Effect of External Magnetic Field on the Co-existence of Superconductivity and Antiferromagnetism in rare Earth Nickle Borocarbides (RNi2B2C)

TL;DR

This study investigates how an external magnetic field influences the coexistence of superconductivity and antiferromagnetism in rare earth nickel borocarbides, using a mean field approach to analyze order parameters and energy gaps.

Contribution

It introduces a theoretical framework to analyze the effects of magnetic fields on coexisting superconducting and antiferromagnetic phases in RNi2B2C compounds, aligning well with experimental data.

Findings

Magnetic field affects superconducting and magnetic order parameters.

Calculated energy gap ratios are close to BCS predictions.

External magnetic field influences the hybridization and order parameters.

Abstract

In this paper we have studied the effect of external magnetic field in the co-existing phase of superconducting and anti-ferromagnetism of rare earth nickel borocarbides. The anti-ferromagnetism in these systems might have originated due to both localized 'f' electrons as well as itinerant electrons which are responsible for conduction. On the other hand, superconductivity is due to spin density wave, arising out of Fermi surface instability. The anti-ferromagnetism order is mostly influenced by hybridization of the 'f' electron with the conduction electron. Here we have obtained the dependence of superconducting energy gap as well as staggered magnetic field on temperature T and energy $\epsilon_k$ in a framework based on mean field Hamiltonian using double time electron Green's function. We have shown in our calculation the effect of external magnetic field on superconducting and anti-ferromagnetic order parameter for $YNi_2B_2C$ in the presence of hybridization. The ratio of the calculated effective gap and $T_C$ is close to BCS value which agrees quite well with experimental results.