Evolution of the low energy spin dynamics in electron-doped   high-transition temperature superconductor Pr0.88LaCe0.12CuO4-d
  We use inelastic neutron scattering to explore the evolution of the low energy spin dynamics in the electron-doped cuprate Pr0.88LaCe0.12CuO4-d (PLCCO) as the system is tuned from its nonsuperconducting, as-grown antiferromagnetic (AF) state into an optimally-doped superconductor (Tc~24 K) without static AF order. The low temperature, low energy response of the spin excitations in under-doped samples is coupled to the presence of the AF phase, whereas the low-energy magnetic response for samples near optimal Tc exhibits spin fluctuations surprisingly insensitive to the sample temperature. This evolution of the low energy excitations is consistent with the influence of a quantum critical point in the phase diagram of PLCCO associated with the suppression of the static AF order. We carried out scaling analysis of the data and discuss the influence of quantum critical dynamics in the observed excitation spectrum. 
Stephen D. Wilson, Shiliang Li, Pengcheng Dai, Wei Bao, Jae-Ho Chung,   H. J. Kang, Seung-Hun Lee, Seiki Komiya, Yoichi Ando...