Extreme high-field superconductivity in thin Re films
Extreme high-field superconductivity in thin Re films
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DOI：
10.1103/physrevb.103.024504
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发表时间：
2020-10
影响因子：
3.7
通讯作者：
F. Womack;D. Young;D. Browne;G. Catelani;J. Jiang;E. I. Meletis;P. Adams
中科院分区：
文献类型：
--
作者：
F. Womack;D. Young;D. Browne;G. Catelani;J. Jiang;E. I. Meletis;P. Adams
通过磁输运和隧道态密度测量，我们研究了无序稀土薄膜的高场超导性质。厚度在9~3 nm范围内的薄膜具有$\ensuremath{\sim}0.2\phantom{\rule{4pt}{0ex}}\mathrm{k}\mathrm{\ensuremath{\Omega}}$到$\ensuremath{\sim}1\phantom{\rule{4pt}{0ex}}\mathrm{k}\mathrm{\ensuremath{\Omega}}$的正常态方阻，相应的转变温度在6~3K范围内，隧道谱与中等耦合的BCS超导体的隧道谱一致。尽管具有这些不起眼的超导特性，但薄膜表现出极高的上临界场。我们估计它们的零温度${H}_{c2}$是泡利极限的两倍以上。事实上，在6纳米的样品中，估计的约化临界场${H}_{c2}/{T}_{c}\ensuremath{\sim}5.6\phantom{\rule{0.28em}{0ex}}\mathrm{T}/\mathrm{K}$是所有元素超导体中最高的。虽然薄膜的方阻远低于量子电阻${R}_{q}=h/4{e}^{2}$，但它们的${H}_{c2}$‘S接近强无序超导体的理论上限。
We report the high-field superconducting properties of thin, disordered Re films via magnetotransport and tunneling density of states measurements. Films with thicknesses in the range of 9 to 3 nm had normal-state sheet resistances of $\ensuremath{\sim}0.2\phantom{\rule{4pt}{0ex}}\mathrm{k}\mathrm{\ensuremath{\Omega}}$ to $\ensuremath{\sim}1\phantom{\rule{4pt}{0ex}}\mathrm{k}\mathrm{\ensuremath{\Omega}}$ and corresponding transition temperatures in the range of 6 to 3 K. Tunneling spectra were consistent with those of a moderate coupling BCS superconductor. Notwithstanding these unremarkable superconducting properties, the films exhibited an extraordinarily high upper critical field. We estimate their zero temperature ${H}_{c2}$ to be more than twice the Pauli limit. Indeed, in 6-nm samples the estimated reduced critical field ${H}_{c2}/{T}_{c}\ensuremath{\sim}5.6\phantom{\rule{0.28em}{0ex}}\mathrm{T}/\mathrm{K}$ is among the highest reported for any elemental superconductor. Although the sheet resistances of the films were well below the quantum resistance ${R}_{Q}=h/4{e}^{2}$, their ${H}_{c2}$'s approached the theoretical upper limit of a strongly disordered superconductor for which ${k}_{F}\ensuremath{\ell}\ensuremath{\sim}1$.