Two-Dimensional Quantum Transport in Free-Standing InSb Nanosheets.

Low-dimensional narrow band gap III-V compound semiconductors, such as InAs and InSb, have attracted much attention as one of promising platforms for studying Majorana zero modes and non-Abelian statistics relevant for topological quantum computation. So far, most of experimental studies were performed on hybrid devices based on one-dimensional semiconductor nanowires. In order to build complex topological circuits toward scalable quantum computing, exploring high-mobility two-dimensional (2D) III-V compound electron system with strong spin-orbit coupling is highly desirable. Here, we study quantum transport in high-mobility InSb nanosheet grown by molecular-beam epitaxy. The observations of Shubnikov-de Hass oscillations and quantum Hall states, together with the angular dependence of magnetotransport measurements, provide the evidence for the 2D nature of electronic states in InSb nanosheet. The presence of strong spin-orbit coupling in the InSb nanosheet is verified by the low-field magnetotransport measurements, characterized by weak antilocalization effect. Finally, we demonstrate the realization of high-quality InSb nanosheet-superconductor junctions with transparent interface. Our results not only advance the study of 2D quantum transport but also open up opportunities for developing hybrid topological devices based on 2D semiconducting nanosheets with strong spin-orbit coupling.

Cloning and identification of a female-specific DNA marker in Paramisgurnus dabryanus.

Paramisgurnus dabryanus (Cypriniformes; Cobitidae), has been an emerging aquaculture species in China since the 1990s. In this study, random amplified polymorphic DNA fingerprinting with 220 primers was used to identify a sex-specific DNA marker in pooled DNA and individual DNA samples from male and female P. dabryanus. One primer, S2115, produced a novel sex-specific DNA fragment found only in tested females. This female-specific fragment was 917 bp with 36% GC content, and was named Pdff1. To further validate the authenticity of this female-specific marker for sexing, two PCR primers (pdff1-F and -R) were designed according to the cloned female-specific sequence. Amplification showed bands specific for females. Dot blot and Southern blot hybridization experiments both displayed female specificity using this marker as the probe. Two other P. dabryanus populations were tested by dot blot hybridization with the Pdff1 probe. The hybridization signals were seen in 33 or 43% of males in addition to all females in the Jinan and Xichuan populations, respectively. We propose to use this sex-specific marker to rapidly and specifically identify the gender of P. dabryanus from the ancient Yellow River Wetland in Yanjin, Henan Province. Our results could assist in cloning sex-specific chromosomal regions.

Signature of quantum Griffiths singularity state in a layered quasi-one-dimensional superconductor.

Quantum Griffiths singularity was theoretically proposed to interpret the phenomenon of divergent dynamical exponent in quantum phase transitions. It has been discovered experimentally in three-dimensional (3D) magnetic metal systems and two-dimensional (2D) superconductors. But, whether this state exists in lower dimensional systems remains elusive. Here, we report the signature of quantum Griffiths singularity state in quasi-one-dimensional (1D) Ta2PdS5 nanowires. The superconducting critical field shows a strong anisotropic behavior and a violation of the Pauli limit in a parallel magnetic field configuration. Current-voltage measurements exhibit hysteresis loops and a series of multiple voltage steps in transition to the normal state, indicating a quasi-1D nature of the superconductivity. Surprisingly, the nanowire undergoes a superconductor-metal transition when the magnetic field increases. Upon approaching the zero-temperature quantum critical point, the system uncovers the signature of the quantum Griffiths singularity state arising from enhanced quenched disorders, where the dynamical critical exponent becomes diverging rather than being constant.