Magnetism and Nanospintronics in Quantum Materials, Topological Insulators and Molecular Magnets
Abstract
In this project, we aim to study rich quantum phenomenology in nanostructures of novel quantum materials. Our primary focus is on magnetism and quantum transport in two-dimensional (2D) van der Waals (vdW) materials and characteristics of 3D topological insulators and semimetals realised in thin films. Another key objective is to research topological nanowires and aim to initiate a new study based on the use of machine learning in condensed matter physics. We employ first principles methods based on density functional theory (DFT) calculations using state-of-the-art codes such as: VASP, Wien2K, Siesta, Transiesta, SMEAGOL and NRLMOL. Moreover, Wannier90 and WannierTools packages are used to compute topological properties.
Specific aims and objectives for the coming year (Jan 2025 - Jan 2026) are:
1) Continued investigation of the Topological Magneto-electric Effect (TME). We will address some outstanding issues that need to be resolved and the conditions that need to be achieved to realise a robust TME in real materials. A second general purpose is to explore the use of the TME in radically new 2D tunable vdW-barrier spintronic devices that rely on the interaction and electronic transport across the vdW gap innate to 2D heterojunctions.
2) Quantum transport in topological matter and vdW heterostructures consisting of pristine 2Ds and magnetic substrates.
3) Non-linear Hall effect, surface reconstructions and associated phenomenon in magnetic TIs.
4) To investigate the use of spin-orbit torque and spin-transfer torque in controlling magnetization in 2D magnets and vdW heterostructures.
5) To model spin-dependent transport in quasi 1D NWs and core-shell NWs of different classes of TIs, topological crystalline insulators and Weyl semimetals. This project involves code development and massive computational work.
6) InAs surfaces and their electrostatic potentials for usage in solar cell applications.
These projects will provide crucial theoretical support for Masters/PhD thesis projects, postdoctoral projects and strengthening research collaborations with other groups (e.g., A. MacDonald at the University of Texas at Austin and Mark Pederson at El Paso). This work is partly supported by the VR grants 2021-04622 with C. M. Canali as PI. Our work is also part of the Knowledge Environment (Kunskapsmiljö) “Advanced Materials” established at LNU. https://lnu.se/en/meet-linnaeus-university/knowledge-environments/advanced-materials/
Other ongoing projects that will continue:
1) Continuation of the study on quantum anomalous Hall and axion insulator phases in magnetic thin films and TII heterostructures.
2) Theoretical investigation of multiferroic properties of chiral molecular magnets for the realization of controllable molecular qbits. We plan to continue this project by considering other molecules in this class, where the spin-electric coupling is accom-panied by a ferroelectric effect, which makes these molecules an example of multifer-roic molecular magnetic qubits. A second goal of the project is the theoretical study on how the spin-electric coupling is affected by attaching these molecules to metallic leads in molecular junctions, or by positioning them on surfaces, so that they can be addressed in quantum transport experiments.
