MAGNETISM AND NANOSPINTRONICS IN SEMICONDUCTOR NANOSTRUCTURES, TOPOLOGICAL MATERIALS 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 in 2D van der Waals (vdW) materials and characteristics of 3D topological insulators (TI) and topological semimetals realized in thin films. We also aim to research 1D TI nanowires, within a project funded by Carl Tryggers foundation. We intend to initiate a new study based on the use of Big Data and machine learning algorithms to characterize the TI phases of these systems. Therefore we are asking for significant resource allocations.
We employ first principles methods based on density functional theory (DFT) calculations carried out with state-of-the-art codes such as: Wien2K, VASP, Siesta, Transiesta, SMEAGOL and NRLMOL. For further analysis we use codes such as Wannier90 and WannierTools.
Specific goals for the coming year (Oct 2023 - Oct 2024) are:
1) To probe valley-polarization effects and quantum transport in vdW heterostructures consisting of 2D materials and magnetic substrates. We will investigate the use of spin-orbit and spin-transfer torque to control the magnetization at the interface.
2) Predictions on 2D antiferromagnets, characterization of exchange interactions.
3) to model spin-dependent transport in quasi 1D NWs and core-shell NW heterostructures of different classes of TIs, topological crystalline insulators and Weyl semimetals. This project is supported by the Carl Trygger Stiftelse grant and involves considerable code development and massive computational work.
These projects will provide crucial theoretical support for Masters thesis projects and new/existing research collaborations with other groups (e.g., A. H. MacDonald at the University of Texas at Austin and M. Pederson at ELPaso). This work is partly supported by the VR grants 2021-04622, with PI C.M. Canali. This work is also part of the activity of the Knowledge Environment (Kunskapsmiljö) “Advanced Materials” recently established at LNU. https://lnu.se/en/meet-linnaeus-university/knowledge-environments/advanced-materials/
Other ongoing projects that will continue in 2023:
4) Continuation of the study on quantum anomalous Hall and axion insulator phases in magnetic thin films and TI heterostructures.
5) 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 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.
Highlight of Recent Research Publication:
1. J. F. Nossa et al., Electric control of spin states in frustrated triangular molecular magnets, Phys. Rev. B 107, 245402 (2023).
2. S. S. Han et al., Reversible Transition of Semiconducting PtSe2 and Metallic PtTe2 for Scalable All-2D Edge-Contacted FETs, under review in Nano Letters, ACS publ.
