NanoSQUIDs from YBa $_2$ Cu $_3$ O $_7$ /SrTiO $_3$ superlattices with bicrystal grain boundary Josephson junctionsNanoSQUIDs from YBa$_2$Cu$_3$O$_7$/SrTiO$_3$ superlattices with bicrystal grain boundary Josephson junctions

Juhn‐Jong Lin, Julian Linek, R. Kleiner +1 more

We report on the fabrication and characterization of nanopatterned dc SQUIDs with grain boundary Josephson junctions based on heteroepitaxially grown YBa $_2$ Cu $_3$ O $_7$ (YBCO)/ SiTrO $_3$ (STO) superlattices on STO bicrystal substrates. Nanopatterning is performed by Ga focused-ion-beam milling. The electric transport properties and thermal white flux noise of superlattice nanoSQUIDs are comparable to single layer YBCO devices on STO bicrystals. However, we find that the superlattice nanoSQUIDs have more than an order of magnitude smaller low-frequency excess flux noise, with root-mean-square spectral density $S_Φ^{1/2}\sim 5-6\,μΦ_0/\sqrt{\rm Hz}$ at 1 Hz ( $Φ_0$ is the magnetic flux quantum). We attribute this improvement to an improved microstructure at the grain boundaries forming the Josephson junctions in our YBCO nanoSQUDs.We report on the fabrication and characterization of nanopatterned dc SQUIDs with grain boundary Josephson junctions based on heteroepitaxially grown YBa$_2$Cu$_3$O$_7$ (YBCO)/ SiTrO$_3$ (STO) superlattices on STO bicrystal substrates. Nanopatterning is performed by Ga focused-ion-beam milling. The electric transport properties and thermal white flux noise of superlattice nanoSQUIDs are comparable to single layer YBCO devices on STO bicrystals. However, we find that the superlattice nanoSQUIDs have more than an order of magnitude smaller low-frequency excess flux noise, with root-mean-square spectral density $S_Φ^{1/2}\sim 5-6\,μΦ_0/\sqrt{\rm Hz}$ at 1 Hz ($Φ_0$ is the magnetic flux quantum). We attribute this improvement to an improved microstructure at the grain boundaries forming the Josephson junctions in our YBCO nanoSQUDs.

arXiv:2007.11046Jul 21, 20200 citations

Josephson oscillation linewidth of ion-irradiated YBa 2 Cu 3 O 7 junctions

A Sharafiev, M. Malnou, C. Feuillet-Palma +4 more

Abstract We report on the noise properties of ion-irradiated YBa 2 Cu 3 O 7 Josephson junctions. This work aims at investigating the linewidth of the Josephson oscillation with a detector response experiment at ≃132 GHz. Experimental results are compared with a simple analytical model based on the Likharev–Semenov equation and the de Gennes dirty limit approximation. We show that the main source of low-frequency fluctuations in these junctions is the broadband Johnson noise and that the excess 1 f noise contribution does not prevail in the temperature range of interest, as reported in some other types of high- T c superconducting Josephson junctions. Finally, we discuss the interest of ion-irradiated junctions to implement frequency-tunable oscillators consisting of synchronized arrays of Josephson junctions.Abstract We report on the noise properties of ion-irradiated YBa 2 Cu 3 O 7 Josephson junctions. This work aims at investigating the linewidth of the Josephson oscillation with a detector response experiment at ≃132 GHz. Experimental results are compared with a simple analytical model based on the Likharev–Semenov equation and the de Gennes dirty limit approximation. We show that the main source of low-frequency fluctuations in these junctions is the broadband Johnson noise and that the excess 1 f noise contribution does not prevail in the temperature range of interest, as reported in some other types of high- T c superconducting Josephson junctions. Finally, we discuss the interest of ion-irradiated junctions to implement frequency-tunable oscillators consisting of synchronized arrays of Josephson junctions.

arXiv:1603.08466Superconductor Science and TechnologyMay 17, 201610 citations

Noise characteristics of series connected superconducting Josephson contacts

I. M. Dmitrenko, Н. И. Иванов, I. I. Iurchenko

Журнал технической физикиOct 1, 19760 citations

Zero-point fluctuation and noise phenomena in Josephson junctions

JIANG WANG-YE, Fu-sui Liu

Journal of Low Temperature PhysicsJan 1, 19860 citations

NanoSQUIDs from YBa

_2

_3

_7

/SrTiO

_3

superlattices with bicrystal grain boundary Josephson junctions

We report on the fabrication and characterization of nanopatterned dc SQUIDs with grain boundary Josephson junctions based on heteroepitaxially grown YBa

_2

_3

_7

(YBCO)/ SiTrO

_3

(STO) superlattices on STO bicrystal substrates. Nanopatterning is performed by Ga focused-ion-beam milling. The electric transport properties and thermal white flux noise of superlattice nanoSQUIDs are comparable to single layer YBCO devices on STO bicrystals. However, we find that the superlattice nanoSQUIDs have more than an order of magnitude smaller low-frequency excess flux noise, with root-mean-square spectral density

S_Φ^{1/2}\sim 5-6\,μΦ_0/\sqrt{\rm Hz}

at 1 Hz (

Φ_0

is the magnetic flux quantum). We attribute this improvement to an improved microstructure at the grain boundaries forming the Josephson junctions in our YBCO nanoSQUDs.