New advances in heterostructure design for spintronic and quantum technologies

by Virginia Greco

A study on hybrid semiconductor-ferromagnetic insulator heterostructures, performed by an international team of researchers including the ICN2 Advanced Electron Nanoscopy Group, has been featured on the cover of the current issue of ACS Applied Materials & Interfaces. This research is relevant to applications in spintronics and emerging quantum technologies.

Semiconductors and ferromagnetic insulators are often combined in heterostructures for spintronic and quantum technologies, in which the first materials – in particular those characterized by narrow direct band gaps – provide high electron mobilities and strong spin-orbit coupling, while the second ones allow increasing electron spin degeneracy, which is crucial for these applications. Large external magnetic fields are normally needed to take advantage of the properties of these structures, but in many cases it would be helpful to avoid applying such external fields. Various researches are ongoing to develop structures integrating materials that meet this goal.

A recent study carried out by researchers from the ICN2 Advanced Electron Nanoscopy Group, led by ICREA Prof. Jordi Arbiol, from the University of Copenhagen and the Microsoft Quantum Materials Lab Copenhagen (Denmark) – with Prof. Peter Krogstrup as corresponding author --, and from the Paul Sherrer Institute (Switzerland), investigates the bicrystal epitaxy of InAs/EuS interfaces, which are unique hybrid heterostructures showing interesting characteristics.

This work, published on the current issue of ACS Applied Materials & Interfaces and featured on its cover, is an important contribution toward the design and synthesis of a defect-free semiconductor-ferromagnetic insulator epitaxial hybrid material for quantum and spintronic applications without external magnetic fields. This research is closely related to another study, recently published on NanoLetters and sharing the main authors, in which the technology here described is applied to the fabrication of hybrid nanowires for spin-based applications, such as a scalable quantum computing.

Reference article:

Yu Liu, Alessandra Luchini, Sara Martí-Sánchez, Christian Koch, Sergej Schuwalow, Sabbir A. Khan, Tomaš Stankevič, Sonia Francoual, Jose R. L. Mardegan, Jonas A. Krieger, Vladimir N. Strocov, Jochen Stahn, Carlos A. F. Vaz, Mahesh Ramakrishnan, Urs Staub, Kim Lefmann, Gabriel Aeppli, Jordi Arbiol and Peter Krogstrup, Coherent Epitaxial Semiconductor–Ferromagnetic Insulator InAs/EuS Interfaces: Band Alignment and Magnetic Structure, ACS Applied Materials & Interfaces 2020, 12, 7, 8780-8787. DOI: 10.1021/acsami.9b15034