Static and radio frequency magnetic response of high T _c superconducting quantum interference filters made by ion irradiation

Abstract

Superconducting Quantum Interference Filters (SQIF) are promising devices for Radio-Frequency (RF) detection combining low noise, high sensitivity, large dynamic range and wide-band capabilities. Impressive progress have been made recently in the field, with SQIF based antennas and amplifiers showing interesting properties in the GHz range using the well-established Nb/AlOx technology. The possibility to extend these results to High Temperature Superconductors (HTS) is still open, and different techniques to fabricate HTS SQIFs are competing to make RF devices.We report on the DC and RF response of a High Temperature SQIF fabricated by the ion irradiation technique. It is made of 1000 Superconducting QUantum Interference Devices (SQUIDs) in series, with loop areas randomly distributed between 6 µm 2 and 60 µm 2 . The DC transfer factor is ∼ 450 V T −1 at optimal bias and temperature, and the maximum voltage swing ∼ 2.5 mV . We show that such a SQIF detects RF signals up to 150 MHz. It presents linear characteristics for RF power spanning more than five decades, and non-linearities develop beyond P RF = −35 dBm in our set-up configuration. Second-harmonic generation has been shown to be minimum at the functioning point in the whole range of frequencies. A model has been developed which captures the essential features of the SQIF RF response.

Magnetic Field Characteristics of Multiple Niobium Three-dimensional Nano-bridge Junctions in Parallel

“…Superconducting quantum interference devices (SQUIDs) comprising two Josephson junctions (JJs) in parallel are well-known sensitive magnetic sensors 1–4 . Recently, greater numbers of JJs have been connected into arrays, such as SQUID arrays and superconducting quantum interference filters (SQIFs), to produce more sensitive magnetometers 5–7 , absolute field magnetometers 8–10 , low-noise amplifiers 11–13 , and near-quantum-limit radio-frequency antennas 14–16 . Theoretically, the function of the transfer from the magnetic field signal to voltage improves linearly with the number of JJs 17–19 .…”

Dynamic properties of high-Tc superconducting nano-junctions made with a focused helium ion beam

“…One of them relies on the extreme sensitivity of HTS materials such as YBa 2 Cu 3 O 7 (YBCO) to disorder, which first reduces T c and then makes it insulating. High energy ion irradiation (HEII) have been used to introduce disorder in YBCO thin films through e-beam resist masks with apertures at the nanometric scale (20-40 nm), to make JJ [12][13][14] and arrays [15][16][17] with interesting high frequencies properties, from microwaves to THz ones. Recently, Cybart et al successfully used a Focused Helium Ion Beam (He FIB) to locally disorder YBCO thin films and make JJ 18 .…”

“…While mainly DC properties of HTS JJ made by this technique have been reported to date, the present work aims at exploring their dynamic behavior, by studying the Josephson oscillation linewidth in the tens of GHz frequency range. This characterization, which gives access to the intrinsic noise of the JJ, is essential for high frequency applications of JJ such as mixers and detectors 14,16,17 and to study unconventional superconductivity 31 .…”

Dynamic properties of high-Tc superconducting nano-junctions made with a focused helium ion beam

“…One of them relies on the extreme sensitivity of HTS materials such as YBa 2 Cu 3 O 7 (YBCO) to disorder, which first reduces T c and then makes it insulating. High energy ion irradiation (HEII) have been used to introduce disorder in YBCO thin films through e-beam resist masks with apertures at the nanometric scale (20 -40 nm), to make JJ [11][12][13] and arrays [14][15][16] with interesting high frequencies properties, from microwaves to THz ones. Recently, Cybart et al successfully used a Focused Helium Ion Beam (He FIB) to locally disorder YBCO thin films and make JJ [17].…”

“…While mainly DC properties of HTS JJ made by this technique have been reported to date, the present work aims at exploring their dynamic behavior, by studying the Josephson oscillation linewidth in the tens of GHz frequency range. This characterization, which gives access to the intrinsic noise of the JJ, is essential for high frequency applications of JJ such as mixers and detectors [13,15,16] and to study unconventional superconductivity [25].…”