

- Andreev Reflection in Superfluid He-3: A Probe for Quantum Turbulence
Bradley et al., Annual Review of Condensed Matter Physics Vol. 8: 407-430 (2017) - Operating Nanobeams in a Quantum Fluid
Bradley et al., Nature Scientific Reports 7, 4876 (2017) - Single Quantum Level Electron Turnstile
D.M.T. Van Zanten et al., Phys. Rev. Lett. 116 166801 (2016) - Topological Superconductivity and High Chern Numbers in 2D Ferromagnetic Shiba Lattices
J. Röntynen, T. Ojanen, Phys. Rev. Lett. 114 236803, (2015) - Squeezing of Quantum Noise of Motion in a Micromechanical Resonator
J.-M. Pirkkalainen et al., Phys. Rev. Lett 115, 24 (2015) - Direct-current superconducting quantum interference devices for the readout of metallic magnetic calorimeters
S. Kempf, A. Ferring, A. Fleischmann, C. Enss, Supercond. Sci. Technol. 28 , 045008 (2015)
Structural and electrical properties of ultrathin niobium nitride films grown by atomic layer deposition.
S Linzen, M Ziegler, O V Astafiev, M Schmelz, U Hübner, M Diegel, E IlWe studied and optimised the properties of ultrathin superconducting niobium nitride films fabricated with a plasma-enhanced atomic layer deposition (PEALD) process. By adjusting process parameters, the chemical embedding of undesired oxygen into the films was minimised and a film structure consisting of mainly polycrystalline niobium nitride with a small fraction of amorphous niobium oxide and niobium oxo-nitrides were formed. For this composition a critical temperature of 13.8 K and critical current densities of 7 × 106 A cm–2 at 4.2 K were measured on 40 nm thick films. A fundamental correlation between these superconducting properties and the crystal lattice size of the cubic δ-niobium-nitride grains were found. Moreover, the film thickness variation between 40 and 2 nm exhibits a pronounced change of the electrical conductivity at room temperature and reveals a superconductor–insulator-transition in the vicinity of 3 nm film thickness at low temperatures. The thicker films with resistances up to 5 kΩ per square in the normal state turn to the superconducting one at low temperatures. The perfect thickness control and film homogeneity of the PEALD growth make such films extremely promising candidates for developing novel devices on the coherent quantum phase slip effect.
Superconductor Science and Technology, Vol. 30, (2017) 035010
doi: http://dx.doi.org/10.1088/1361-6668/aa572a