Ultrafast optical polarimetry in magnetic phases of Kondo semi metal CeSb

TL;DR

This study uses ultrafast magneto-optical spectroscopy to explore magnetic phase-dependent dynamics in CeSb, revealing new coherent excitations and phase-specific electronic relaxation behaviors.

Contribution

It uncovers a previously undetected Ce^{3+} crystal-field excitation and compares magnetic phase dynamics, advancing understanding of CeSb's ultrafast magnetic and electronic properties.

Findings

Identification of a new Ce^{3+} crystal-field excitation.

Distinct oscillation frequencies in AF and F phases.

Faster electronic relaxation in ferromagnetic phases.

Abstract

We investigated photoinduced ultrafast transient dynamics in different magnetic phases in CeSb by means of the time resolved magneto-optical spectroscopy. We observe a distinctive coherent oscillations in the ground-state antiferromagnetic (AF) phase and the high-magnetic field ferromagnetic (F) phase. While the AF-phase oscillations frequencies match the recent Raman scattering findings the F-phase oscillation frequency does not correspond to the previously observed magnetic excitation. The large spectroscopic factor, g=3.94, and optical polarization properties suggest that it corresponds to a previously undetected Ce^{3+} coherent crystal-field state excitation. The AF-phase oscillations show no magnetic field dependence so their lattice origin cannot be entirely excluded. The non-oscillatory part of the transients is qualitatively similar in all investigated magnetic phases with a faster sub-picosecond dynamics in the ferromagnetic and ferro-para-magnetic phases and is attributed to differences in the electronic structure, which affect the photo-excited quasiparticle energy relaxation kinetics.