Superconducting materials can transfer electrical energy without loss, but their applications are limited by the stringent low temperature requirements of superconducting states. Therefore, achieving room temperature superconductivity has become an important goal for scientists, and now they are getting closer and closer to this goal. In the latest issue of Nature, a research team of scientists from the United States and Germany published a paper saying that their experiments confirmed that lanthanum hydride under high pressure has a temperature of 250K (K stands for absolute temperature scale Kelvin, 250K is about -23 ℃). Superconductivity. And 250K is the highest critical temperature confirmed in superconducting materials so far.
In the past century, scientists have been looking for materials that can be superconducting at room temperature. As more and more superconducting materials are discovered, the record of the highest critical temperature is also constantly refreshed, gradually moving towards the goal of room temperature. In 2018, two independent research groups reported almost simultaneously that compressed lanthanum hydride compounds may exhibit superconductivity at higher temperatures, with critical temperature ranges ranging from 215K to 280K. This theoretical prediction caused widespread concern at the time.
This time, researchers from the United States and Germany verified this theoretical prediction through experiments. They used a device called a diamond pressure chamber, using two diamonds to squeeze a small piece of lanthanum sample to convert it to a lanthanum hydride compound-LaH10 at a high pressure of 170 GPa, and then detect it with X-rays Structure and composition. The researchers observed that LaH10 has three characteristics of superconducting materials, such as zero resistance, lower critical temperature under the effect of an applied magnetic field, and isotope effect (a phenomenon in which critical temperature depends on isotope mass), but the sample size is too small to superconduct Another important feature of the material-the Meissner effect (a phenomenon of repulsion of magnetic fields by superconductors) is observed. They said that the three characteristics they have observed can prove that at a temperature of 250K, lanthanum hydride will become a superconducting substance at more than 1 million times the atmospheric pressure of the earth.
250K is the latest record of human high-temperature superconductivity, which is about 50K higher than the previous highest critical temperature. The researchers say this is an encouraging step towards achieving the goal of room temperature superconductivity. In the same period, a review article published in the "Nature" magazine pointed out that this research result shows that scientists may have entered a new stage in the study of superconducting materials, starting from the discovery of superconductors by empirical rules, intuition, or luck, to specific theory Forecasts guide research transition. (Reporter Liu Haiying)
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