^{75}As NMR study of the growth of paramagnetic-metal domains due to electron doping near the superconducting phase in LaFeAsO_{1-x}F_{x}

Abstract

We studied the electric and magnetic behavior near the phase boundary between antiferromagnetic (AF) and superconducting (SC) phases for a prototype of high-T_c pnictides LaFeAsO_{1-x}F_{x} by using nuclear magnetic resonance, and found that paramagnetic-metal (PM) domains segregate from AF domains. PM domains grow in size with increasing electron doping level and are accompanied by the onset of superconductivity, and thus application of pressure or increasing the doping level causes superconductivity. The existence of PM domains cannot be explained by the existing paradigm that focuses only on the relationship between superconductivity and antiferromagnetism. Based on orbital fluctuation theory, the existence of PM domains is evidence of the ferroquadrupole state.

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Cited by in corpus (4)

• Quantum critical behavior in heavily doped LaFeAsO${}_{1-x}$H${}_x$ pnictide superconductors analyzed using nuclear magnetic resonance
• Experimental evidence of $T_c$ enhancement without the influence of spin fluctuations: NMR study on LaFeAsO_{1-x}H_x under a pressure of 3.0 GPa
• A unified phase diagram of F-doped LaFeAsO by means of NMR and NQR parameters
• Spin density wave and superconductivity in CaFe_{1-x}Co_{x}AsF studied by nuclear magnetic resonance