bi}_2\text{Se}_3$ and the s-wave superconductor NbN exhibit conductance spectra with coexisting prominent zero-bias and coherence peaks. Various tunneling models with different pair potentials have failed to fit our data, except for the triplet $p_x+ip_y$ pair potential, which breaks time-reversal symmetry, that yielded reasonably good fits. This provides supporting evidence for proximity-induced triplet superconductivity in the $\text{Bi}_2\text{Se}_3$ layer near the interface with the NbN film

Signature of proximity-induced p x

Thin film junctions and bilayers of the doped topological insulator $\rm Bi_2Se_3$ and the s-wave superconductor NbN were found to exhibit conductance spectra with prominent zero bias and coherence peaks. Various tunneling models with different pair potentials have failed to fit our data, except for the triplet $p_x+ip_y$ pair potential, which breaks time reversal symmetry, but yielded reasonably good fits. This provides evidence for proximity induced triplet superconductivity in the $\rm Bi_2Se_3$ layer near the interface with the NbN film.Comment: Accepted for publication in Europhysics Letter

Subacute Thyroiditis—Still a Diagnostic Challenge: Data from an Observational Study

Background: Subacute thyroiditis (SAT) is a relatively common cause of thyroid disease. However, only a few studies evaluating SAT have been published in recent years with varying diagnostic criteria. We evaluate the clinical presentation and long-term outcome of isotope scan-confirmed SAT. Methods: A retrospective study of 38 patients with isotope scan-confirmed SAT was performed at a single isotope department. All patients were contacted for long-term follow-up. Results: The female/male ratio was 1.4:1, and mean age was 47 ± 14 years and 62 ± 12 years in women and men, respectively (p = 0.002). Almost half of the cases (42%) occurred during the summer. The most common symptoms were neck pain (74%) and weakness (61%). Palpitations, weight loss, heat intolerance, and sweating appeared in 50%, 42%, 21%, and 21%, respectively. Only half of the patients reported fever. TSH level was low in all patients, and mean FT4 and FT3 level were about twice the upper limit of normal range. Elevated CRP and ESR occurred in the majority (88%) of patients. The mean time period between the first clinic visit and performing thyroid function tests was 8 ± 7 days. One-third of the patients initially received a diagnosis of upper respiratory tract infection (URI). NSAIDs and steroids were prescribed to 47% and 8% of patients, respectively. Long-term follow-up of 33.5 months (range 9–52) revealed that 25% remained with subclinical or overt hypothyroidism. Conclusions: These data demonstrate that although SAT is a common entity, there is still a significant delay in diagnosis, and in a third of our patients, the initial diagnosis was URI, with 25% developing long-term hypothyroidism

Following the COVID-19 Experience, Many Patients with Type 1 Diabetes Wish to Use Telemedicine in a Hybrid Format

Background: The COVID-19 pandemic has brought to light both challenges and unique opportunities regarding type 1 diabetes (T1D) management, including the usage of telemedicine platforms. Methods: This study was conducted in a tertiary hospital diabetes clinic. All consecutive T1D patients during March and June 2021 were asked to fill out a structured anonymous questionnaire that aimed to determine their preference regarding continuous use of a virtual platform. Results: In total, 126 T1D patients answered the questionnaire, of whom 51% were under the age of 40, half were men, half used insulin pumps, and 69% used continuous glucose monitoring. During the pandemic, the exposure of patients to virtual visits has grown about twofold, from 29% to 53%. Of the respondents, 49% expressed an interest in future usage of a virtual platform, but most of them preferred use in a hybrid manner. We found an association between preference to use telemedicine in the future and younger age, previous virtual platform experience, and confidence in being able to download data. Conclusions: Our data demonstrate that the COVID-19 experience has led to a growing interest of T1D patients in using the hybrid format of telemedicine. However, we still need to better understand who will benefit most from this platform and assess its cost-effectiveness and organization