Abstract-Terahertz spectroscopy of low-energy excitations in E u 0.42 S r 0.58 Mn O 3

L. S. Kadyrov, E. S. Zhukova, V. I. Torgashev, T. Zhang, Z. V. Gagkaeva, M. Dressel, and B. P. Gorshunov

https://journals.aps.org/prb/abstract/10.1103/PhysRevB.96.245120

The origin of low-energy excitations in the polycrystalline $E{u}_{0.42}S{r}_{0.58}\mathrm{Mn}{O}_3$ manganite is explored by terahertz and infrared spectroscopies. The transition from the charge and/or orbital to antiferromagnetic order ($T_N=130-140K$) is seen as smooth (spread over a temperature range from 50 to 100 K) decrease of free-carrier conductivity with the activation energy change from 86 meV (high temperatures) to 0.52 meV (low temperatures). A broad relaxation is observed at around $10c{m}^{-1}$ which we associate with the dynamics of free charge carriers in the presence of random localizing potential. We discover an absorption resonance at $\approx 50c{m}^{-1}$ below $T_N$ that is assigned to the formation of hybridized “acoustic phonon-magnon” quasiparticles.

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