What is it about?
The "easiness" with which electrons can run through materials, and especially materials of limited dimensions, is crucial for future development of energy-efficient and fast spintronics (a supplement to electronics). It may also have great perspectives in quantum computing. Such "easiness" is denoted "electron mobility". In this paper, we present a route for production of high-mobility (2-dimensional) interfaces between the abundant materials γ-Al₂O₃ and SrTiO₃. In addition, we discuss how "pulling out" oxygen atoms from SrTiO₃, creating oxygen vacancies, before during and after depositing γ-Al₂O₃ on top, using high energetic laser pulses, temperature, and low pressure can affect the electron mobility of the interfaces. We also relate the result of 4 different growth protocols to the oxygen vacancy generation mechanisms, to improve the understanding of how to grow such interfaces reproducibly.
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Why is it important?
During the last decade, no-one has beat the current record of high-mobility SrTiO₃-based interfaces. This is likely because it is a non-trivial material structure to grow, why it is important to shed some light upon the growth mechanisms. Since SrTiO₃-based interfaces host a large amount of interesting physical properties, incl. 2-dimensionality, superconductivity, magnetism, and spin-orbit coupling (connection between the fundamental spin of a particle and its orbital motion), such interfaces have huge potential in future energy-efficient spintronics (a supplement to electronics), and quantum technologies. High-mobility is an important part in enabling this.
Perspectives
In addition to writing a publication with a group of co-authors who I have great respect of on a professional and personal level, I strongly hope that this paper will enable other research groups globally to grow γ-Al₂O₃/SrTiO₃ with high mobility, as the properties in this interface combines many of the same properties found in the better-known LaAlO₃/SrTiO₃ interface with high-mobility. Therefore, this interface may pave the way for future technologies with higher energy-efficiency, logic density, and potentially quantum computational properties.
Thor Hvid-Olsen
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This page is a summary of: Leveraging high fluence and low pressure for pulsed laser deposition of high-mobility γ-Al2O3/SrTiO3 heterostructure growth, Journal of Applied Physics, September 2025, American Institute of Physics,
DOI: 10.1063/5.0278792.
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