24 March 2011 Emergence of superconductivity on a SrTiO3 surface by electric-field charge accumulation
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Proceedings Volume 7940, Oxide-based Materials and Devices II; 79400Q (2011) https://doi.org/10.1117/12.879922
Event: SPIE OPTO, 2011, San Francisco, California, United States
We briefly review principles and main features of an electric double layer transistor (EDLT) as well as electric field induced superconductivity in SrTiO3. EDLT is a field-effect transistor that employs an electrolyte as a gate dielectric. An electric double layer between a semiconductor and the electrolyte attains much higher breakdown field than the maximum of a solid gate dielectric, resulting in high density charge accumulation up to 1014cm-2. That density is sufficient for inducing new physical phases, such as superconductivity and ferromagnetism, on various oxide systems. We employed a surface of a SrTiO3 single crystal as a semiconductor channel. We have demonstrated insulator-tosuperconductor transition by electric field-effect without chemical doping. Charge carrier density was linearly increased from zero to 1014 cm-2 with increasing gate bias to 3.5 V. Superconducting critical parameters, such as critical temperature Tc, critical magnetic field Hc, and critical current density Jc were examined as a function of carrier density by varying gate bias. Tc was almost constant as a function of the carrier density, contrasting to bell-shaped dependence of Hc and Jc. Temperature dependence of I-V curve shows the BKT-type transition, which indicates two-dimensional superconductivity in the electric field induced superconductivity.
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K. Ueno, K. Ueno, S. Nakamura, S. Nakamura, H. Shimotani, H. Shimotani, T. Nojima, T. Nojima, Y. Iwasa, Y. Iwasa, M. Kawasaki, M. Kawasaki, "Emergence of superconductivity on a SrTiO3 surface by electric-field charge accumulation", Proc. SPIE 7940, Oxide-based Materials and Devices II, 79400Q (24 March 2011); doi: 10.1117/12.879922; https://doi.org/10.1117/12.879922

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