Experimental realization of SQUIDs with topological insulator junctions

We demonstrate topological insulator (Bi$_2$Te$_3$) dc SQUIDs, based on superconducting Nb leads coupled to nano-fabricated Nb-Bi$_2$Te$_3$-Nb Josephson junctions. The high reproducibility and controllability of the fabrication process allows the creation of dc SQUIDs with parameters that are in agreement with design values. Clear critical current modulation of both the junctions and the SQUID with applied magnetic fields have been observed. We show that the SQUIDs have a periodicity in the voltage-flux characteristic of $\Phi_0$, of relevance to the ongoing pursuit of realizing interferometers for the detection of Majorana fermions in superconductor- topological insulator structures

Josephson supercurrent in a topological insulator without a bulk shunt

A Josephson supercurrent has been induced into the three-dimensional topological insulator Bi1.5Sb0.5Te1.7Se1.3. We show that the transport in Bi1.5Sb0.5Te1.7Se1.3 exfoliated flakes is dominated by surface states and that the bulk conductivity can be neglected at the temperatures where we study the proximity induced superconductivity. We prepared Josephson junctions with widths in the order of 40 nm and lengths in the order of 50 to 80 nm on several Bi1.5Sb0.5Te1.7Se1.3 flakes and measured down to 30 mK. The Fraunhofer patterns unequivocally reveal that the supercurrent is a Josephson supercurrent. The measured critical currents are reproducibly observed on different devices and upon multiple cooldowns, and the critical current dependence on temperature as well as magnetic field can be well explained by diffusive transport models and geometric effects

The AARTFAAC 60 MHz transients survey

We report the experimental setup and overall results of the AARTFAAC wide-field radio survey, which consists of observing the sky within 50$^\circ$ of Zenith, with a bandwidth of 3.2$\,$MHz, at a cadence of 1$\,$s, for 545$\,$h. This yielded nearly 4 million snapshots, two per second, of on average 4800 square degrees and a sensitivity of around 60$\,$Jy. We find two populations of transient events, one originating from PSR$\,$B0950$+$08 and one from strong ionospheric lensing events, as well as a single strong candidate for an extragalactic transient, with a peak flux density of $80\pm30$$\,$Jy and a dispersion measure of $73\pm3\,\mathrm{~pc~cm^{-3}}$, We also set a strong upper limit of 1.1 all-sky per day to the rate of any other populations of fast, bright transients. Lastly, we constrain some previously detected types of transient sources by comparing our detections and limits with other low-frequency radio transient surveys.Comment: 10 pages, 8 figures. Published by MNRA

Simultaneous Epstein Barr Virus and Cytomegalovirus Infection Accompanied by Leiomyomatous Change in a Well-Differentiated Liposarcoma in a Patient With Long-Term Corticosteroid Treatment

Patient. A 59-year-old woman presented with a large tumour of the abdominal wall. She had been taking corticosteroids for severe chronic obstructive pulmonary disease for 15 years. On CT scan the tumour had the characteristics of lipomatous tissue with a dense core

Accurate evaluation of the interstitial KKR-Green function

It is shown that the Brillouin zone integral for the interstitial KKR-Green function can be evaluated accurately by taking proper care of the free-electron singularities in the integrand. The proposed method combines two recently developed methods, a supermatrix method and a subtraction method. This combination appears to provide a major improvement compared with an earlier proposal based on the subtraction method only. By this the barrier preventing the study of important interstitial-like defects, such as an electromigrating atom halfway along its jump path, can be considered as being razed.Comment: 23 pages, RevTe