Scientists at CUHK, the world's first to discover!

Tech 2023-07-13 15:23:42 Source: Network

At 11:00 p.m

At 11:00 p.m. on July 12, Beijing time, Nature published the scientific achievement led by Professor Wang Meng's team of Sun Yat-sen University: the first discovery of nickel oxide superconductor at liquid nitrogen temperature.

This is a new High-temperature superconductivity system first discovered by Chinese scientists in the world. It is the second unconventional superconductor material found in the liquid nitrogen temperature zone. It is a breakthrough in the field of basic research "from 0 to 1". It is expected to promote the understanding of High-temperature superconductivity mechanism, make it possible to design and predict High-temperature superconductivity materials, and achieve broader and large-scale industrial applications.

The research team sharpened a sword in three years

In the laboratory of Zheshengtang School of Physics on the south campus of Sun Yat-sen University's Guangzhou campus, Professor Wang Meng's team showed a few centimetres of black bar, which is the "new star" discovered this time - the single crystal sample of High-temperature superconductivity new material La3Ni2O7. This seemingly "plain and unadorned" material rod has condensed the team's years of hard work.

The growth conditions of La3Ni2O7 are extremely harsh, with an average valence state of positive 2.5, deviating from the stable valence state of Ni and a narrow range of oxygen pressure. The research team spent more than two years trying to figure out the growth conditions, "said Professor Wang Meng.

Professor Wang Meng's team of students is operating an optical floating zone furnace

However, new materials may not necessarily bring new breakthroughs. There is no mature theoretical guidance for the research of High-temperature superconductivity, and there is great uncertainty. Since the discovery of copper oxide superconductivity in 1986, scientists have been exploring superconductivity in transition metal compounds such as nickel. However, in the past 40 years of research, there has been no breakthrough in the superconductivity of nickel based oxides.

Huo Mengwu, the co first author of the paper and doctoral candidate of the School of Physics of Sun Yat-sen University, is introducing various materials for team growth

No one knows where the endpoint is. If they know, we can design a path to reach the endpoint, but basic research is unlocking the unknown, and the unknown is full of uncertainty, "Wang Meng said.

Professor Wang Meng guides students

Fortunately, this time, the team succeeded. The team carried out experimental research on La3Ni2O7 single crystal material on the high-pressure experimental research platform of Sun Yat-sen University, South China University of Technology, Institute of Physics of Chinese Academy of Sciences, and the Synchrotron radiation device in Beijing, and soon determined that it was transformed into superconductor under pressure, and the superconducting transformation temperature reached the liquid nitrogen temperature zone, up to 80K (Kelvin).

Professor Wang Meng conducts comprehensive physical property measurement of materials

Received high praise from Nature magazine

Superconducting materials have the special properties of absolute zero resistance, complete Diamagnetism and macroscopic quantum tunneling effect, which have important scientific and application values. Since the discovery, there have been five related Nobel Prizes.

Chinese scientists also won the first prize of the National Natural Science Award twice and the Highest Science and Technology Award once for their breakthroughs in the superconducting field.

In 2008, Japanese scientists found Superconductivity in an iron arsenic based material. Quickly, Chinese scientists synthesized various iron arsenic materials, raising the maximum superconducting temperature of the block to 55K and promoting its application, but failed to enter the liquid nitrogen temperature range.

The mechanism of High-temperature superconductivity has become one of the most important scientific problems in physics in the past 40 years. This time, Chinese scientists have discovered for the first time the superconducting nickel oxide in the liquid nitrogen temperature range, which has received high praise from the reviewers of Nature magazine, believing that it is "of outstanding importance" and "a groundbreaking discovery".

After being published on the research paper preprint platform during the review stage, this discovery quickly received widespread attention and follow-up research from researchers in the field of superconductivity worldwide. Over a month, more than ten related theoretical and experimental works have been published one after another.

It is expected to crack the mechanism of High-temperature superconductivity

"This discovery of High-temperature superconductivity nickel oxide has a positive valence of 2.5, which is beyond traditional expectations. Its electronic structure and magnetic properties are completely different from those of copper oxide. Through comparative research, it is possible to determine the key factors of High-temperature superconductivity and promote scientists to understand the mechanism of High-temperature superconductivity." Professor Wang Meng introduced, "According to the mechanism, it is expected to design and synthesize more new and easier to apply High-temperature superconductivity materials after crossing with computer, AI technology and other disciplines, so as to achieve more extensive applications."

Professor Wang Meng's team held a group meeting

The reporter learned that this work was completed under the leadership of Wang Meng, a professor in the School of Physics of Sun Yat-sen University. Sun Hualei, an associate researcher of the School of Physics of Sun Yat-sen University, and Huo Mengwu, a doctoral candidate, are the co first author of the paper, and Wang Meng and Zhang Guangming, a professor of Tsinghua University, are the co corresponding authors of the paper.

Sun Hualei, the co first author of the paper and the distinguished associate researcher of the School of Physics of Sun Yat-sen University, is conducting an experiment

"Since 2017, Sun Yat-sen University has begun to build a public research platform of the School of Physics, creating first-class conditions for the team's material growth and characterization experiments." Wang Meng said that the neutron spectrometer built by Sun Yat-sen University will also help the team to further study materials and promote the solution of the mechanism.

Huo Mengwu is operating the optical floating zone furnace

The team is already on the way to further exploration. At present, our superconducting materials require a pressure of 14GPa to be achieved, which will limit the research on superconducting mechanisms and widespread applications. The research team is currently working on a key issue and hopes to grow nickel oxide superconductors that can achieve liquid nitrogen temperature superconductivity at atmospheric pressure, "said Wang Meng.

Source: Guangzhou Daily

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