In December 2000, the Japanese team of Professor Jun Akimitsu announced in the scientific journal Nature that the compound MgB2 is superconducting below 40 K (-233°C). This discovery is quite surprising: this compound had been known for dozens of years, was available in the shops and on the shelves of many laboratories. However, it was the first time that its superconducting properties were proved…
This was all the more surprising since a systematic study of borides had been conducted in the 60s, in quest of superconductors: MgB2 had just been ignored. Many theoretical and experimental studies have been conducted to explain the origin of superconductivity in this forgotten compound with a simple crystallographic structure. Scientists soon concluded that it was a conventional mechanism, following the BCS model, with however an originality boosting the temperature where superconductivity appears: two electron families coexist in this material, with different properties, and form different pairs depending on the atom vibrations (this pairing is the key of BCS theory). It took less than two years to solve this problem, thus opening new theoretical ways. Today, research on this compound mainly focuses on its possible applications.
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