电子游戏软件 physicists have discovered a complex landscape of electronic states that can co-exist on a kagome lattice, 类似于高温超导体的, 他们 报道 今年秋天的杂志上 自然.
The focus of the study was a bulk single crystal of a topological kagome metal, known as CsV3Sb5—a metal that becomes superconducting below 2.5开尔文，或者- 455华氏度. The exotic material is built from atomic planes composed of Vanadium atoms arranged on a so-called kagome lattice—a pattern of interlaced triangles and hexagons—stacked on top of one another, with Cesium and Antimony spacer layers between the kagome planes.
The material offers a window into how the physical properties of quantum solids, 比如光的传输, 电传导, 或者说对磁场的响应, relate to the underlying geometry of the atomic lattice structure, according to 电子游戏软件 物理学副教授还有Zeljkovic and 物理学教授王自强 and collaborators from the University of California 圣芭芭拉分校.
An image from 电子游戏软件 researchers shows the scattering and interference of electrons on the surface of a kagome superconductor.
Because its geometry causes destructive interference and “frustrates” the kinetic motion of traversing electrons, kagome lattice materials are prized for offering unique and fertile ground for the study of quantum electronic states described as frustrated, 相关, 和拓扑.
The majority of experimental efforts thus far have focused on kagome magnets. 电子游戏正规平台小组检测的材料没有磁性, which opens the door to investigate how electrons in kagome systems behave in the absence of magnetism. The electronic structure of these crystals can be classified as “topological”, 虽然高导电性使其成为“金属”.
物理学副教授还有Zeljkovic
“This topological metal becomes superconducting at low temperature, which is a very rare occurrence of superconductivity in a kagome material,泽里科维奇说, 该报告的主要合著者, titled “Cascade of 相关 electron states in a kagome superconductor CsV3Sb5.”
In a metal, electrons in the crystal form a liquid state. Electrical conduction happens when the charged liquid flows under a bias voltage. The team used scanning tunneling spectroscopy to probe the quantum interference effects of the electron liquid, 说Zeljkovic, 谁和王一起做了这项电子游戏正规平台, 电子游戏正规平台生李红, 何钊, 2020年在不列颠哥伦比亚省获得物理学博士学位, 以及来自美国的同事.C. 圣芭芭拉分校.
The experiments revealed a “cascade” of symmetry-broken phases of the electron liquid driven by the correlation between the electrons in the material, 电子游戏正规平台小组报告说.
Occurring consecutively as the temperature of the material was lowered, 涟漪, 或者驻波, 首先在电子液体中出现, 被称为电荷密度波, with periodicity different from the underlying atomic lattice. 在较低温度下, a new standing wave component nucleates only along one direction of the crystal axes, such that 电传导 along this direction is different than in any other direction.
These phases develop in the normal state—or the non-superconducting metallic state—and persist below the superconducting transition. The experiments demonstrate that superconductivity in CsV3Sb5 emerges from, 并与, a 相关 quantum electronic state that breaks spatial symmetries of the crystal.
物理学教授王自强
The findings could have strong implications for how the electrons form “Cooper” pairs and turn into a charged superfluid at an even lower temperature, or a superconductor capable of 电传导 without resistance. 在kagome超导体家族中, other research has already suggested the possibility of unconventional electron pairing, 说Zeljkovic.
电子游戏正规平台ers in the field have noted a phenomenon called time-reversal symmetry breaking in CsV3Sb5. This symmetry—which holds that actions would be performed in reverse if time were to run backwards—is typically broken in magnetic materials, but the kagome metal shows no substantial magnetic moments. Zeljkovic said next steps in this research are to understand this apparent contradiction and if and how the electronic states revealed in this recent work are related to time-reversal symmetry breaking.
The level of significance and research into these recently-discovered kagome lattice superconductors is reflected in an associated 自然 article published in the same advance electronic edition. 英国广播公司的王自强也参与撰写了 纸, titled "Roton pair density wave in a strong-coupling kagome superconductor," reports the observation of novel standing waves formed by Cooper pairs with yet another periodicity in the same kagome superconductor, CsV3Sb5.
“The publishing of these two reports side-by-side not only reveals new and broad insights into kagome lattice superconductors, but also signals the high level of interest and excitement surrounding these materials and their unique properties and phenomena, which researchers at 电子游戏软件 and institutions around the world are discovering with increasing frequency,王说.
Ed Hayward | University Communications | December 2021