A Century of Progress Toward Room-Temperature Superconductivity: Materials Evolution, Mechanistic Insights, and Current Challenges

Abstract

Since the discovery of superconductivity in mercury in 1911, a central objective of the field has been to raise the superconducting transition temperature (Tc) toward room temperature. Over more than a century, this search has progressed through several distinct material paradigms: conventional phonon-mediated superconductors, strongly correlated cuprates and iron-based systems, and, most recently, hydrogen-rich compounds stabilised at megabar pressures. Each class has increased understanding of superconductivity, but each has also exposed a different bottleneck, from the limited transition temperatures of conventional materials to the mechanistic uncertainty of unconventional superconductors and the severe pressure dependence of hydrides. The review argues that the key bottleneck has shifted. The fundamental question is no longer simply whether sufficiently strong pairing can exist, because high-pressure hydrides have already demonstrated near-room-temperature transition temperatures within a largely conventional electron-phonon framework. Instead, the central challenge is the stabilisation, validation and processing of high-Tc phases under realistic conditions. By comparing Tc, pairing mechanism, pressure requirement and materials stability across major superconducting families, this review identifies the current route to room-temperature superconductivity as a materials-stability problem rather than a purely theoretical search for new pairing mechanisms.