Khaydukov Yury, Pütter Sabine, Guasco Laura, Morari Roman, Kim Gideok, Keller Thomas, Sidorenko Anatolie, Keimer Bernhard
Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany.
Max Planck Society Outstation at the Heinz Maier-Leibnitz Zentrum (MLZ), D-85748 Garching, Germany.
Beilstein J Nanotechnol. 2020 Aug 21;11:1254-1263. doi: 10.3762/bjnano.11.109. eCollection 2020.
We have investigated the structural, magnetic and superconduction properties of [Nb(1.5 nm)/Fe()] superlattices deposited on a thick Nb(50 nm) layer. Our investigation showed that the Nb(50 nm) layer grows epitaxially at 800 °C on the AlO(1-102) substrate. Samples grown at this condition possess a high residual resistivity ratio of 15-20. By using neutron reflectometry we show that Fe/Nb superlattices with 4 nm form a depth-modulated FeNb alloy with concentration of iron varying between 60% and 90%. This alloy has weak ferromagnetic properties. The proximity of this weak ferromagnetic layer to a thick superconductor leads to an intermediate phase that is characterized by a suppressed but still finite resistance of structure in a temperature interval of about 1 K below the superconducting transition of thick Nb. By increasing the thickness of the Fe layer to = 4 nm the intermediate phase disappears. We attribute the intermediate state to proximity induced non-homogeneous superconductivity in the structure.
我们研究了沉积在厚50nm Nb层上的[Nb(1.5nm)/Fe()]超晶格的结构、磁性和超导特性。我们的研究表明，50nm的Nb层在800°C时在AlO(1-102)衬底上外延生长。在此条件下生长的样品具有15至20的高剩余电阻率比。通过中子反射测量，我们表明4nm的Fe/Nb超晶格形成了一种深度调制的FeNb合金，铁的浓度在60%至90%之间变化。这种合金具有弱铁磁特性。这种弱铁磁层与厚超导体的接近导致了一个中间相，其特征是在厚Nb超导转变温度以下约1K的温度区间内，结构的电阻受到抑制但仍有限。通过将Fe层厚度增加到 = 4nm，中间相消失。我们将中间态归因于结构中邻近诱导的非均匀超导性。
