Magnetism and Nanospintronics in Quantum Materials, Topological Insulators and Molecular Magnets
Abstract
In this project, we aim to study the rich quantum phenomenology in nanostructures of novel quantum materials. Our primary focus is on magnetism and quantum transport in 2D van der Waals (vdW) materials and the characteristics of 3D topological insulators (TIs) and semimetals realized in thin films. Another key objective is to expedite new studies 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, QuantumESPRESSO, 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 (February 2026 - January 2027) are:
1) Studies of Topological Magneto-Electric Effect (TME) will continue and will be supplemented by novel studies of Magneto-Optical Effects, which are presently investigated intensively in experiments (manuscript near completion). We will address some outstanding issues that need to be resolved and the conditions that need to be achieved to realize 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 spintronics 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 of different classes of TIs, topological crystalline insulators and Weyl semimetals. This project involves code development and massive computational work.
6) Magnetic superconductor candidate materials will be investigated together with thesis students.
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) and is supported by the VR grants 2021-04622. 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 TI heterostructures.
2) Theoretical investigation of multiferroic properties of chiral molecular magnets for the realization of controllable molecular qubits. We plan to continue this project by considering other molecules in this class, where the spin-electric coupling is accompanied by a ferroelectric effect, which makes these molecules an example of multiferroic 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.
