Impact of concomitant Y and Mn substitution on superconductivity in La1−yYyFe1−xMnx

Competing effects of Mn and Y doping on the low-energy excitations and phase diagram ofLa1−yYyFe1−xMnxMoroni1, Sanna2, Lamura3 et al. 2016Phys. Rev. B9370View full textAdd to dashboardCite

“…Furthermore the related activation energies E a and correlation time τ 0 are almost insensitive to the Mn content indicating that the low-frequency dynamics is nearly unaltered when approaching the disruption of superconductivity. Bumps in the 1/T 1 vs T behaviour have also been detected in other optimally electron-doped iron-based superconductors [34][35][36][37] in the same T range where the peak in 19 F NMR 1/T 1 arises in Fig. 5.…”

“…The origin of the low-energy fluctuations giving rise to the peak in 19 F NMR 1/T 1 is not yet clear. They seem to be intrinsic to the system since they are detected also for the LaY20 compound without manganese.…”

“…A magnetic phase arises once superconductivity is suppressed both for y=0 and for y = 20%. Low-energy spin fluctuations give rise to a peak in 19 F NMR 1/T1 with an onset well above the superconducting transition temperature and whose magnitude increases with x. Also the static magnetic correlations probed by 19 F NMR linewidth measurements show a marked increase with Mn content.…”

“…Low-energy spin fluctuations give rise to a peak in 19 F NMR 1/T1 with an onset well above the superconducting transition temperature and whose magnitude increases with x. Also the static magnetic correlations probed by 19 F NMR linewidth measurements show a marked increase with Mn content. The disruption of superconductivity and the onset of the magnetic ground-state are discussed in the light of the proximity of LaFeAsO0.89F0.11 to a quantum critical point.…”

“…Muon Spin Rotation (µSR ) and 19 F Nuclear Magnetic Resonance (NMR) measurements were performed to investigate the effect of Mn for Fe substitutions in La1−yYyFe1−xMnxAsO0.89F0.11 superconductors. While for y = 0 a very low critical concentration of Mn (x = 0.2%) is needed to quench superconductivity, as y increases the negative chemical pressure introduced by Y for La substitution stabilizes superconductivity and for y = 20% it is suppressed at Mn contents an order of magnitude larger.…”