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@INPROCEEDINGS{Faley:1031848,
author = {Faley, Michael and Vas, J. V. and Lu, P.-H. and
Dunin-Borkowski, R. E.},
title = {{N}ano{SQUID}s with proximity effect nanobridge {J}osephson
junctions and {P}y nanostructures},
reportid = {FZJ-2024-05859},
year = {2024},
abstract = {Nanoscale superconducting quantum interference devices
(nanoSQUIDs) with nanobridge Josephson junctions (nJJs) were
prepared on SiN and SiC membranes for experiments in a
transmission electron microscope (TEM) at temperatures below
10 K. As thin-film materials for the nanobridges, metals Ti
and Nb or nitrides TiN and NbN were combined into 3-layer
heterostructures for adjusting superconducting parameters
through the proximity effect. This allowed to reduce spread
of parameters in ultrathin superconducting films and to fit
operation temperature to the most stable temperature of the
commercial TEM sample holder that was cooled using flow of
liquid helium. The sample holder thermometer was also used
as a heater, allowing the sample temperature to be brought
from 600 K to 5 K and back in a few seconds. The nanoSQUIDs
had a sub-micrometer loop size, which limited the dimensions
of the nJJs to below ~100 nm. Electron beam lithography and
high selectivity reactive ion etching with pure SF6 gas were
used to pattern nJJs with down to 10 nm width that is
comparable to coherence length in thin films of Nb and NbN
and provide a better reproducibility in the case of Nb
functional layer but a better long term stability due to an
enhanced corrosion resistance in the case of NbN layer.
Nanoscale superconducting quantum interference devices
(nanoSQUIDs) with nanobridge Josephson junctions (nJJs) were
prepared at a distance of below 200 nm from the tip of a
cantilever by using a focused ion beam to achieve bulk
nanosculpturing of the substrate. High-resolution TEM
revealed that NbN films on SiN have a columnar structure
while they observe cube-on-cube epitaxial growth on SiC
membranes. Measurements revealed non-hysteretic I(V)
characteristics of the nJJs and nanoSQUIDs, peak-to-peak
quantum oscillations in the V(B)-characteristics of the
nanoSQUIDs with an amplitude of >20 µV and a white noise
spin resolution of approximately 400 μB/√Hz that was
obtained without use of SQUID array preamplifier. Towards
future realization of hybrid superconductor-ferromagnetic
nanostructures for spintronics experiments in TEM, Permalloy
(Py) nanodots and triangles with dimensions down to ~100 nm
were prepared on SiN membranes and studied by Lorentz
microscopy and electron holography TEM methods. These
technologies are promising for the fabrication of
superconducting electronics based on nJJs for operation
inside a TEM.},
month = {Sep},
date = {2024-09-01},
organization = {Applied Superconductivity Conference,
Salt Lake City (USA), 1 Sep 2024 - 6
Sep 2024},
subtyp = {After Call},
cin = {ER-C-1},
cid = {I:(DE-Juel1)ER-C-1-20170209},
pnm = {5351 - Platform for Correlative, In Situ and Operando
Characterization (POF4-535) / 3D MAGiC - Three-dimensional
magnetization textures: Discovery and control on the
nanoscale (856538)},
pid = {G:(DE-HGF)POF4-5351 / G:(EU-Grant)856538},
typ = {PUB:(DE-HGF)6},
url = {https://juser.fz-juelich.de/record/1031848},
}