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arXiv · 1610.10045

Isotope effect in superconducting n-doped SrTiO$_3$

A. Stucky·G. Scheerer·Z. Ren·D. Jaccard·J. -M. Poumirol·C. Barreteau·E. Giannini·D. van der Marel
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Abstract

We report the influence on the superconducting critical temperature $T_c$ in doped SrTiO$_3$ of the substitution of the natural $^{16}$O atoms by the heavier isotope $^{18}$O. We observe that for a wide range of doping this substitution causes a strong ($\sim 50 \%$) enhancement of $T_c$. Also the magnetic critical field $H_{c2}$ is increased by a factor $\sim 2$. Such a strong impact on $T_c$ and $H_{c2}$, with a sign opposite to conventional superconductors, is unprecedented. The observed effect could be the consequence of strong coupling of the doped electrons to lattice vibrations (phonons), a notion which finds support in numerous optical and photo-emission studies. The unusually large size of the observed isotope effect supports a recent model for superconductivity in these materials based on strong coupling to the ferroelectric soft modes of SrTiO$_{3}$.

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A. Stucky, G. Scheerer, Z. Ren, D. Jaccard, J. -M. Poumirol, C. Barreteau, E. Giannini, D. van der Marel. 2016-10-31. Isotope effect in superconducting n-doped SrTiO$_3$. https://arxiv.org/abs/1610.10045

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