Coleman Piers, Komijani Yashar, König Elio J
Center for Materials Theory, Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854-8019, USA.
Department of Physics, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom.
Phys Rev Lett. 2020 Aug 14;125(7):077001. doi: 10.1103/PhysRevLett.125.077001.
A central idea in strongly correlated systems is that doping a Mott insulator leads to a superconductor by transforming the resonating valence bonds (RVBs) into spin-singlet Cooper pairs. Here, we argue that a spin-triplet RVB (tRVB) state, driven by spatially, or orbitally anisotropic ferromagnetic interactions can provide the parent state for triplet superconductivity. We apply this idea to the iron-based superconductors, arguing that strong on site Hund's interactions develop intra-atomic tRVBs between the t_{2g} orbitals. On doping, the presence of two iron atoms per unit cell allows these interorbital triplets to coherently delocalize onto the Fermi surface, forming a fully gapped triplet superconductor. This mechanism gives rise to a unique staggered structure of on site pair correlations, detectable as an alternating π phase shift in a scanning Josephson tunneling microscope.
强关联系统中的一个核心观点是，对莫特绝缘体进行掺杂会通过将共振价键（RVBs）转变为自旋单重态库珀对而导致超导。在此，我们认为由空间或轨道各向异性铁磁相互作用驱动的自旋三重态RVB（tRVB）态可为三重态超导提供母态。我们将这一观点应用于铁基超导体，认为强在位洪德相互作用会在t₂g轨道之间形成原子内tRVB。掺杂时，每个晶胞中有两个铁原子，这使得这些轨道间三重态能够相干地离域到费米面上，形成一个完全能隙的三重态超导体。这种机制会产生在位配对关联的独特交错结构，在扫描约瑟夫森隧道显微镜中可检测为交替的π相移。
