The presence of magnetic ions was first believed to be detrimental to superconductivity. However, unconventional superconductivity has been widely induced by doping or applying external pressure in magnetic systems such as heavy fermion, cuprate and iron-based superconductors in which magnetic fluctuations are suggested to serve as the pairing glue for Cooper pairs. The discovery of superconductivity in the magnetic compounds CrAs and MnP under high pressures has further expanded this family of superconductors and provided new platforms for investigating the interplay between magnetism and superconductivity. CrAs and MnP represent the first superconductors among the transition metal Cr- and Mn-based compounds in which the electronic states near the Fermi level are dominated by Cr/Mn 3d electrons. Shortly after their discovery, new types of Cr-based quasi-one-dimensional superconductors A2Cr3As3 and ACr3As3 (A [Formula: see text] K, Rb, Cs or Na) were discovered at ambient pressure. The close proximity of superconductivity to magnetic instability in these systems suggests that spin fluctuations may play crucial roles in mediating the Cooper pairing. In this article we review the basic physical properties of these novel superconductors and the progress achieved in recent studies.

中文翻译：

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铬基和锰基超导体的进展：关键问题回顾

磁性离子的存在首先被认为对超导性有害。然而，通过在磁性系统中掺杂或施加外部压力，如重费米子、铜酸盐和铁基超导体，非常规超导性已被广泛诱导，其中磁波动被建议用作库珀对的配对胶。在高压下磁性化合物 CrAs 和 MnP 中超导性的发现进一步扩展了这一超导体家族，并为研究磁性和超导性之间的相互作用提供了新的平台。CrAs 和 MnP 是过渡金属 Cr 和 Mn 基化合物中的第一种超导体，其中费米能级附近的电子态由 Cr/Mn 3d 电子主导。在他们发现后不久，在常压下发现了新型 Cr 基准一维超导体 A2Cr3As3 和 ACr3As3（A [公式：见正文] K、Rb、Cs 或 Na）。这些系统中超导性与磁不稳定性的接近表明自旋波动可能在介导 Cooper 配对中起关键作用。在本文中，我们回顾了这些新型超导体的基本物理特性以及近期研究取得的进展。