Properties of Ferromagnetic Josephson Junctions for Memory Applications

Abstract

In this work we give a characterization of the RF effect of memory switching on Nb-Al/AlOx-(Nb)-Pd0.99Fe0.01-Nb Josephson junctions as a function of magnetic field pulse amplitude and duration, alongside with an electrodynamical characterization of such junctions, in comparison with standard Nb-Al/AlOx-Nb tunnel junctions. The use of microwaves to tune the switching parameters of magnetic Josephson junctions is a step in the development of novel addressing schemes aimed at improving the performances of superconducting memories.

Supercurrent in ferromagnetic Josephson junctions with heavy metal interlayers

“…Breakthroughs in materials engineering and nanolithography techniques in the last two decades have enabled the synthesis of artificial heterostructures, where two or more layers are in direct electronic contact, revealing a wealth of new physics at S-F interfaces [1][2][3]. Exploitation of this new physics has led to advances in the emerging field of superspintronics, which offers a new class of highly energy efficient devices, most promisingly cryogenic memory elements based on ferromagnetic Josephson junctions [4][5][6][7][8][9][10][11][12][13].…”

Tuning of Magnetic Activity in Spin-Filter Josephson Junctions Towards Spin-Triplet Transport

“…Of particular interest to this work, Josephson junctions (JJs) with ferromagnetic materials separating two superconductors have been extensively characterized over the last decade. The simultaneous presence of the macroscopic phase coherence of superconductors and the exchange interaction of ferromagnetic materials is indeed of great value in the study of fundamental questions on possible pairing states in superconductors [1,2], demonstrating the presence of spin-polarized triplet supercurrents [3][4][5][6][7][8][9], and for potential applications in a wide range of cutting edge areas, such as spintronics [10,11], memory applications for high performance computing [12][13][14][15][16][17][18] and circuit components such as π shifters and phase qubits [19][20][21][22][23]. A playground where different forms of order can cooperate and interfere is of considerable value for inspiring other fields of physics [1,2].The existing literature focuses mostly on metallic superconductor/ferromagnet/superconductor (SFS) junctions, where the evidence of long-range spin triplet correlations is well established [3][4][5][6][7][8]: in the presence of equalspin Cooper pairs, the magnitude of the critical current I C decays much more slowly with magnetic barrier thickness than expected for standard singlet supercurrents [4,5].…”

Ferromagnetic Josephson Junctions for High Performance Computation

“…Junctions using ferromagnetic insulating barriers as GdN [11], completely falling in the underdamped regime and even showing macroscopic quantum tunneling effects [12] and indication of spin-triplet supercurrents [13], have also shown properties in principle compatible with memory applications. Recent experiments on SIsFS junctions have demonstrated that the switching mechanism can be enhanced by using external RF fields [14,15]. This result is of relevance because it indicates an additional tool to manipulate the memory state more efficiently.…”