Quantum Phase transition under pressure in a heavily hydrogen-doped iron-based superconductor LaFeAsO

Abstract

Hydrogen (H)-doped LaFeAsO is a prototypical iron-based superconductor. However, its phase diagram extends beyond the standard framework, where a superconducting (SC) phase follows an antiferromagnetic (AF) phase upon carrier doping; instead, the SC phase is sandwiched between two AF phases appearing in lightly and heavily H-doped regimes. We performed nuclear magnetic resonance (NMR) measurements under pressure, focusing on the second AF phase in the heavily H-doped regime. The second AF phase is strongly suppressed when a pressure of 3.0 GPa is applied, and apparently shifts to a highly H-doped regime, thereby a "bare" quantum critical point (QCP) emerges. A quantum critical regime emerges in a paramagnetic state near the QCP, however, the influence of the AF critical fluctuations to the SC phase is limited in the narrow doping regime near the QCP. The optimal SC condition ($T_c\sim$ 48 K) is unaffected by AF fluctuations.

References in corpus (10)

• Fermi-liquid instabilities at magnetic quantum phase transitions
• Coexistence of the spin-density-wave and superconductivity in the (Ba,K)Fe2As2
• Bipartite magnetic parent phases in the iron-oxypnictide superconductor
• Pressure-induced antiferromagnetic transition and phase diagram in FeSe
• Superconductivity at 52 K in hydrogen-substituted LaFeAsO1-xHx under high pressure
• Evolution of the Phase Diagram of LaFeP${}_{1-x}$As${}_x$O${}_{1-y}$F${}_y$ ($y$ = 0 -- 0.1)
• Systematic ^{75}As NMR study of the dependence of low-lying excitations on F doping in the iron oxypnictide LaFeAs(O_{1-x}F_{x})
• Quantum critical behavior in heavily doped LaFeAsO${}_{1-x}$H${}_x$ pnictide superconductors analyzed using nuclear magnetic resonance
• Heavy Electron doping-induced antiferromagnetic phase as the parent for iron-oxypnictide superconductor LaFeAsO1-xHx
• 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

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