Induced ferroelectricity and enhanced superconductivity through B -site doped SrT i1-x Zrx O3

SrTiO3 is an ABO3 perovskite and nearly ferroelectric insulator that becomes one of the most dilute electron-doped superconductors known. While its superconducting mechanism is still under debate, recent studies have shown a strong connection between its incipient ferroelectricity and superconductivity. Here we induce ferroelectricity through the substitution of the perovskite B site with Zr and observe a ferroelectric transition in SrTi1-xZrxO3 for as low as x=0.01. Metallic SrTi1-xZrxO3-δ is formed through oxygen reduction, and resistive upturns indicative of the polar metal phase are observed at low temperatures. Superconductivity is enhanced up to a factor of 2 for optimal doping, and Tc enhancement decreases for higher Zr concentration. We observe a shift in the superconducting domes, as well as the formation of a superconducting dome with respect to ferroelectric substitution. These findings provide evidence in support of superconductivity driven by quantum critical fluctuations and the two-phonon pairing model in SrTiO3.