Authors: Tiege Zhou
Electric field effects in iron- and copper-based superconductors were studied by using the first-principles calculations based on the density functional theory (DFT). The research objects include iron-based superconductors (KFe2Se2, LaFeAsO, NdFeAsO, and BaFe2As2) and copper-based superconductors (YBa2Cu3O7, HgBa2Ca2Cu3O8, Tl2Ba2CaCu2O8, and Bi2Sr2Ca2Cu3O10). To describe the strong correlation effect of 3d-electrons or 4f-electrons, the GGA+U method was used. Some results were further verified by the HSE method. The densities of states (DOS) were given. The change of the charge densities under electric fields is presented to demonstrate the electric field effect. It is found that the electron clouds of Fe ions in iron-based superconductors, Nd ions in Nd2Fe2As2O2, and Cu ions in copper-based superconductors change obviously. The pattern of the change is more like a rigid-body rotation than an elastic deformation. The author proposed that the rotation of the electron clouds of transition metal ions may be a new medium of superconducting electron pairing. The author’s views about some issues and suggestions on follow-up studies are also presented.
Comments: 20 Pages.
[v1] 2018-04-23 18:27:45
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