Crystal structure and phase diagrams of iron-based superconductors

Abstract

Since the discovery of high-temperature superconductivity (HTS) in iron-based compounds, a variety of systems with different spacer layers have been fabricated. Concurrently, considerable experimental and theoretical effort has been expended exploring the characteristics and source of HTS in iron-based superconductors. However, the origin of this HTS remains unresolved to date, while considerable debate exists regarding the underlying physics of the normal-state properties of iron-based compounds in particular. In this short review, we will briefly summarize the crystal structures and phase diagrams of the iron-based superconducting systems, aiming to discover potential avenues for the development of new superconductors with higher superconducting transition temperatures ( Tc), along with indications of the specifics of the HTS mechanism in these substances.

Crystal structure and superconductivity at about 30 K in ACa2Fe4As4F2 (A = Rb, Cs)

“…4 plots T c as functions of different structural parameters. One sees that T c inversely correlates with the lattice parameters a and c. This is in sharp contrast to variations of T max c in the optimally hole-doped (Ae, Ak)Fe 2 As 2 systems (T max c increases with the lattice parameters) [15][16]. Then, we consider the relevance of the spacing between Fe 2 As 2 layers.…”

“…Other complex structures consist of thicker connecting blocks between the Fe 2 X 2 layers [8][9][10][11][12][13]. These material discoveries greatly enrich the related research on IBS [14][15][16].…”

Electrical and Thermal Transport Properties of Layered Superconducting Ca10(Pt4As8)((Fe0.86Pt0.14)2As2)5 Single Crystal

“…In some cuprates, ρ ab has T 1.5 dependence, implying the Fermi-liquid behavior. Yet, the temperature dependence of the normal state ρ ab of Ca 10 (Pt 4 As 8 )((Fe 0.86 Pt 0.14 ) 2 As 2 ) 5 is neither linear, quadratic temperature dependent, nor T 1.5 dependent, as observed in cuprates or other FeAs-based compounds [10]. The normal state ρ ab from 50 K to 300 K can be well fitted by ρab=A+BT with A = 0.079 ± 0.008 mΩ cm and B = 0.031 ± 0.003 mΩ cm K −1/2 .…”

Recent progress on the high-pressure studies of FeSe single crystal

“…图 3(c)显示的是利用2. [27,28] , 而且P c 附近的 [18] 图 4 (网络版彩色)FeSe单晶的温度-压力相图. 图中T s , T m 与T c 分别 代表电子向列相、长程反铁磁序和超导转变温度 [18] Figure 4 (Color online) Temperature-pressure phase diagram of bulk FeSe, in which T s , T m , and T c represent the transition temperatures for nematic order, long-range antiferromagnetic order and the superconductivity [18] 正常态ρ(T)呈现出良好的线性温度依赖关系, 表明临 界自旋涨落可能对实现高温超导具有重要作用 [29] .…”