Competing effects of Mn and Y doping on the low-energy excitations and phase diagram of La$_{1-y}$Y$_{y}$Fe$_{1-x}$Mn$_x$AsO$_{0.89}$F$_{0.11}$ iron-based superconductors

M. Moroni; S. Sanna; G. Lamura; T. Shiroka; R. De Renzi; R. Kappenberger; S. Wurmehl; A. U. B. Wolter; M. A. Afrassa; B. Büchner; P. Carretta

doi:10.1103/PhysRevB.94.054508

paper

Competing effects of Mn and Y doping on the low-energy excitations and phase diagram of La $_{1 - y}$ Y $_{y}$ Fe $_{1 - x}$ Mn $_{x}$ AsO $_{0.89}$ F $_{0.11}$ iron-based superconductors

arXiv:1605.09334 · doi:10.1103/PhysRevB.94.054508

Abstract

Muon Spin Rotation ( $μ$ SR) and $^{19}$ F Nuclear Magnetic Resonance (NMR) measurements were performed to investigate the effect of Mn for Fe substitutions in La $_{1 - y}$ Y $_{y}$ Fe $_{1 - x}$ Mn $_{x}$ AsO $_{0.89}$ F $_{0.11}$ 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. 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 $1/ T_{1}$ 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 LaFeAsO $_{0.89}$ F $_{0.11}$ to a quantum critical point.

arXiv comment8 pages, 9 figures

Competing effects of Mn and Y doping on the low-energy excitations and phase diagram of La $_{1 - y}$ Y $_{y}$ Fe $_{1 - x}$ Mn $_{x}$ AsO $_{0.89}$ F $_{0.11}$ iron-based superconductors

Abstract

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Competing effects of Mn and Y doping on the low-energy excitations and phase diagram of La1−y​Yy​Fe1−x​Mnx​AsO0.89​F0.11​ iron-based superconductors

Abstract

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Cited by in corpus (6)

Competing effects of Mn and Y doping on the low-energy excitations and phase diagram of La $_{1 - y}$ Y $_{y}$ Fe $_{1 - x}$ Mn $_{x}$ AsO $_{0.89}$ F $_{0.11}$ iron-based superconductors