Abstract
We report on the measurement results of the superconducting-ferromagnetic transistors (SFTs). The devices were made at Northwestern University and Hypres (SeeQC), Inc. (Nevirkovets et al., 2014; 2015). SFT is a multiterminal device with the SISFIFS (or SFIFSIS) structure (where S, I, and F denote a superconductor, an insulator, and a ferromagnetic material, respectively) exploiting intense quasiparticle injection in order to modify the nonlinear I-V curve of a superconducting tunnel junction. SFT is capable of providing voltage, current, and power amplification while having good input/output isolation. We characterized the devices using different measurement techniques. We measured S parameters of the single- and double-acceptor devices at frequencies up to 5 MHz. Importantly, we confirmed that the isolation between the input and output of the device is quite good. However, the techniques typically employed to characterize semiconductor devices do not allow for revealing the full potential of our low-resistive SFT devices, especially those having two acceptors. In the latter case, we also tested the devices using the battery-powered current sources with floating grounds. Analyzing double-acceptor I-V curves recorded at different levels of injection currents, for an optimal load, we deduced a small-signal voltage gain of 33 and a power gain of 2.4. We suggest that further improvement of the SFT device parameters is possible in optimized devices, so that the device potentially may serve as a preamplifier for readout of output signals of cryogenic detectors and be useful as an element of other superconductor-based circuits. In addition, we used scanning transmission electron microscopy to identify some problems in the fabrication of the devices without any planarization.
| Original language | English (US) |
|---|---|
| Article number | 9089265 |
| Journal | IEEE Transactions on Applied Superconductivity |
| Volume | 30 |
| Issue number | 7 |
| DOIs | |
| State | Published - Oct 2020 |
Funding
Manuscript received December 20, 2019; revised April 10, 2020; accepted April 27, 2020. Date of publication May 7, 2020; date of current version May 29, 2020. STEM part of this work was supported by the Office of the Director of National Intelligence, Intelligence Advanced Research Project Activity within the C3 program. Sandia National Laboratories is a multi-program laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U. S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the U. S. Government. This article was recommended by Associate Editor Ethan Cho. (Corresponding author: Ivan P. Nevirkovets.) Ivan P. Nevirkovets is with the Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 USA (e-mail: i-nevirkovets@ northwestern.edu).
Keywords
- Josephson effect
- superconducting electronics
- superconducting-ferromagnetic transistor (SFT)
- superconductivity
- tunneling effect
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering