Magnetic and nematic quantum bicritical point in Ba(Fe0.97Cr0.03)2(As1-xPx)2

The disappearance of long-range order in metallic system may result in a quantum critical point (QCP) that is believed to be crucial in understanding unconventional superconductivity in many materials. Both the antiferromagnetic and nematic quantum critical points have been suggested to present in iron-based superconductors, but they are always preempted by superconductivity. Here we show that just 3\% of Cr doping can fully suppress superconductivity and reveal a quantum critical point in the BaFe2(As1-xPx)2 system, which corresponds to the disappearance of both the antiferromagnetic and nematic orders. We found that the antiferromagnetic transition temperature and the magnetic moment decrease linearly upon the phosphorus doping till the QCP, with a V-shaped region of T-linear resistance, which suggests the position of the QCP significantly shifts from that in the superconducting system.