Beijing, February 29, Tech Daily – Harvard University in the United States has developed a cutting-edge tool for accurately measuring the properties of superconductors, as reported in the latest issue of the journal "Nature." They innovatively integrated quantum sensors into standard pressure-sensing devices, allowing for the direct measurement of the electrical and magnetic properties of pressurized materials.
Hydrogen exhibits peculiar behavior under pressure. Theoretical predictions suggest that this typically gaseous element, under pressures exceeding one million atmospheres, can transform into a metal and even a superconductor. Scientists have been eager to understand superconducting hydrogen-rich compounds (known as hydrides) for potential practical applications, such as magnetic levitation trains and particle detectors. However, existing methods make it challenging to study these materials, let alone accurately measure their properties.
The new tool developed by the Harvard University team not only enables the study of hydride superconductors under high pressure but also allows for imaging their behavior.
The conventional approach to studying hydrides under extreme pressure involves using a diamond anvil cell, a device that compresses a small amount of material between two faces of cut diamonds. To detect when the sample transitions into a superconductive state, researchers typically look for two features: a drop in resistance to zero and repulsion of any nearby magnetic field (known as the Meissner effect).
To apply the necessary pressure, researchers must secure the sample with a gasket to ensure even compression and then enclose the sample in a chamber. However, observing the dual characteristics of superconductive conductivity has proven challenging.
To address this issue, the researchers designed and tested a clever modification: they directly integrated a thin layer of sensors onto the surface of the diamond anvil. These sensors are made from defects naturally occurring in the diamond lattice and are known as nitrogen-vacancy centers. Using these effective quantum sensors, termed nitrogen-vacancy centers, the researchers imaged the region inside the chamber when the sample was pressurized and entered the superconducting phase. To validate their concept, the researchers utilized hydrogenated cerium, a material known to become a superconductor at approximately one million atmospheres.
This new tool not only aids scientists in discovering novel superconducting hydrides but also facilitates easier research on existing superconductive materials.
