Lanthanum superhydride (La4H23) belongs to polyhydrides, a new class of compounds synthesised at pressures approximately a million times greater than atmospheric pressure. The peculiarity of La4H23 is that unlike ordinary metals, its electrical resistance does not decrease with decreasing temperature but increases. This property is usually characteristic of semiconductors and many high-temperature superconductors.
“Observing such unusual behaviour of the new polyhydride, we decided to study the effect of strong pulsed magnetic fields on this compound. The study of the sample our colleagues obtained from Jilin University in a diamond anvil cell led to another interesting discovery,” Skoltech quotes Dmitry Semenok, an employee of the Chinese Center for High Pressure Science and Technology Advanced Research (HPSTAR).
It turned out that in powerful pulsed magnetic fields, the synthesised lanthanum superhydride exhibits a significant negative magnetoresistance which indicates anomalous metal properties of this compound. As a rule, metals are characterised by positive magnetoresistance due to a large length of the electron trajectories in a magnetic field, and negative magnetoresistance is very rare.
“We are still far from understanding all the processes determining the physical properties of superhydrides. However, every year new evidence appears that despite differences in the electron pairing mechanisms, hydrides have much in common with such high-temperature superconductors as cuprates,” Skoltech quotes Dmitry Semenok.
Combining the properties of both conventional and high-temperature superconductors, hydrides act as a link between different the classes of superconducting materials. The scientists plan to continue their studies of different types of superhydrides under strong magnetic fields, paying particular attention to their behaviour, which is atypical for metals.
