Universal superconducting and magnetic properties of the (CaLa)(BaLa)CuO system: a MuSR investigation

TL;DR

This MuSR study of the (CaLa)(BaLa)CuO system reveals its universal superconducting and magnetic properties, confirming the Uemura relation, microscopic phase separation, and the gradual emergence of magnetic fields below T_c.

Contribution

The paper provides new insights into high-temperature superconductivity by demonstrating the system's adherence to the Uemura relation and revealing microscopic phase separation and magnetic field development.

Findings

Uemura relation is more accurately followed by CLBLCO.

T_g and T_c are governed by the same energy scale.

Magnetic fields appear gradually without moment size change.

Abstract

The (Ca_xLa_(1-x))(Ba_(1.75-x)La_(0.25+x))Cu_(3)O_(y) system is ideal for testing theories of high temperature superconductivity, since nearly the full range of doping is controlled by y, and T_(c)^max is continuously controlled by x, with minimal structural changes. We investigate this system with both transverse and longitudinal field MuSR. This allows us to re-examine the Uemura relation, the nature of the spontaneous magnetic fields below T_(c), and the relation between their appearance temperature T_(g) and T_(c)^max . Our major findings are: (I) the Uemura relation is respected by CLBLCO more adequately than by other cuprates, (II) T_(g) and T_(c) are controlled by the same energy scale, (III) the phase separation between hole poor and hole rich regions is a microscopic one, and (IV) spontaneous magnetic fields appear gradually with no moment size evolution.