Superconductorsthe

Superconductorsthe is not a standard term in physics. This article describes superconductivity and notes that the combined string may reflect a typographic error or a misreading of related terms such as “superconductors.” Superconductors are materials that, when cooled below a characteristic critical temperature, exhibit two defining properties: zero electrical resistance and the expulsion of magnetic fields, known as the Meissner effect.

Historically, superconductivity was discovered in 1911 by Heike Kamerlingh Onnes in mercury at 4.2 kelvin. The theoretical understanding advanced with the BCS theory in 1957, which explained conventional superconductors as arising from electron pairing mediated by lattice vibrations. Materials are categorized as Type I or Type II based on their magnetic response; Type II superconductors can tolerate higher magnetic fields and are more widely used in practical applications. High-temperature superconductors, first discovered in 1986, operate at comparatively higher temperatures but remain less well understood.

Materials and mechanisms vary. Conventional superconductors rely on electron-phonon coupling described by BCS theory. Unconventional superconductors, including many cuprates and iron-based compounds, exhibit superconductivity through mechanisms that are still an active area of research. Some hydrogen-rich materials show superconductivity at very high pressures, approaching ambient temperatures only under extreme conditions.

Applications include powerful magnets for MRI and maglev trains, components in particle accelerators, and superconducting quantum interference devices (SQUIDs) used in sensitive measurements. Challenges remain, such as the need for cooling, material brittleness, and manufacturing costs, which influence widespread deployment.