Tailoring Topological Phases in Two Dimensional Magnets

Date

Sep 29, 2025

Time

1:30 PM - 2:30 PM

Speaker

Dr. Ritwik Das

Affiliation

School of Physical Sciences, Indian Association for the Cultivation of Science

Language

en

Main Topic

Materialien

Host

Grit Rötzer

Description

In this talk, we shall explore the interplay between symmetry, Coulomb correlations, and spin–orbit coupling in two-dimensional ferromagnets, which provide a versatile platform for realizing Chern insulating phases. The electronic topology in these systems can be tuned by manipulating orientation of magnetic moments as well as electronic correlations offering complementary pathways for topological phase transitions. Reorienting the magnetic moment within the ferromagnetic phase modifies the band topology, while in the correlated regime, increasing electronic interactions encoded in the Hubbard U parameter alter the magnetic ground state, driving a transition between distinct topological phases. We demonstrate that, in the Chern insulating phase, the orientation of magnetic moments at lattice sites serves as a key tuning parameter for the realization of nontrivial topological phases. We show that the Rashba spin-orbit coupling (SOC) induced by broken out-of-plane mirror symmetry together with the intrinsic SOC incorporated in a tight-binding model, captures the rich topological phase diagram of these systems as a function of orientation of magnetic moments. The Mott-insulating phase in the strong correlation limit is modelled by Hubbard-Kanamori (HK) Hamiltonian incorporating spin-orbit coupling. Here onsite energies and hopping parameters, preserving the crystal symmetry are extracted from the first principles density functional theory (DFT) calculations. Exact diagonalization (ED) calculations of the HK Hamiltonian on a two-site cluster are performed to construct the effective magnetic Hamiltonian. We shall discuss the ground-state magnetic properties as a function of correlation strength U and Hund’s coupling JH explored using the ED approach on a 24-sites cluster. References [1] R Das, S Bandyopadhyay, I Dasgupta, Electron. Struct. 6, 025005 (2024) [2] R Das, A and I Dasgupta, arXiv:2502.06686 (2025) [3] R. Das and I. Dasgupta, arXiv:2506.22279 (2025) .

Links

• Seminars at the IFW

Last modified: Sep 23, 2025, 7:37:06 AM