TITLE:
Emergent Magnetism and Symmetry Breaking in Half-Functionalized Silicene from First Principles
AUTHORS:
N’goyé Bré-Junior Kanga, Boris Irie Bi, N’Gbesso Josée Yao, Aboudrame Kone, Lalla Btissam Drissi, Raymond N’Guessan Kre
KEYWORDS:
Silicene, Half-Functionalization, Density Functional Theory (DFT), Spintronics, Ferromagnetism, Antiferromagnetism, Electronic Band Structure
JOURNAL NAME:
Graphene,
Vol.15 No.1,
January
30,
2026
ABSTRACT: The ability to dynamically tune the electronic and magnetic phases of two-dimensional materials is a critical prerequisite for advanced spintronic applications. In this study, we perform first-principles density functional theory (DFT) calculations, utilizing Projector Augmented-Wave (PAW) pseudopotentials, to investigate the structural, electronic, and magnetic properties of half-hydrogenated and half-fluorinated silicene monolayers. Our energetic and structural analyses reveal that single-sided adatom chemisorption selectively breaks the intrinsic sublattice symmetry, inducing significant out-of-plane charge transfer while maintaining the covalent integrity of the underlying silicon framework. Consequently, the pristine zero-gap Dirac semimetal is fundamentally transformed. Indeed, half-hydrogenation yields an indirect-gap semiconductor, whereas half-fluorination results in an indirect-gap semimetal. Crucially, this site-selective functionalization isolates unpaired electrons on the unpassivated silicon sublattices, driving macroscopic magnetic ordering. Spin-polarized calculations determine that the half-hydrogenated configuration stabilizes in a ferromagnetic ground state with a Curie temperature of TC = 30.6 K, driven by the unpassivated Si p-orbitals. Conversely, the half-fluorinated configuration exhibits an antiferromagnetic ground state governed by a collective electronic contribution from both the unpassivated Si and adatom F p-orbitals. These findings establish half-functionalization as a highly effective, non-destructive strategy to engineer symmetry-broken magnetic phases in silicene, offering a tunable platform for silicon-compatible cryogenic spintronics and nanoscale logic devices.