NbTi: a nontrivial puzzle for the conventional theory of superconductivity

Alessio Cucciari; Dionisia Naddeo; Simone Di Cataldo; Lilia Boeri

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arXiv · 2403.15196

NbTi: a nontrivial puzzle for the conventional theory of superconductivity

Alessio Cucciari·Dionisia Naddeo·Simone Di Cataldo·Lilia Boeri

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Abstract

We present the first $ab$-$initio$ study of superconductivity in NbTi, the workhorse for many applications. Despite its apparent simplicity, NbTi turns out to be a major challenge for computational superconductivity. In fact, anharmonic effects are crucial to obtain dynamically stable phonons for the ordered bcc phase, unstable at the harmonic level, and beyond-Morel Anderson effects in the Coulomb interaction reduce the Tc by more than 20%. Lattice disorder causes an additional large discrepancy in $T_c$ compared to experiment. Our results imply that a quantitative description of technologically-relevant superconductors requires methodological developments beyond the current standards.

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Alessio Cucciari, Dionisia Naddeo, Simone Di Cataldo, Lilia Boeri. 2024-03-22. NbTi: a nontrivial puzzle for the conventional theory of superconductivity. https://arxiv.org/abs/2403.15196

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