Guterding Daniel, Jeschke Harald O, Mazin I I, Glasbrenner J K, Bascones E, Valentí Roser
Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany.
Code 6393, Naval Research Laboratory, Washington, District of Columbia 20375, USA.
Phys Rev Lett. 2017 Jan 6;118(1):017204. doi: 10.1103/PhysRevLett.118.017204. Epub 2017 Jan 5.
Unconventional superconductivity in iron pnictides and chalcogenides has been suggested to be controlled by the interplay of low-energy antiferromagnetic spin fluctuations and the particular topology of the Fermi surface in these materials. Based on this premise, one would also expect the large class of isostructural and isoelectronic iron germanide compounds to be good superconductors. As a matter of fact, they, however, superconduct at very low temperatures or not at all. In this work we establish that superconductivity in iron germanides is suppressed by strong ferromagnetic tendencies, which surprisingly do not originate from changes in bond angles or bond distances with respect to iron pnictides and chalcogenides, but are due to changes in the electronic structure in a wide range of energies happening upon substitution of atom species (As by Ge and the corresponding spacer cations). Our results indicate that superconductivity in iron-based materials may not always be fully understood based on d or d-p model Hamiltonians only.
铁基氮化物和硫族化合物中的非常规超导性被认为是由低能反铁磁自旋涨落与这些材料中费米面的特殊拓扑结构之间的相互作用所控制。基于这一前提，人们也会预期一大类同结构和等电子的铁锗化合物是良好的超导体。然而事实上，它们要么在极低温度下超导，要么根本不超导。在这项工作中，我们确定铁锗化合物中的超导性被强铁磁倾向所抑制，令人惊讶的是，这种倾向并非源于相对于铁基氮化物和硫族化合物的键角或键距的变化，而是由于在原子种类（用锗取代砷以及相应的间隔阳离子）取代时在很宽能量范围内发生的电子结构变化。我们的结果表明，仅基于d或d - p模型哈密顿量可能无法完全理解铁基材料中的超导性。
