Huge congratulations to Shrestha Dutta on our latest paper, just published in Physical Review B!

In the field of two-dimensional (2D) spintronics, defect engineering of transition metal dichalcogenides (TMDCs) routinely produces local magnetic moments. However, itinerant half-metallic ferromagnetism has remained a significant challenge, with experimental realizations frequently yielding paramagnetic insulators instead of the predicted half-metals.

Lead author Shrestha Dutta rigorously resolves this paradox for vacancy-doped monolayer 1T-TiS₂. Her work demonstrates that the insulator-to-half-metal transition is governed fundamentally by the universal geometric percolation of the defect network, extending frameworks previously established for 3D diluted magnetic semiconductors into the 2D limit.

Key highlights of the study include:

• The Percolation Threshold: Utilizing density functional theory (DFT) combined with finite-size scaling on large-scale tight-binding lattices, we identify that robust half-metallicity—featuring 100% spin polarization and a 1.0 eV minority-spin gap—emerges exclusively at a critical vacancy concentration of ~12.5%.
• A Defined Functional Window: We map a highly specific operational window ($11% \leq x \leq 15%$). This window is bounded by subcritical Anderson localization at lower densities and a geometric jamming instability that fragments the conducting network at densities exceeding 20%.
• Universality Class: The extracted Fisher exponent of $\tau = 2.09 \pm 0.03$ confirms that this electronic phase transition belongs strictly to the 2D percolation universality class.

This research establishes geometric connectivity as a quantitative design principle for defect-engineered van der Waals materials, shifting the focus from simple defect density to network topology. Congratulations to Shrestha on this exceptional computational physics milestone. I invite colleagues and researchers in condensed matter physics to read the full analytical methodology in our paper.

Read the Paper:

• Phys Rev B
• arXiv

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