An unsolved problem for superconducting electronics is the lack of a scalable cryogenic memory technology. Superconducting memories have scaling limitations and semiconducting memories may not be compatible with the speed and energy-efficiency of superconducting logic. A cryogenic memory technology designed specifically for integration with superconducting devices is required.

Magnetic materials are promising for improved energy efficiencies in memories, but the fringe magnetic field can significantly affect the operation of superconducting electronic devices. In this talk we will explain how this problem might be overcome with the rare-earth or lanthanide nitrides, ferromagnetic semiconductors where the presence of spin and un-quenched orbital magnetic moments allows a much wider control over the magnetic properties than in other materials. Using solid solutions of lanthanide nitrides such as (Gdx,Sm1−x)N we demonstrate independent control of the net-magnetisation and coercive field.

We will present our work on two memory concepts based on the highly tunable magnetic
properties of the lanthanide nitrides. We will show their incorporation into trilayer switchable magnetic dot memory elements, readable by standard Josephson junctions. We will also show our work using the lanthanide nitrides as the barrier layer in magnetic Josephson junctions, towards fast, scalable and low power-dissipation memory devices ready to integrate with superconducting electronics.