Chinese scientists lead breakthrough in magnetic superconductivity, setting a new record for spatial energy resolution in electron spectroscopy

On August 23, the Department of Physics of Southern University of Science and Technology issued a press release yesterday (August 22), stating that the chiral cage-like superconducting oscillations observed by its Quantum Singularity and Evolved Matter Laboratory set a new world record for the spatial energy resolution of electronic spectroscopy (1μeV).

Project Background

Magnetism and superconductivity are generally considered to be two mutually exclusive quantum states. However, as early as 1958, physics masters Matthias and Anderson considered the connection between the two in lattice frustrated systems and proposed the possibility of magnetic superconductivity.

The kagome lattice is a pattern of triangles connected at the vertices and is a lattice structure with geometric frustration.

Project Team Introduction

The project is led by the research group of Associate Professor Yin Jiaxin from the Department of Physics at Southern University of Science and Technology, and an international team consisting of scholars from China, Switzerland, Germany and Singapore has been formed.

Deng Hanbin, a postdoctoral fellow in the Department of Physics at SUSTech, is the first author of the paper, and SUSTech is the first unit of the paper.

Other members of Yin Jiaxin's research team include Qin Hailang, an associate researcher at the Quantum Center, and Liu Guowei and Yang Tianyu, postdoctoral fellows from the Department of Physics at SUSTech.

Project History

Since 2018, Yin Jiaxin and his collaborators have reported a series of research results on quantum control in cage magnets and superconductors, advancing a new direction of cutting-edge research: topological cage materials.

In a review article published in Nature in 2022, Yin Jiaxin et al. pointed out that cage-type superconductors can serve as an important carrier for exploring magnetic superconductivity, and called it magnetically intertwined superconductivity.

Project Introduction

The chiral superconducting gap oscillations observed by Yin Jiaxin's team in the KV3Sb5 and CsV3Sb5 superconductors have an oscillation period of 2×2; the three groups of 2×2 scattering peaks in momentum space have different intensities, and the rotation direction from weak to strong can define the chirality of the superconducting gap oscillations.

Figure 1 Schematic diagram of chiral superconducting oscillation in a Kagome superconductor

Through experiments, it was found that the chirality of the superconducting energy gap oscillation can be controlled by an applied external magnetic field to rotate clockwise or counterclockwise. Furthermore, the research team used a superconducting needle tip to realize a superconducting Josephson tunnel junction to detect the local paired electron density and observed the chiral oscillation of the paired electron density of 2×2.

Figure 2 Superconducting gap oscillation and Josephson zero-energy peak oscillation with a period of 2a

Figure 3 Key evidence of 2×2 chiral pairing density wave

Figure 4 Evidence for the remaining Bogoliubov Fermi arc

Figure 5 Evidence chain of magnetic superconducting state of finite momentum electron pairing