Publication Date

10-5-2018

Department

Ames Laboratory; Physics and Astronomy

Campus Units

Physics and Astronomy, Ames Laboratory

OSTI ID+

1478232

Report Number

IS-J 9778

DOI

10.1103/PhysRevMaterials.2.104802

Journal Title

Physical Review Materials

Volume Number

2

Issue Number

10

First Page

104802

Abstract

A lately discovered 1144 phase has generated significant interest for its high superconducting temperatures, disorder-free doping, and various chemical substitutions. However, it has only been found in iron arsenides ( A B Fe 4 As 4 ), and cations are limited to +1 or +2 valence states (e.g., alkali metals, alkaline earth elements, and Eu). Whether more 1144 phases could be stabilized and whether intriguing properties exist are questions of general interest. In this work, we investigate 1144 iron and cobalt arsenides with tri-valence cations (La, Y, In, Tl, Sm, Gd). We study phase stability among other competing phases: 122 solution phase and phase decomposition. With La as the cation, we predict room-temperature stable 1144 structures: La A Fe 4 As 4 ( A = K , Rb, and Cs). Other La-contained 1144 structures tend to form solution phase. The solubility of La is estimated and compared with the experiment. By contrast, we do not find stable 1144 structures with Y as the cation. For In and Tl as cations, two 122-phase compounds are remarkably stable: InCo 2 As 2 and TlCo 2 As 2 , which adds to our knowledge about the In(Tl)-Co-As phase diagram. Stable 1144 phases are found in InKCo 4 As 4 and InRbCo 4 As 4 . With Sm and Gd as cations, 1144- or 122-phase iron arsenides are generally unstable. Among structures investigated, we recognize two critical factors for 1144-phase stability: size effect and charge balance, which yields a merging picture with the rule found in previous 1144 systems. Moreover, La A Fe 4 As 4 ( A = K , Rb, and Cs), InCo 2 As 2 , and TlCo 2 As 2 are exhibiting semimetal features and a two-dimensional Fermi surface, similar to iron superconductors.

DOE Contract Number(s)

AC02-07CH11358

Language

en

Department of Energy Subject Categories

36 MATERIALS SCIENCE

Publisher

Iowa State University Digital Repository, Ames IA (United States)

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