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Direct visualization of phase separation between superconducting and nematic domains in Co-doped CaFe2As2 close to a first-order phase transition

TitleDirect visualization of phase separation between superconducting and nematic domains in Co-doped CaFe2As2 close to a first-order phase transition
Publication TypeJournal Article
Year of Publication2018
AuthorsFente, A, Correa-Orellana, A, Bohmer, AE, Kreyssig, A, Ran, S, Bud'ko, SL, Canfield, PC, Mompean, FJ, Garcia-Hernandez, M, Munuera, C, Guillamon, I, Suderow, H
JournalPhysical Review B
Volume97
Pagination014505
Date Published01
Type of ArticleArticle
ISBN Number2469-9950
Accession NumberWOS:000419613800005
Keywordsca(fe1-xcox)(2)as-2, criticality, lattice, line, physics, quantum critical-points, states, temperature
Abstract

We show that biaxial strain induces alternating tetragonal superconducting and orthorhombic nematic domains in Co-substituted CaFe2As2. We use atomic force, magnetic force, and scanning tunneling microscopy to identify the domains and characterize their properties, finding in particular that tetragonal superconducting domains are very elongated, more than several tens of micrometers long and about 30 nm wide; have the same T-c as unstrained samples; and hold vortices in a magnetic field. Thus, biaxial strain produces a phase-separated state, where each phase is equivalent to what is found on either side of the first-order phase transition between antiferromagnetic orthorhombic and superconducting tetragonal phases found in unstrained samples when changing Co concentration. Having such alternating superconducting domains separated by normal conducting domains with sizes of the order of the coherence length opens opportunities to build Josephson junction networks or vortex pinning arrays and suggests that first-order quantum phase transitions lead to nanometric-size phase separation under the influence of strain.

DOI10.1103/PhysRevB.97.014505
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