A Grain Boundary Josephson Junction that Supported Many Careers and Led to Applications with Impact
- PDF / 1,972,213 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 6 Downloads / 184 Views
ORIGINAL PAPER
A Grain Boundary Josephson Junction that Supported Many Careers and Led to Applications with Impact Catherine Patricia Foley 1 & Simon K. H. Lam 1 & Jia Du 1 & E. E. Mitchell 1 & Jeina Lazar 1 & Wendy Purches 1 & Shane Keenan 1 & Marcel Bick 1 & David Clark 1 & Keith Leslie 1 Received: 7 September 2020 / Accepted: 24 September 2020 # Crown 2020
Abstract CSIRO is the Australian national science agency and has been working in superconducting electronics since the 1970s. With the discovery of high-temperature superconductivity in 1986, CSIRO supported a team of researchers to work on YBa2Cu3O7-x (YBCO) step-edge Josephson junctions. This junction technology is the basis of many different HTS devices and sensors. The CSIRO team used these devices in a range of systems for many different applications. This paper briefly reports on the development of the HTS YBCO step-edge junction formed on MgO. It also presents several systems developed with a focus on the most successful commercial system so far called LANDTEM™. This system is used for mineral exploration and has been successful in supporting the delineation and discovery of many billions of dollars of ore bodies. Over a 30-year period, the Josephson junction has been the basis of research for the CSIRO superconductivity team and provided all the team members with rich and fulfilling careers. Keywords HTS Josephson Junction . SQUID . Magnetometer . Gradiometer . YBCO
1 Introduction The discovery of high temperature superconductors and the YBCO material in 1987 led to a new research direction for a team in CSIRO. Working with John Macfarlane and Nick Savvides, the team grew YBCO thin films using an unbalanced magnetron sputtering system and made a very simple SQUID which was placed into a rudimentary flux locked loop [1]. Figure 1 shows a photo of this SQUID and its ac bias current response to applied magnetic fields. From this humble start, the team evolved this research to a point where a Josephson junction technology based on MgO step-edge junctions has enabled a wide range of applications from magnetometry to microwave and terahertz (THz) mixers and detectors described below. This approach to fabrication of Josephson junctions in HTS materials has reached a level of development that can now place many thousands of junctions on a single chip [2] and has levels of reproducibility and
* Catherine Patricia Foley [email protected] 1
CSIRO, P.O. Box 218, Lindfield, NSW 2070, Australia
robustness [3] along with the implementation of the HTS system on compact and portable electric cryocoolers [4] that opens the door to potential wider commercialisation. This short paper covers the development of this type of Josephson junction, a brief review of its properties and several applications. We then focus on the impact of LANDTEM, a commercial system developed to detect deep conducting ore bodies will follow, completing with the story of one team member’s meeting Brian Josephson in Cambridge on the 30th anniversary of his winning the Nobel Prize in Physic
Data Loading...
