Ultrafast spin polarization in a multiferroic manganite BiFe_0.5Mn_0.5O₃ thin film

¹ Department of Physics, Shanghai University - Shanghai 200444, China
² Institute for Superconducting and Electronic Materials, University of Wollongong - New South Wales 2500, Australia
³ Department of Materials Science and Engineering, Wuhan Institute of Technology - 693 Xiongchu Road, Wuhan 430073, China
⁴ National Institute for Materials Science - Sengen 1-2-1, Tsukuba, Ibaraki 305-0047, Japan

^(a) physics_izm@shu.edu.cn
^(b) ghma@staff.shu.edu.cn

Received: 23 September 2015
Accepted: 2 November 2015

Abstract

In this work, we present observations of ultrafast carrier dynamics and spin polarization in a multiferroic manganite BiFe_0.5Mn_0.5O₃ film excited by linearly and circularly polarized femtosecond pulses, respectively. The d-band charge transfer transition is reasonably assigned to . The transient reflectivity decay on a time scale as fast as only 0.3 ps is consistent with the picture of ultrafast electron-phonon coupling. The ultrafast switching of polarization ellipticity (< 150 fs) originates from a transient coherent spin polarization by optical orientation. The ultrafast spin polarization switching is assigned to the Raman coherence process.