Energy-Resolved Ultrafast Spectroscopic Investigation on the Spin-Coupled Electronic States in Multiferroic Hexagonal HoMnO 3 .

A complete temperature-dependent scheme of the Mn 3+ on-site d-d transitions in multiferroic hexagonal HoMnO 3 ( h -HoMnO 3 ) thin films was unveiled by energy-resolved ultrafast spectroscopy. The results unambiguously revealed that the ultrafast responses of the e 1g and e 2g states differed significantly in the hexagonal HoMnO 3 . We demonstrated that the short-range antiferromagnetic and ferroelectric orderings are more relevant to the e 2g state, whereas the long-range antiferromagnetic ordering is intimately coupled to both the e 2g and e 1g states. Moreover, the primary thermalization times of the e 2g and e 1g states were 0.34 ± 0.08 ps and 0.38 ± 0.08 ps, respectively.