# {\omega}/T scaling and magnetic quantum criticality in BaFe2(As0.7P0.3)2

## TL;DR

This study reveals ω/T scaling and magnetic quantum criticality in optimally doped BaFe2(As0.7P0.3)2, linking strange-metal behavior with a nearby quantum critical point and the weakly first-order transition out of antiferromagnetic order.

## Contribution

It demonstrates ω/T scaling in spin susceptibility and resistivity extending up to high temperatures, indicating magnetic quantum criticality in a clean iron pnictide superconductor.

## Key findings

- Resistivity shows linear temperature dependence up to ~500 K.
- Spin susceptibility exhibits ω/T scaling over a wide energy range.
- Results suggest a magnetic quantum critical point near optimal doping.

## Abstract

We used transport and inelastic neutron scattering to study the optimally phosphorus-doped BaFe$_2$(As$_{0.7}$P$_{0.3}$)$_2$ superconductor ($T_c = 30$ K). In the normal state, we find that the previously reported linear temperature dependence of the resistivity below room temperature extends to $\sim$ 500 K. Our analysis of the temperature and energy ($E=\hbar\omega$) dependence of spin dynamical susceptibility at the antiferromagnetic (AF) ordering wave vector $\chi^{\prime\prime}({\bf Q}_{\rm AF},\omega)$ reveal an $\omega / T$ scaling within $1.1<E/k_BT<110$. These results suggest that the linear temperature dependence of the resistivity is due to the presence of a magnetic quantum critical point in the cleanest iron pnictides near optimal superconductivity. Moreover, the results reconcile the strange-metal temperature dependences with the weakly first-order nature of the quantum transition out of the AF and nematic orders.