Zuned Ahmed | Searcharxiv

arXiv2026

Lattice Reconstruction and Orbital Hybridization Suppress Magnetism in TaCo$_2$Te$_2$

Structural reconstruction in low-dimensional quantum materials can strongly modify electronic symmetry and magnetic stability through orbital hybridization. Here, we investigate the interplay between lattice reconstruction, electronic structure, and magnetic instability in the layered van der Waals compound TaCo$_2$Te$_2$ using scanning tunneling microscopy and spectroscopy (STM/STS), non-contact atomic force microscopy (nc-AFM), angle-resolved photoemission spectroscopy (ARPES), and density functional theory (DFT). While nc-AFM resolves a distorted hexagonal Te surface lattice, STM/STS reveal a pronounced square-like electronic symmetry that does not directly follow the atomic structure. ARPES further shows a strongly anisotropic Fermi surface and reconstructed low-energy states. Spatially resolved spectroscopy and orbital-projected DFT demonstrate that the bias-dependent STM contrast does not arise from a simple reversal between occupied and unoccupied states, but from the energy-integrated local density of states dominated by electronic states exhibiting opposite spatial contrast at selected energies. DFT calculations further show that reconstruction suppresses the magnetic instability present in the undistorted structure, stabilizing a nonmagnetic ground state through enhanced orbital hybridization. These results establish TaCo$_2$Te$_2$ as a model system in which lattice reconstruction reorganizes electronic symmetry and suppresses magnetism, highlighting structural reconstruction as a route for controlling correlated and magnetic phases in low-dimensional quantum materials.

cond-mat.mtrl-sci↗

arXiv2017

Engineering Multiple Topological Phases in Nanoscale Van der Waals Heterostructures: Realisation of $α$-Antimonene

Van der Waals heterostructures have recently been identified as providing many opportunities to create new two-dimensional materials, and in particular to produce materials with topologically interesting states. Here we show that it is possible to create such heterostructures with multiple topological phases in a single nanoscale island. We discuss their growth within the framework of diffusion-limited aggregation, the formation of moiré patterns due to the differing crystallographies of the materials comprising the heterostructure, and the potential to engineer both the electronic structure as well as local variations of topological order. In particular we show that it is possible to build islands which include both the hexagonal $β$- and rectangular $α$-forms of antimonene, on top of the topological insulator $α$-bismuthene. This is the first experimental realisation of $α$-antimonene, and we show that it is a topologically non-trivial material in the quantum spin Hall class.

cond-mat.mtrl-sci↗