Phase transition in the cuprates from a magnetic-field-free stiffness meter viewpoint.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31165737.
- Also identified by DOI 10.1038/s41467-019-10480-x and PMC identifier 6549142.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
A method to measure the superconducting (SC) stiffness tensor [Formula: see text], without subjecting the sample to external magnetic field, is applied to La<sub>1.875</sub>Sr<sub>0.125</sub>CuO<sub>4</sub>. The method is based on the London equation [Formula: see text], where J is the current density and A is the vector potential which is applied in the SC state. Using rotor free A and measuring J via the magnetic moment of superconducting rings, [Formula: see text] at T → T<sub>c</sub> is extracted. The technique is sensitive to very small stiffnesses (penetration depths on the order of a few millimeters). The method is applied to two different rings: one with the current running only in the CuO<sub>2</sub> planes, and another where the current must cross planes. We find different transition temperatures for the two rings, namely, there is a temperature range with two-dimensional stiffness. Additional low energy muon spin rotation measurements on the same sample determine the stiffness anisotropy at T < T<sub>c</sub>.