Bulletin of the American Physical Society
APS March Meeting 2018
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session S14: Topological Materials - Transport
11:15 AM–2:15 PM,
Thursday, March 8, 2018
LACC Room: 304B
Sponsoring Unit: DMP
Chair: Lian Li, West Virginia Univ
Abstract: S14.00012 : The Stiffnessometer - a Magnetic-Field-Free Superconducting Stiffness Meter, Reveals Two Critical Temperatures in LSCO.
1:51 PM–2:03 PM
We have developed a new method to measure superconducting stiffness ρs without subjecting the sample to magnetic field or putting leads . The method is based on the London equation J=-ρsA, where J is the current density and A is the vector potential. Using rotor free A and measuring J via the magnetic moment of a superconducting ring, we determine ρs. The technique is sensitive to very small stiffness, which translates to penetration depth on the order of 1 mm. Naturally, the method does not suffer from demagnetization factor complications or the presence of vortices. Therefore, the absolute value of the stiffness is obtained. We apply this method to two different La1.875Sr0.125CuO4 rings: one with the current running only in the CuO2 planes, and another where the current must cross between planes. We find different Tc for the two rings. The stiffnessometer results are compared with the Low Energy μSR (LEM) measurements on the same sample. We show that the stiffnessometer can measure stiffness where LEM, and in fact all other techniques, fail. This leads to new conclusions regarding cuprates phase transition.
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