Magnetic 'Super Lenses' Advance Superhydride Superconductor Research

An international research team has achieved a significant breakthrough in studying superhydrides, a class of promising superconductors. Researchers successfully analyzed lanthanum superhydrides under extreme pressure using nuclear magnetic resonance (NMR) spectroscopy for the first time. This methodological advancement provides new insights into these materials.

Superconductors conduct electricity without resistance below a critical temperature. Most known superconductors require cooling below 140 Kelvin (minus 133 degrees Celsius). Scientists are seeking materials that superconduct at higher temperatures. Superhydrides are hydrogen-rich compounds that exhibit superconductivity near room temperature under immense pressure. They currently hold the record for the highest critical transition temperature observed.

The team compressed samples in diamond anvil cells to pressures exceeding one million atmospheres. This process creates conditions similar to those found inside planets. The challenge lies in the tiny sample size, which demands high experimental precision. Researchers used microstructured conductive ring elements, called Lenz lenses, to focus high-frequency fields for NMR spectroscopy. This focusing amplified the fields within the sample volume.

Dr. Florian Bärtl from the Dresden High Magnetic Field Laboratory (HLD) at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) explained the precision required. The high-frequency fields were focused on an area tens of micrometers wide. This area is smaller than a human hair. The Lenz lenses amplified the signal, making meaningful NMR data accessible for superhydrides. These measurements offer direct insights into the atomic properties of the materials.

The team previously investigated these materials using pulsed high-field magnets at the HLD. They measured electrical resistance to determine the maximum field strengths at which superconductivity remains stable. Combining NMR investigations under high pressure with resistance measurements at high magnetic fields provides a comprehensive understanding. This research aims to understand superconductivity's physical mechanisms in hydrogen-rich materials. This knowledge could drive the development of new energy-efficient technologies.

The research was a collaboration with high-pressure experts from the Center for High Pressure Science & Technology Advanced Research (HPSTAR) in Beijing. Dr. Dmitrii Semenok highlighted the crucial role of HLD's high-field facilities and expertise. The findings were published in the journal *Advanced Science*.