The physics of imperfection: from percolation to localization and local moment instabilities

Kedar Damle (TIFR, Mumbai)

Solid state physicists try hard to reduce impurities and imperfections when making crystals of interesting materials. However, impurity effects are not always just a nuisance; sometimes they lead to physics that is interesting in its own right, for example Anderson’s famous discovery of electron localization and Broadbent and Hammersley’s nearly contemporaneous identification of percolation transitions. In this talk, I will review this physics and then describe an interesting connection between a class of localization problems and an unusual percolation phenomenon in the random geometry of maximum-density dimer packings of disordered lattices. Implications of this percolation phenomenon for topological superconductors and frustrated magnets with vacancy disorder will also be discussed.

The talk is based on Bhola & KD arxiv:2311.05634v2 (May2025); Bhola & KD, Phys. Rev. B 114, 105125 (2026); Ansari, Kundu, & KD Phys. Rev. B in press (arXiv:2602.24203); Ansari & KD, Phys. Rev. Lett. 132, 226504 (2024); KD, Phys. Rev. B 105, 235118 (2022); Bhola, Biswas, Islam, KD Phys. Rev. X 12, 021058 (2022); Sanyal, KD, Motrunich, Phys. Rev. Lett. 117, 116806 (2016).

Contact : F. Alet