Superconducting circuits carry current without electrical resistance. However, their usefulness also depends on controlling the quantum phase, which describes the collective rhythm of paired electrons. Magnetism can alter this phase, offering a potential solution for building superconducting memory and quantum circuits with fewer external magnetic controls. However, combining magnetism with superconductivity is challenging, because the magnetic alignment of electron spins can disrupt the Cooper pairs that carry a supercurrent. Semiconductors could help researchers study and control this interaction because their electrical properties can be adjusted with a gate voltage. Building such devices, however, requires exceptionally clean interfaces between materials with very different properties.
A research team from the University of Tokyo and New York University has developed a hybrid semiconductor device that brings these capabilities together. Led by Hirotaka Hara and Lukas Baker, with supervision by Masaaki Tanaka, Javad Shabani and Le Duc Anh, the team grew a layer of superconducting aluminum above a semiconductor (indium arsenide) channel layer and a magnetic semiconductor (iron-doped gallium antimonide) layer, below it. The layers were grown in an ultrahigh vacuum without exposing to air, to preserve clean interfaces. Electron microscopy confirmed an atomically sharp and clean interface between the aluminum and the semiconductor.
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