钽酸钾界面超导的发现与研究进展
摘要
<p indent="0mm">Very recently, superconductivity with a transition temperature (<italic>T</italic><sub>c</sub>) up to <sc>2.2 K</sc> was discovered at KTaO<sub>3</sub> (KTO)-based interfaces. Compared with the classic SrTiO<sub>3</sub> interface superconductors, this new oxide interface superconductivity has a higher <italic>T</italic><sub>c</sub>, a stronger spin-orbit coupling, and a comparable tunability. These excellent properties make KTO interface superconductors an exciting platform to explore rich low-dimensional superconducting physics, as well as to push forward the frontier of oxide electronics. In this paper, we aim to give a brief review of this rapidly developing field of KTO interface superconductors, in order to instruct readers who are interested in, but not familiar with, it. We are not intended to include all the relevant published literatures thoroughly. Rather, we choose materials in a way that can provide readers a consistent story, and let them have a big picture in a short time. For those who are interested in deep details, please refer to the original research papers. The contents are arranged as follows. The first part provides the basic properties of KTO, including its crystalline structure, the dielectric constant, the spin-orbit coupling, orbitals, conduction, etc. The second part reviews the history of the discovery of the KTO interface superconductors. In the third part, we introduce the important physical properties of KTO interface superconductors: (1) The thickness of the interface conducting layer and the two-dimensional superconductivity. (2) The fruitful combinations of a variety of KTO-based interfaces. Here we note that the key role of the deposited films is to supply electrons to the KTO layer near the interface. It is not so crucial whether the deposited films are epitaxial or not. (3) The dependence of superconductivity on the orientations of KTO. (4) The extremely low superfluid density and the strong superconducting fluctu