Physics Colloquium Featuring Samuele Sanna, University of Bologna

Title: Emergent topological and quantum phases in materials revealed by nuclei and muons

Abstract:

In quantum materials the interplay between different degrees of freedom, such as spin, charge, phonon, orbital…, governs the quantum behavior of matter and promotes fascinating novel quantum phases. Very often, these materials are characterized by the presence of electronic inhomogeneity and/or competition of
different electronic phases on a local scale. The study of these phases requires local probes with a high spatial resolution and well coupled to electric and/or magnetic interaction, such as nuclei and muons.

In this talk, I will present ways in which combined power of muon and nuclear spectroscopies enables discovery of novel quantum phases of matter in both unconventional insulating and metallic materials. As main examples, I will focus on multipolar ordering and bipolaron quasiparticles recently discovered in Os-based spin-orbit entangled Mott-Dirac insulators [1] and the symmetry breaking cascade found in novel topological V-based Kagome superconductors [2], which undergoes charge-ordering and possibly host exotic antiferromagnetic orbital currents.

[1] L. Celiberti et al. Nat. Comm. 15, 2429 (2024); R Cong, et al. Phys. Rev. Mat. 7 (8), 084409
[2] J. Frassineti et al., Phys. Rev. Research 5, L012017 (2023); J.N. Graham, et al. arXiv:2402.11130 (2024)