Quantum Magnetic Properties and Metal‐to‐Insulator Transition in Chemically Doped Calcium Ruthenate Perovskite

Ruthenates provide a comprehensive platform to study a plethora of novel properties, such as quantum magnetism, superconductivity, and magnetic fluctuation mediated metal–insulator transition (MIT). Herein, an overview of quantum mechanical phenomenology in calcium ruthenium oxide with varying compositions is provided. While the stoichiometric composition of CaRuO3 exhibits non‐fermi liquid (FL) behavior with quasi‐criticality, chemically doped compounds depict prominent signatures of quantum magnetic fluctuations at low temperature that in some cases are argued to mediate in metal–insulator transition. In the case of cobalt‐doped CaRuO3, an unusual continuum fluctuation is found to persist deep inside the glassy phase of the material. These observations reflect the richness of the ruthenate research platform in the study of quantum magnetic phenomena of fundamental importance. Ruthenates provide a rich platform to study novel quantum magnetic properties of strongly correlated electrons systems. While stoichiometric CaRuO3 is known to manifest non‐FL state, chemical substitutions of Ru‐ion by Ir and Co‐ions unravel highly dynamic correlated spin states that tend to coincide with metal–insulator transition (MIT) as a function of substitution coefficient. The figure shows dispersive behavior in insulating Ca(Ru0.8Co0.2)O3.