In its early days, solid-state physics was thought of as uninteresting by some prominent names such as Pauli: "Die Festkörperphysik ist eine Schmutzphysik" (Solid state physics is dirt physics) and "One shouldn’t wallow in dirt". To Pauli's surprise, perhaps, this field evolved to condensed matter physics which focuses on the study of collective phenomena and complexity. In this colloquium, we tell the dirtiest story of the dirty physics: a historical overview of the study of the effects of inhomogeneities (defects, vacancies, impurities, i.e., dirt) in magnets that are near or at a phase transition. Similar to the evolution of solid-state physics to condensed matter physics, this sub-field of research also evolved into a beautiful and intellectually challenging endeavor. We overview a few key developments: the Harris criterion, the non-perturbative Griffiths effects, and the exotic infinite-randomness (or infinite-dirty) critical phenomena.
Prof. Hoyos obtained his PhD from Campinas State University in 2005 under the supervision of prof. Eduardo Miranda. He then worked as a postdoc at the Missouri S&T University, at the Duke University, and at the National High Magnetic Field Laboratory. Since 2010, he has been a professor at the University of São Paulo. His interests are in the frontier between condensed matter physics of strongly correlated systems and statistical mechanics. In particular, he is a theorist dedicated to the characterization and classification of the effects of inhomogeneities in a plethora of system models for strongly correlated phenomena.