Direct Observation of High-Temperature Superconductivity in One-Unit-Cell FeSe Films

We prepared one-unit-ceil （1-UC） thick FeSe films on insulating SrTiOa substrates with non-superconducting FeTe protection layers by molecular beam epitaxy for ex situ studies. By direct transport and magnetic measurements, we provide definitive evidence for high temperature superconductivity in the 1-UC FeSe films with an onset Tc above 40 K and an extremely large critical current density fie Jc-1.7× 106 A/cm2 at 2K, which are much higher than Tc-8K and Jc-104 A/cm^2 for bulk FeSe, respectively. Our work may pave the way to enhancing and tailoring superconductivity by interface engineering.     

Electron transport in Dirac and Weyl semimetals

Recently, the Dirac and Weyl semimetals have attracted extensive attention in condensed matter physics due to both the fundamental interest and the potential application of a new generation of electronic devices. Here we review the exotic electrical transport phenomena in Dirac andWeyl semimetals. Section 1 is a brief introduction to the topological semimetals(TSMs). In Section 2 and Section 3, the intriguing transport phenomena in Dirac semimetals(DSMs) andWeyl semimetals(WSMs) are reviewed, respectively. The most widely studied Cd_3A_(s2) and the TaAs family are selected as representatives to show the typical properties of DSMs and WSMs, respectively. Beyond these systems, the advances in other TSM materials,such as ZrTe_5 and the MoTe_2 family, are also introduced. In Section 4, we provide perspectives on the study of TSMs especially on the magnetotransport investigations.     

拓扑材料中对数量子振荡的发现

<正>1930年舒伯尼科夫(Lev Shubnikov)和德哈斯(W. J. de Haas)在铋单晶材料中观测到电阻随磁场的倒数呈周期性变化的规律,被称为Shubnikov—de Haas(SdH)振荡[1],这是人类首次发现的量子振荡。由此开始,量子振荡被物理学界所关注,并逐渐成为揭示新奇物理现象的一个     

纳米尺度下超导体和拓扑绝缘体的电输运特性

超导体和拓扑绝缘体研究是当前凝聚态物理领域中的重大课题.文章重点介绍了作者所在实验室在纳米超导和拓扑绝缘体电输运领域的实验进展,其中包括金属和铁磁纳米线中的超导近邻效应、半金属纳米线中的新奇超导特性、拓扑绝缘体薄膜中的量子输运以及超导态-拓扑量子态的相互作用等,并对该领域的进一步发展进行了展望.