A selection of papers | Chinese scientists discovered and confirmed boson exotic metals for the first time

Elementary particles in the universe can be divided into two types: fermions and bosons. As early as thirty years ago, scientists discovered fermion exotic metals, but the existence of boson exotic metals is a long-standing unsolved problem.

Recently, the team of Academician Li Yanrong, director of the State Key Laboratory of Electronic Thin Films and Integrated Devices of the University of Electronic Science and Technology of China, and James M. Valles Jr. of Brown University, and Academician Xie Xincheng of the School of Physics/Center for Quantum Materials Science of Peking University, successfully broke through the limitations of the fermion system, found and confirmed the boson exotic metal in the high-temperature superconductor for the first time, and conquered the above scientific problems strange metal in a bosonic system) was published on January 12 in the international journal Nature.

This discovery has laid an important scientific foundation for understanding the physical laws of exotic metals in condensed matter physics, revealing the universality of exotic metals, and perfecting the theory of quantum phase transition; it has important theoretical and practical significance for revealing the quantitative effect of dissipation effects on boson quantum coherence, promoting future low-energy superconducting quantum computing and the development of extremely highly sensitive quantum detection technology.

Basic information about the paper

Corresponding Author:

Li Yanrong, Academician of Chinese Academy of Engineering, Director of state key laboratory of electronic thin films and integrated devices of university of electronic science and technology of China

论文标题：Signatures of a strange metal in a bosonic system

Field Direction: Condensed Matter Physics

Source journal: Nature

OJI:10.1038/s41586-021-04239-y

Original link:

https://www.nature.com/articles/s41586-021-04239-y#citeas

Posted: 2022-1-12

Journal Impact Factor: 49.962

JCR partition: Q1

According to the paper, the team found and confirmed boson exotic metals in high-temperature superconductors. So, what exactly is a strange metal? As the name suggests, exotic metals are different from ordinary metals, their resistivity is proportional to temperature, and they exist in copper-based high-temperature superconductors, beyond the framework of Fermi's liquid theory, and are a new state of matter with high quantum entanglement between electrons.

Historically, the study of exotic metals has been mostly in thin films or bulk materials, and usually requires a strong magnetic field to suppress the superconducting state, which limits the singular metal to the fermion system.

Figure | Schematic of the physical image of boson singular metal in a high-temperature superconducting film modulated by a nanocell structure. The blue bubbles represent the Cooper pair, the arrows represent the phase of the Cooper pair, and the waves represent the superconducting fluctuations (Source: Nature)

By accurately constructing a nano-mesh array in a high-temperature superconducting yttrium barium copper-oxygen (YBCO) film, the research team realized the cross-scale regulation of boson coherence, dissipative energy and other physical properties, and found a strange metal state in the critical region of quantum phase transition whose resistance changes linearly with temperature and magnetic field. At the same time, below the superconducting critical temperature, the Hall resistance decreases sharply to zero, and there is an h/2e superconducting quantum magnetoresistance oscillation associated with the Cooper electron pair, proving that the carrier of the system is a boson.

The research team further through scale analysis found that the resistance of boson singular metals is determined by a simple linear addition of temperature and magnetic field, which proves that the resistance in the quantum critical region has nothing to do with the intrinsic energy scale of Hall resistance, and the relationship between satisfying the scale is unchanged, revealing the strange dynamic behavior of bosons in the quantum critical region; establishing a complete phase diagram of boson singular metals; and illustrating the physical image of the dissipation quantum phase transition of the Boson system.

The discovery of boson exotic metals provides a good research platform for revealing the quantitative effect of dissipation effects on boson quantum coherence, so it has fundamental significance. At the same time, this gives people the opportunity to further study the physical nature of exotic metals, which may be the key to driving the next generation of low-power computing devices and extremely high-sensitivity quantum detector devices.

How to further promote boson exotic metal research in the future? The research team said, "In terms of physics, we plan to study boson exotic metals through further experimental means, including transport measurements under strong magnetic fields, thermal transport measurements, photoconductivity measurements, etc., and it is expected to observe more interesting physical phenomena in boson exotic metals." In terms of applications, we have also been working on the preparation of high-temperature superconducting single-photon detectors based on Bose metal states, which is expected to achieve lightweight and compact, highly sensitive high-temperature superconducting single-photon detection prototype devices, and hopes to be applied to defense equipment systems, quantum communications, aerospace and other fields. ”

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