Reemergent phase of antiferromagnetic order in iron-based superconductor LaFe(As1-xPx)O probed by 31P-NMR

• Published in: Journal of physics. Conference series Vol. 592; no. 1
• Main Authors: Engetsu, F, Shiota, T, Lai, K T, Mukuda, H, Yashima, M, Kitaoka, Y, Miyasaka, S, Tajima, S
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 18.03.2015
• Subjects: Antiferromagnetism; Fluorine; Lattice parameters; NMR; Nuclear magnetic resonance; Physics; Superconductivity
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/592/1/012072

We report 31P-NMR studies of LaFe(As1-xPx)O compounds that revealed the reemergence of a novel antiferromagnetic(AFM) order phase (AFM2) at 0.4 ≤ x ≤ 0.7 intervening between two superconductivity phases. The AFM2 state at x=0.6 is characterized by low Néel temperature TN = 35 K and small AFM moment ~0.18μB, which is in strong contrast to the AFM order phase(AFMl) at x=0 with larger AFM moment and higher TN. This finding provides a reasonable explanation for the previous experimental fact that the AFM spin fluctuations and Tc are unexpectedly enhanced in x=0.6 of LaFe(As1-xPx)(O0.95F0.05) even though its lattice parameters deviate from the optimum values, that is, the AFM spin fluctuations at low energies are enhanced as a result of the depression of AFM2 by electron doping through fluorine substitution.