Anisotropy of electron momentum distribution in Bi$_2$Sr$_2$CaCu$_2$O$_(8+d)$ superconductor studied by positron annihilation technique

TL;DR

This study investigates the anisotropic electron momentum distribution in Bi-2212 high-temperature superconductor using positron annihilation, revealing directional differences and temperature-dependent changes near the superconducting transition.

Contribution

It provides new insights into the anisotropic electron momentum distribution and its temperature dependence in Bi-2212 superconductors using positron annihilation techniques.

Findings

Electron momentum distribution is larger along the c-axis than the a-b plane.

A step-like increase in the S-parameter occurs between 92 K and 116 K.

Anisotropic behavior persists across the temperature range studied.

Abstract

The temperature dependent (30 K to 300 K) Doppler broadening of the positron annihilated g-radiation (DBPAR) measurement has been carried out on single crystalline Bi-2212 high Tc superconducting sample along two different crystallographic orientations. It has been observed that throughout the temperature range the electron momentum distribution has a relatively large value along the crystallographic c-axis than a-b plane. The temperature dependent DBPARL analysis shows a step like increase of S-parameter at the temperature region 92 K to 116 K.