Josephson Junctions Containing Antiferromagnetic FeMn and IrMn for Cryogenic Memory Application*

The study of ferromagnetic Josephson junctions for cryogenic memory applications is an area of intense research interest. The prototypical memory device takes the form of an S/F/F’/S spin valve where the two ferromagnetic layers [F, F’] have different switching fields. Switching the relative magnetizations of the two layers between parallel and antiparallel tunes the ground state phase difference across the junction to either 0 or π [1], and corresponds to a bit in a proposed memory cell [2]. It is necessary to design a device where the magnetization of the hard F’ layer is robust within the switching field range of the soft F layer. A traditional method of accomplishing this in MRAM applications is to exchange-bias one of the layers by pinning its magnetization with an adjacent antiferromagnetic layer. To determine if that method can be used in cryogenic memory, we have fabricated Josephson junctions containing FeMn/NiFe and IrMn/NiFe bilayers. We present the results in this poster.

[1] Gingrich E.C., et. al., Nature Physics, 12, 564–567 (2016)
[2] Dayton I.M., et. al., IEEE Magnetics Letters, 9, 3301905 (2018)