Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 81: Superconductivity: Properties and Electronic Structure
TT 81.12: Vortrag
Donnerstag, 3. April 2014, 12:30–12:45, HSZ 201
Suppression of superconductivity in a single layer of Pb on Si(111) by insertion of a single layer of Ag — •Hirofumi Oka1, Augusto A. Leon Vanegas1, Agnieszka Stepniak1, Michael Caminale1, Dirk Sander1, and Jürgen Kirschner1,2 — 1MPI Halle — 2MLU Halle-Wittenberg
A recent study indicates that even a single atomic layer of Pb on Si(111) is superconducting with a critical temperature of 1.83 K [1].
Here, we investigate effect of insertion of a single layer of Ag on superconductivity (SC) in a single layer of Pb on Si(111) using a 3He-cooled STM with a vector magnetic field.
Ag was deposited onto the clean 7×7-Si(111) surface held at 770 K, leading to a formation of a single layer of Ag on Si(111).
Subsequently Pb atoms were evaporated at 300 K, followed by annealing at 560 K for 1 min.
Our STM study reveals that the Pb/Ag/Si(111) surface has a well-ordered atomic structure.
Most of the surface shows a stripe pattern indicative of a √3×√7 structure and small areas show a √3×√3 structure.
STS measurements on the Pb/Ag/Si(111) surface show almost the same differential-conductance spectrum with temperature (0.38–6.0 K) or magnetic field (up to 3 T).
We do not observe a SC gap in spectroscopy.
Our results indicate that the insertion of a Ag layer suppresses SC in a single layer of Pb on Si(111).
We speculate that the Ag insertion modifies the bonding situation between Pb and Si, which has been reported to play a crucial role for the SC of the single Pb layer on Si(111) [2].
Zhang et al., Nat. Phys. 6, 104 (2010)
Noffsinger and Cohen, Sol. State Comm. 151, 421 (2011)