Coexistence of antiferromagnetic and ferromagnetic spin correlations inSrCo2As2revealed byCo59and<

Competing Magnetic Fluctuations in Iron Pnictide Superconductors: Role of Ferromagnetic Spin Correlations Revealed by NMR

“…Since stripe-type AFM fluctuations are a key ingredient to SC in the iron pnictides, this result suggested that FM fluctuations might compete with the stripe-type AFM fluctuations, suppressing SC in SrCo 2 As 2 . FM correlations were also observed in isostructural BaCo 2 As 2 [2,4]. Similarly, CaCo 1.86 As 2 has an A-type AFM ground state with inplane FM order [5].…”

“…In the standard picture, carrier doping or pressure application results in suppression of the AFM order and the emergence of a SC state, with T c ranging from a few K to 56 K [1]. However, as of yet, there is no accepted theory for T c in these materials with which to explain the large variability in maximum T c between different iron arsenide families and the different shapes of the SC dome with electron and hole doping.Recent nuclear magnetic resonance (NMR) measurements on non-SC, paramagnetic (PM) SrCo 2 As 2 , the x = 1 member of the electron-doped Sr(Fe 1−x Co x ) 2 As 2 family, revealed strong ferromagnetic (FM) spin fluctuations in the Co layer coexisting with stripe-type AFM fluctuations [2,3]. Since stripe-type AFM fluctuations are a key ingredient to SC in the iron pnictides, this result suggested that FM fluctuations might compete with the stripe-type AFM fluctuations, suppressing SC in SrCo 2 As 2 .…”

“…Recent nuclear magnetic resonance (NMR) measurements on non-SC, paramagnetic (PM) SrCo 2 As 2 , the x = 1 member of the electron-doped Sr(Fe 1−x Co x ) 2 As 2 family, revealed strong ferromagnetic (FM) spin fluctuations in the Co layer coexisting with stripe-type AFM fluctuations [2,3]. Since stripe-type AFM fluctuations are a key ingredient to SC in the iron pnictides, this result suggested that FM fluctuations might compete with the stripe-type AFM fluctuations, suppressing SC in SrCo 2 As 2 .…”

“…We also used our existing data on BaCo 2 As 2 , reported elsewhere [2,11] and other data from the literature. The 75 As NMR shift and spin-lattice relaxation rates 1/T 1 were measured under magnetic fields parallel to the c axis (H c) and to the ab plane (H ab).…”

Suppression of magnetic order in CaCo1.86As2 with Fe substitution: Magnetization, neutron diffraction, and x-ray diffraction studies of Ca(CoJayasekara1, Pandey2, Kreyßig3 et al. 2017Phys. Rev. BSelf Cite212410View full textAdd to dashboardCite

“…33 Additionally, inelastic neutron scattering data for SrCo 2 As 2 show the presence of AFM spin fluctuations peaked at wavevectors corresponding to the stripe-type AFM order present in AFe 2 As 2 (A = Ca, Sr, Ba), 34 and nuclear magnetic resonance experiments find that AFM and FM spin correlations coexist in the compound. 35 Thus, it is prudent to study how the lattice and magnetism change in CaCo 1.86 As 2 as either Fe is substituted for Co, or Sr/Ba is substituted for Ca.…”