Exploring tunable magnet/superconductor hybrid quantum systems via spin-polarized low energy electron microscopy

• Applicant: Roberto Lo Conte, Ph.D.
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2022 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 512050965

In recent years the investigation of quantum materials has been experiencing an unprecedented acceleration, mostly due to the promise of applications in the upcoming quantum information technologies. Magnet/superconductor hybrid (MSH) systems are very promising candidates for designing new quantum materials with tunable properties. Rich new physics is expected to emerge at the interface between a superconducting substrate and an ultra-thin magnetic layer hosting non-collinear spin textures. On the one hand, it has been reported that the superconducting state of the substrate can control the magnetic phase established in the ultra-thin magnet. On the other hand, topologically protected electronic states and equal-spin triplets are predicted to be present at the hetero-interface due to the interplay between the non-collinear spin texture and the superconducting phase, allowing for the emergence of topological superconductivity and spin-polarized supercurrents.Here I propose to use low temperature spin-polarized low energy electron microscopy (SPLEEM) to investigate MSH quantum systems. The unique capabilities of SPLEEM will allow the characterization of the full 3-dimentional spin texture in the deposited magnetic thin films and multilayers with nanometer resolution as a function of temperature (below and above the superconducting critical temperature), with the aim of understanding the influence of superconductivity on the stabilized spin textures in the magnetic layers. All this will be possible by exploiting the unique capabilities of the recently installed low temperature SPLEEM at the Lawrence Berkeley National Laboratory in California, which is the only SPLEEM functioning at liquid He temperature and open for access to external users.Two different types of MSH systems will be investigated. Initially, the study will focus on MSH systems where a bulk superconductor is interfaced with magnetic ultra-thin films and multilayers. The goal of this initial phase of the project will be to discover materials systems hosting non-collinear spin textures and how temperature affects their magnetic ground state. Subsequently, I will study more complex systems, where a thin interlayer of a large spin-orbit coupling material will be inserted at the interface of the initial MSH system. The aim is to understand how the properties of the initial MSH system can be tuned by the presence of the large spin-orbit coupling interlayer.

• DFG Programme: Research Grants
• International Connection: USA
• Cooperation Partner: Dr. Andreas Schmid