Imaging the Meissner effect and flux trapping of superconductors under high pressure using N-V centers

Abstract

Pressure is a key parameter for tuning or revealing superconductivity in materials and compounds. Many measurements of superconducting phase transition temperatures have been conducted using diamond anvil cells (DACs), which provide a wide pressure range and enable concomitant microscopic structural characterization of the sample. However, the inherently small sample volumes in DACs complicate the unambiguous detection of the Meissner effect, the hallmark of superconductivity. Recently, the Meissner effect in superconductors within a DAC was successfully demonstrated using diamond nitrogen-vacancy (N-V) widefield magnetometry, a noninvasive optical technique. In this work, we show that N-V magnetometry can also map superconductivity with micrometer resolution. We apply this technique to a microcrystal of HgBa2Ca2Cu3O8+δ (Hg-1223) mercury-based cuprate superconductor under 4 GPa of pressure. The method is capable of mapping the magnetic field expulsion and the critical temperature Tc of the sample, allowing to determine its heterogeneities. Flux pinning zones are identified through flux trapping maps. This approach could enable detailed investigations of superconductivity of a broad range of materials under high-pressure conditions.

Source-reported materials — not catalogue approval

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