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A century ago, helium was liquefied for the first time, and since then, ultra-low temperature refrigeration using liquid helium has been widely used. For example, some large scientific facilities, deep space exploration, materials science, quantum computing and other high-tech fields. However, there is a global shortage of helium, which is indispensable in cryogenic technology, and what is the way to achieve extremely low temperature refrigeration without helium? A joint research team composed of Professor Su Gang of the University of Chinese Academy of Sciences, Dr. Xiang Junsen and Researcher Sun Peijie of the Institute of Physics of the Chinese Academy of Sciences, Researcher Li Wei of the Institute of Theoretical Physics of the Chinese Academy of Sciences, and Associate Professor Jin Wentao of Beijing University of Aeronautics and Astronautics have recently achieved an important breakthrough in the basic research of extremely low temperature refrigeration without liquid helium through years of research, which provides a solution to the problem of helium shortage in China. The results were published in the international academic journal Nature on January 11, Beijing time.
A supersolid state is a condition that occurs at close to absolute zero (0 open, which is minus 27315 degrees Celsius), in the case of a supersolid state, the atoms in the matter appear in a regular arrangement on the one hand, and at the same time can flow "viscously" in between. Since the ultra-solid state was put forward as a theoretical speculation in the 70s of the 20th century, scientists from all over the world have not found reliable experimental evidence for the existence of ultra-solid matter in solid matter. In this study, Chinese researchers discovered for the first time a novel state of matter called "spin supersolid" in a cobalt-based triangular lattice quantum magnetic material, and obtained experimental evidence of its existence. Subsequently, researchers used the material to obtain 94 millicelons, or minus 273, through the process of adiabatic demagnetizationThe extremely low temperature of 056 degrees Celsius realizes the ultra-low temperature refrigeration without liquid helium, and the effect is named "spin supersolid giant magnetic card effect".
Professor Su Gang of the University of Chinese Academy of Sciences introduced that for example, we put the material found this time into the magnetic field and demagnetize it without heat leakage, that is, remove the magnetic field. Slowly, in the process of lowering the magnetic field, the temperature of the material will slowly decrease, and finally it will drop to 94 millikels (minus 273056 degrees Celsius).
It is understood that ultra-low temperature refrigeration is one of the key core technologies that need to be overcome in the field of scientific research in China. This breakthrough in basic research is the first experimental evidence of the existence of ultra-solid state in actual solid materials in the world. The future work goal of the research team is to continue to break through the limit of extremely low temperature, and build a helium-free ultra-low temperature refrigerator in the future. Cryogenic refrigerators can provide an extremely low temperature operating environment close to absolute zero for superconducting quantum computers, for example, and are widely used in cutting-edge technologies such as condensed matter physics, materials science, and deep space exploration.
CCTV reporter Chu Erjia Li Jun).