Low anisotropy of the upper critical field in a strongly anisotropic layered cuprate Bi2.15Sr1.9CuO6+delta: Evidence for a paramagnetically limited superconductivity
2014 (English)In: Physical Review B, ISSN 2469-9950, Vol. 89, no 21, 214516Article in journal (Refereed) Published
We study angular-dependent magnetoresistance in a low-T-c layered cuprate Bi2.15Sr1.9CuO6+delta. The low Tc similar to 4 K allows complete suppression of superconductivity by modest magnetic fields and facilitates accurate analysis of the upper critical field H-c2. We observe a universal exponential decay of fluctuation conductivity in a broad range of temperatures above Tc and propose a method for extraction of H-c2(T) from the scaling analysis of the fluctuation conductivity at T > T c. Our main result is observation of a surprisingly low H-c2 anisotropy similar to 2, which is much smaller than the effective mass anisotropy of the material similar to 300. We show that the anisotropy is decreasing with increasing field and saturates at a small value when the field reaches the paramagnetic limit. We argue that the dramatic discrepancy of high-field and low-field anisotropies is clear evidence for paramagnetically limited superconductivity.
Place, publisher, year, edition, pages
2014. Vol. 89, no 21, 214516
Research subject Physics
IdentifiersURN: urn:nbn:se:su:diva-106332DOI: 10.1103/PhysRevB.89.214516ISI: 000337943500005OAI: oai:DiVA.org:su-106332DiVA: diva2:736602