Superconducting anisotropy in the electron-doped high-T$_{c}$ superconductors Pr$_{2-x}$Ce$_{x}$CuO$_{4-y}$

TL;DR

This study measures the superconducting anisotropy in electron-doped PCCO, revealing highly anisotropic upper critical fields and comparing these properties with hole-doped cuprates and Fe-based superconductors, providing insights into unconventional superconductivity.

Contribution

It provides detailed measurements of anisotropic critical fields and related parameters in PCCO, highlighting similarities with hole-doped cuprates and differences from Fe-based superconductors.

Findings

Hc2(T) is highly anisotropic at low temperatures.

Hc2(0) for H parallel to c is below the Pauli limit.

PCCO's anisotropic properties resemble hole-doped cuprates more than Fe-based superconductors.

Abstract

We report superconducting anisotropy measurements in the electron-doped high-$T_{c}$ superconductors (HTSCs) Pr$_{2-x}$Ce$_{x}$CuO$_{4-y}$ (PCCO, $x$ = 0.15 and 0.17) with applied magnetic field ($H_{0}$) up to 28 T. Our results show that the upper critical field [$H_{c2}(T)$] is highly anisotropic, and as temperature $T$ $\rightarrow$ 0 the value of it at $H_{0}$ $\parallel$ $c$ [$H_{c2,\parallel c}$(0)] is far less than the Pauli limit, which is very different from that at $H_{0}$ $\perp$ $c$. The $H_{c2}(0)$ character along with the evaluated zero $T$ coherence length $[\xi_{ab(c)}(0)]$ and penetration depth $[\lambda_{ab(c)}(0)]$ is compared with those of the hole-doped cuprate HTSCs and typical Fe-based superconductors. We find that the low temperature anisotropic character of PCCO is rather similar to that of hole-doped cuprate HTSCs, but apparently larger than that of typical Fe-based superconductors. This study also proves a new sensitive probe of detecting rich properties of unconventional superconductors with the use of the resonant frequency of a NMR probe circuit.