Carrier Transport in Magnesium Diboride: Role of Nano-inclusions

TL;DR

This study investigates how nano-inclusions in MgB2 influence thermal transport, revealing their impact on phonon and electron scattering, and highlighting a small but clear superconducting transition signature.

Contribution

It provides new insights into the role of MgO nano-inclusions in modifying thermal conductivity and scattering mechanisms in MgB2, especially near Tc and room temperature.

Findings

Nano-inclusions cause a clear Tc signature due to phononic conduction.

MgO defects strongly scatter charge carriers and phonons near Tc.

Nanoparticles induce a crossover from ballistic to diffusive phonon transport.

Abstract

Anisotropic-gap and two-band effects smear out the superconducting transition (Tc) in literature reported thermal conductivity of MgB2, where large electronic contributions also suppress anomaly-manifestation in their negligible phononic-parts. Present thermal transport results on scarcely explored specimens featuring nano-inclusions exhibit a small but clear Tc-signature, traced to relatively appreciable phononic conduction, and its dominant electronic-scattering. The self-formed MgO as extended defects strongly scatter the charge carriers and minutely the phonons with their longer-mean-free-path near Tc. Conversely, near room temperature, the shorter-dominant-wavelength phonon's transport is hugely affected by these nanoparticles, undergoing ballistic to diffusive crossover and eventually entering the Ioffe-Regel mobility threshold regime.