guest ::
| Home > Publications database > Ab initio investigation of topological magnetism in two-dimensional van der Waals heterostructures |
| Home > Publications database > Ab initio investigation of topological magnetism in two-dimensional van der Waals heterostructures |
| Book/Dissertation / PhD Thesis | FZJ-2025-01804 |
2025
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
Jülich
ISBN: 978-3-95806-808-7
This record in other databases:
Please use a persistent id in citations: doi:10.34734/FZJ-2025-01804
Abstract: Magnetism in two-dimensional (2D) van der Walls (vdW) materials is a rapidly evolving field in condensed matter physics and materials science, marked by intriguing discoveries and potential applications. Unlike traditional three-dimensional materials, 2D vdW materials are characterized by their ultra-thin, often single-layer, structure leading to unique magnetic properties triggered by proximity-effects, which are facilitated by the underlying vdW gap. Such properties are not only fundamental for understanding the physics of low-dimensional systems but also hold immense promise for the development of advanced technologies in data storage, spintronics, and quantum computing. Building on the foundational understanding of magnetism in 2D materials, this thesis dives deeper into the specific case of CrTe2 and CrSBr. Based on a multiscale modelling approach that combines first-principles calculations and a Heisenberg model supplied with ab-initio parameters, we report a strong magnetoelastic coupling in a free-standing monolayer of CrTe2. We demonstrate that different crystal structures of a single CrTe2 give rise to non-collinear magnetism through magnetic frustration and the emergence of the Dzyaloshinskii-Moriya interaction (DMI). Utilizing atomistic spin relaxation, we perform a detailed investigation of the complex magnetic properties pertaining to this 2D material impacted by the presence of various types of structural distortions akin to charge density waves. Also, we demonstrate that interfacing a CrTe2 layer with various Te-based layers enables the control of the magnetic exchange and Dzyaloshinskii-Moriya interactions as well as the magnetic anisotropy energy of the whole heterobilayer, and thereby the emergence of topological magnetic phases such as skyrmions and antiferromagnetic N´eel merons. The latter are novel particles in the world of topological magnetism since they arise in a frustrated N´eel magnetic environment and manifest as multiples of intertwined hexamer-textures. Our findings pave a promising road for proximity-induced engineering of both ferromagnetic and long-sought antiferromagnetic chiral objects in the very same 2D material, which is appealing for new information technology devices employing quantum materials. Moreover, we demonstrate the all-electric switching of the topological nature of individual magnetic objects emerging in 2D vdW heterobilayers. We show that an external electric field modifies the vdW gap between CrTe2 and (Rh, Ti)Te2 layers and alters the underlying magnetic interactions. This enables switching between ferromagnetic skyrmions and meron pairs in the CrTe2/RhTe2 heterobilayer while it enhances the stability of frustrated antiferromagnetic merons in the CrTe2/TiTe2 heterobilayer. We envision that the electrical engineering of distinct topological magnetic solitons in a single device could pave the way for novel energy-efficient mechanisms to store and transmit information with applications in spintronics. Finally, via machine learning concepts we integrated linear spin wave theory (LSWT) with activelearning sampling to develop a Kalman Filter Adversarial Bayesian Optimization (KFABO) algorithm. This algorithm excels at managing highly noisy experimental spectra of 2D bulk CrSBr, aiming to map the experimentally extracted magnon spectrum with minimal sampling points and iterations. Additionally, the KFABO algorithm is designed to accurately extract magnetic parameters from inelastic neutron scattering data, significantly enhancing the efficiency and accuracy of experimental measurements.
; 
|
The record appears in these collections: |
PDF