SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK.
Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada.
Nat Commun. 2018 Jul 4;9(1):2602. doi: 10.1038/s41467-018-04909-y.
In many high temperature superconductors, small orthorhombic distortions of the lattice structure result in surprisingly large symmetry breaking of the electronic states and macroscopic properties, an effect often referred to as nematicity. To directly study the impact of symmetry-breaking lattice distortions on the electronic states, using low-temperature scanning tunnelling microscopy we image at the atomic scale the influence of strain-tuned lattice distortions on the correlated electronic states in the iron-based superconductor LiFeAs, a material which in its ground state is tetragonal with four-fold (C) symmetry. Our experiments uncover a new strain-stabilised modulated phase which exhibits a smectic order in LiFeAs, an electronic state which not only breaks rotational symmetry but also reduces translational symmetry. We follow the evolution of the superconducting gap from the unstrained material with C symmetry through the new smectic phase with two-fold (C) symmetry and charge-density wave order to a state where superconductivity is completely suppressed.
在许多高温超导体中，晶格结构的小正交畸变导致电子态和宏观性质的惊人的对称性破缺，这种效应通常被称为向列性。为了直接研究对称性破缺的晶格畸变对电子态的影响，我们使用低温扫描隧道显微镜在原子尺度上成像了应变调谐的晶格畸变对铁基超导体 LiFeAs 中关联电子态的影响，该材料在其基态具有四方（C）对称性。我们的实验揭示了一种新的应变稳定调制相，它在 LiFeAs 中表现出了向列有序，这种电子态不仅打破了旋转对称性，而且还降低了平移对称性。我们从具有 C 对称性的未应变材料开始，追踪超导能隙的演化，经过新的具有二倍（C）对称性和电荷密度波有序的向列相，直到超导完全被抑制的状态。
