Indication of subdominant d-wave interaction in superconducting CaKFe4 As4

Jost, D.; Scholz, J. -R.; Zweck, U.; Meier, W. R.; Böhmer, A.  E.; Canfield, P. C.; Lazarević, N.; Hackl, R.

doi:10.1103/PhysRevB.98.020504

Title: Indication of subdominant d-wave interaction in superconducting CaKFe₄ As₄

Journal Article · 01 July 2018 · Physical Review B

DOI: https://doi.org/10.1103/PhysRevB.98.020504 · OSTI ID:1464473

Jost, D. ^[1]; Scholz, J. -R. ^[1]; Zweck, U. ^[1]; Meier, W. R. ^[2]; Böhmer, A. E. ^[3]; Canfield, P. C. ^[4]; Lazarević, N. ^[5]; Hackl, R. ^[6]

Bayerische Akademie der Wissenschaften, Garching (Germany). Walther Meissner Inst.; Technical University of Munich, Garching (Germany). Fakultät für Physik E23
Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy
Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy; Ames Lab., Ames, IA (United States). Division of Materials Science and Engineering
Ames Lab., Ames, IA (United States). Division of Materials Science and Engineering; Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy
Univ. of Belgrade, Belgrade (Serbia). Center for Solid State Physics and New Materials, Inst. of Physics Belgrade
Bavarian Academy of Sciences and Humanities, Garching (Germany). Walther Meissner Inst.

We report inelastic light scattering results on the stoichiometric and fully ordered superconductor CaKFe₄ As₄ as a function of temperature and light polarization. In the energy range between 10 and 315 cm^-1 (1.24 and 39.1 meV) we observe the particle-hole continuum above and below the superconducting transition temperature T_c and seven of the eight Raman active phonons. The main focus is placed on the analysis of the electronic excitations. Below T_c all three symmetries projected with in-plane polarizations display a redistribution of spectral weight characteristic for superconductivity. The energies of the pair-breaking peaks in A_1g and B_2g symmetry are in approximate agreement with the results from photoemission studies. In B_1g symmetry the difference between the normal and superconducting state is most pronounced, and the feature is shifted downwards with respect to those in A_1g and B_2g symmetry. The maximum peaking at 134 cm^-1 (16.6 meV) has a substructure on the high-energy side. We interpret the peak at 134 cm^-1 in terms of a collective Bardasis-Schrieffer (BS) mode and the substructure as a remainder of the pair-breaking feature on the electron bands. Finally, there is a very weak peak at 50 cm^-1 (6.2 meV) which is tentatively assigned to another BS mode.

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Research Organization:: Ames Laboratory (AMES), Ames, IA (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; German Academic Exchange Service (DAAD); Serbian Ministry of Education, Science and Technological Development; Gordon and Betty Moore Foundation (GBMF); USDOE

Grant/Contract Number:: 56267076; 57142964; AC02-07CH11358; GBMF4411

OSTI ID:: 1464473

Alternate ID(s):: OSTI ID: 1460127

Report Number(s):: IS-J-9711; PRBMDO; TRN: US1902388

Journal Information:: Physical Review B, Vol. 98, Issue 2; ISSN 2469-9950

Publisher:: American Physical Society (APS)Copyright Statement

Country of Publication:: United States

Language:: English

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