paper

Spin dynamics near a putative antiferromagnetic quantum critical point in Cu substituted BaFe $_{2}$ As $_{2}$ and its relation to high-temperature superconductivity

arXiv:1510.04167 · doi:10.1103/PhysRevB.92.214404

Abstract

We present the results of elastic and inelastic neutron scattering measurements on non-superconducting Ba(Fe $_{0.957}$ Cu $_{0.043}$ ) $_{2}$ As $_{2}$ , a composition close to a quantum critical point between AFM ordered and paramagnetic phases. By comparing these results with the spin fluctuations in the low Cu composition as well as the parent compound BaFe $_{2}$ As $_{2}$ and superconducting Ba(Fe $_{1 - x}$ Ni $_{x}$ ) $_{2}$ As $_{2}$ compounds, we demonstrate that paramagnon-like spin fluctuations are evident in the antiferromagnetically ordered state of Ba(Fe $_{0.957}$ Cu $_{0.043}$ ) $_{2}$ As $_{2}$ , which is distinct from the AFM-like spin fluctuations in the superconducting compounds. Our observations suggest that Cu substitution decouples the interaction between quasiparticles and the spin fluctuations. We also show that the spin-spin correlation length, $I^¾ (T)$ , increases rapidly as the temperature is lowered and find $I ¨ / T$ scaling behavior, the hallmark of quantum criticality, at an antiferromagnetic quantum critical point.

10 pages, 7 figures

Spin dynamics near a putative antiferromagnetic quantum critical point in Cu substituted BaFe2​As2​ and its relation to high-temperature superconductivity

Abstract

Spin dynamics near a putative antiferromagnetic quantum critical point in Cu substituted BaFe $_{2}$ As $_{2}$ and its relation to high-temperature superconductivity