Ferroelectricity-induced multiorbital odd-frequency superconductivity in SrTiO\(_3\)

• Published in: arXiv.org
• Main Authors: Kanasugi, Shota, Kuzmanovski, Dushko, Balatsky, Alexander V, Yanase, Youichi
• Format: Paper
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 25.06.2020
• Subjects: Classification; Correlation; Critical point; Ferroelectric materials; Ferroelectricity; Order parameters; Parity; Superconductivity
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2006.14181

We demonstrate that SrTiO\(_3\) can be a platform for observing the bulk odd-frequency superconducting state owing to the multiorbital/multiband nature. We consider a three-orbital tight-binding model for SrTiO\(_3\) in the vicinity of a ferroelectric critical point. Assuming an intraorbital spin-singlet \(s\)-wave superconducting order parameter, it is shown that the odd-frequency pair correlations are generated due to the intrinsic LS coupling which leads to the local orbital mixing. Furthermore, we show the existence of additional odd-frequency pair correlations in the ferroelectric phase, which is induced by an odd-parity orbital hybridization term proportional to the ferroelectric order parameter. We also perform a group theoretical classification of the odd-frequency pair amplitudes based on the fermionic and space group symmetries of the system. The classification table enables us to predict dominant components of the odd-frequency pair correlations based on the symmetry of the normal state Hamiltonian that we take into account. Furthermore, we show that experimental signatures of the odd-parity orbital hybridization, which is an essential ingredient for the ferroelectricity-induced odd-frequency pair correlations, can be observed in the spectral functions and density of states.