Enhancing superconductivity in SrTiO 3 films with strain

• Published in: Science advances Vol. 5; no. 4; p. eaaw0120
• Main Authors: Ahadi, Kaveh, Galletti, Luca, Li, Yuntian, Salmani-Rezaie, Salva, Wu, Wangzhou, Stemmer, Susanne
• Format: Journal Article
• Language: English
• Published: United States 05.04.2019
• ISSN: 2375-2548; 2375-2548
• DOI: 10.1126/sciadv.aaw0120

A doubling of the superconducting transition temperature occurs in strained SrTiO 3 films, which are known to become ferroelectric. The nature of superconductivity in SrTiO 3 , the first oxide superconductor to be discovered, remains a subject of intense debate several decades after its discovery. SrTiO 3 is also an incipient ferroelectric, and several recent theoretical studies have suggested that the two properties may be linked. To investigate whether such a connection exists, we grew strained, epitaxial SrTiO 3 films, which are known to undergo a ferroelectric transition. We show that, for a range of carrier densities, the superconducting transition temperature is enhanced by up to a factor of two compared to unstrained films grown under the same conditions. Moreover, for these films, superconductivity emerges from a resistive state. We discuss the localization behavior in the context of proximity to ferroelectricity. The results point to new opportunities to enhance superconducting transition temperatures in oxide materials.