Phonon-mediated electron attraction in SrTiO$_3$ via the generalized Fr\"ohlich and deformation potential mechanisms

Christopher J. N. Coveney; Norm M. Tubman; Chih-En Hsu; Andres Montoya-Castillo; Marina R. Filip; Jeffrey B. Neaton; Zhenglu Li; Vojtech Vlcek; Antonios M. Alvertis

arXiv · 2501.17230

Phonon-mediated electron attraction in SrTiO$_3$ via the generalized Fr\"ohlich and deformation potential mechanisms

Christopher J. N. Coveney·Norm M. Tubman·Chih-En Hsu·Andres Montoya-Castillo·Marina R. Filip·Jeffrey B. Neaton·Zhenglu Li·Vojtech Vlcek·Antonios M. Alvertis

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Abstract

Superconductivity in doped SrTiO$_3$ was discovered in 1964, the first superconducting transition observed in a doped semiconductor. However, the mechanism of electron pairing in SrTiO$_3$ remains a subject of debate. By developing a theoretical framework to incorporate dynamical lattice screening in the electronic Coulomb interactions of semiconductors and insulators, we demonstrate analytically that linear long-range coupling of electrons to multiple longitudinal optical phonons, described by a generalized Fr\"ohlich mechanism, can result in superconductivity in SrTiO$_3$. Moreover, by combining our theory with first-principles calculations, we reveal an additional attractive interaction between electrons in SrTiO$_3$ due to the deformation potential mechanism, arising from the mixed ionic-covalent character of the Ti-O bond. Our results may have implications for the emergence of phonon-mediated electron attraction and superconductivity in a broad range of materials.

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Christopher J. N. Coveney, Norm M. Tubman, Chih-En Hsu, Andres Montoya-Castillo, Marina R. Filip, Jeffrey B. Neaton, Zhenglu Li, Vojtech Vlcek, Antonios M. Alvertis. 2025-01-28. Phonon-mediated electron attraction in SrTiO$_3$ via the generalized Fr\"ohlich and deformation potential mechanisms. https://arxiv.org/abs/2501.17230

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