Dear Colleagues,

Superconductors, as a class of unusual materials, exhibit unique behaviors, such as zero resistance, and have greatly practical applications. Therefore, the research into superconductors has attracted widespread attention, especially in the fields of condensed matter physics, chemistry, and materials science. In previous research, mercury was observed to show superconductivity at 4.2 K, opening the door to finding superconductors. Subsequently, the conventional superconductor MgB₂, described by the Bardeen–Cooper–Schrieffer (BCS) theory, was synthesized and had a significantly high-temperature (high-T_c) superconductivity of 39 K at ambient pressure, which motivates researchers to discover higher-T_c superconductors. Meanwhile, theoretical predictions and materials design also play a crucial role in accelerating the discovery of emerging superconductors. Since elemental metallic hydrogen is predicted to be potential high-T_c superconductor because of its high Debye temperature and strong electron–phonon coupling, investigation into the superconductivity of hydrogen has been a research hotspot. However, the extremely high metallization pressure remains a challenge. Recently, numerous binary or ternary high-T_c hydrides with lower metallization pressures and compelling hydrogen structures, including cagelike, pentagraphenelike, or tubelike motifs, have been proposed by means of chemical precompression and advanced structure search approaches, such as CALYPSO. In particular, compressed covalent sulfur hydrides and clathrate superhydrides of alkaline earth and rare earth metals are predicted to have remarkably high-T_c superconductivity, and they not only provide guidance for experiment synthesis but have also been successfully validated. Furthermore, the search for potential candidates for high-T_c materials is still underway. As a consequence, emerging superconducting materials with desirable properties are increasing in importance in the public opinion.

The goal of this Special Issue titled “High Temperature Superconductors” is to offer frontier advances in the study fields of novel excellent superconductive materials by revealing the relationship between superconductivity, structures, and electronic, electrical, etc., properties of materials. Authors are invited to contribute to the Special Issue with articles presenting exciting theoretical and experimental progress.

Dr. Shoutao Zhang
Dr. Bo Gao
Dr. Yuhao Fu
Guest Editors

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• high-temperature superconductivity
• hydrides
• emerging superconductors
• materials simulations
• first-principle calculations