论文标题
竞争配对互动负责在基于化学计量的超导体中，负责大型上部关键领域，cakfe $ _4 $ as $ _4 $
Competing pairing interactions responsible for the large upper critical field in a stoichiometric iron-based superconductor, CaKFe$_4$As$_4$
论文作者
论文摘要
多次超导体的上部临界场是一个重要数量，可以揭示有关超导配对性质的细节。在这里，我们在实验中绘制了化学计量超导体的完整上临界场相图，Cakfe $ _4 $为$ _4 $，在磁场的不同方向和温度下降到4.2k时，最多可达90T。上部临界场非常大，在最低温度下达到接近〜3 $ t_c $的值，各向异性随着温度而大大降低，导致4.2K的各向同性超导性基本上。我们发现，上临界场的温度依赖性可以通过两种波段模型在干净极限的情况下很好地描述，带有带耦合参数，偏爱内部的频带耦合参数。大的Pauli顺磁效应以及浅带的存在与在此干净的超导体中低温下FFLO状态的稳定相一致。
The upper critical field of multiband superconductors is an important quantity that can reveal the details about the nature of the superconducting pairing. Here we experimentally map out the complete upper critical field phase diagram of a stoichiometric superconductor, CaKFe$_4$As$_4$, up to 90T for different orientations of the magnetic field and at temperatures down to 4.2K. The upper critical fields are extremely large, reaching values close to ~3$T_c$ at the lowest temperature, and the anisotropy decreases dramatically with temperature leading to essentially isotropic superconductivity at 4.2K. We find that the temperature dependence of the upper critical field can be well described by a two-band model in the clean limit with band coupling parameters favouring intraband over interband interactions. The large Pauli paramagnetic effects together with the presence of the shallow bands is consistent with the stabilization of an FFLO state at low temperatures in this clean superconductor.
