Role of charge doping and lattice distortions in codoped Mg_{1-x}(AlLi)_{x}B_2 compounds

TL;DR

This study investigates how charge doping and lattice distortions affect the properties of MgB2 when doped with Al and Li, revealing that lattice deformation significantly influences superconductivity.

Contribution

It demonstrates that lattice deformation, rather than electron doping alone, governs the superconducting properties in Mg_{1-x}(AlLi)_{x}B_2 compounds.

Findings

Li enters the MgB2 structure but less than nominal amount

Superconducting properties scale with Al content, not electron doping

Lattice deformation plays a key role in tuning superconductivity

Abstract

We prepared a series of Mg_{1-x}(AlLi)_{x}B_2 samples with 0≤x≤0.45 in order to compensate with Li the electron doping induced by Al. Structural characterization by means of neutron and X-ray diffraction confirms that Li enters the MgB2 structure even though in an amount less than nominal one. We performed susceptibility, resistivity and specific heat measurements. Vibrational properties were also investigated by means of Raman spectroscopy. We compare these results with those obtained on a homologous series of Mg_{1-x}Al_{x}B_2 samples. The systematic success of scaling the relevant properties with the Al content rather than with the electron doping suggests that lattice deformation plays an important role in tuning the superconducting properties.