Terahertz Faraday rotation induced by an anomalous Hall effect in the itinerant ferromagnet SrRuO₃

¹ Multiferroics Project, ERATO, Japan Science and Technology Agency (JST) - Tokyo 113-8656, Japan
² Department of Physics, University of Tokyo - Tokyo 113-0033, Japan
³ Cross-correlated Research Group(CMRG) and Correlated Electron Research Group(CERG), Advanced Science Institute, RIKEN - Wako 351-0198, Japan
⁴ WPI Advanced Institute for Materials Research and Institute for Materials Research, Tohoku University Sendai 980-8577, Japan
⁵ Department of Applied Physics, University of Tokyo - Tokyo 113-8656, Japan

^a shimano@phys.s.u-tokyo.ac.jp

Received: 1 April 2011
Accepted: 11 May 2011

Abstract

We report on the observation of Faraday rotation in the terahertz frequency range in a thin film of itinerant ferromagnet, SrRuO₃. As optical counterpart of the anomalous Hall effect (AHE), the complex optical Hall conductivity spectrum σ_xy(ω) was extracted from the Faraday rotation and ellipticity spectrum. The temperature and frequency (ω) dependences of σ_xy(ω) in the terahertz regime are consistently connected with the dc AHE. A clear resonance structure is identified in the σ_xy(ω) spectrum right below the Fermi level as the plausible origin of the large dc AHE.