Terahertz time-domain spectroscopy of electromagnons in multiferroic perovskite manganites

Abstract

Recent spectroscopic studies at terahertz frequencies for a variety of multiferroics endowed with both ferroelectric and magnetic orders have revealed the possible emergence of a new collective excitation, frequently referred to as electromagnon. It is magnetic origin, but becomes active in response to the electric field component of light. Here we give an overview on our recent advance in the terahertz time-domain spectroscopy of electromagnons or electric-dipole active magnetic resonances, focused on perovskite manganites--$R$MnO${}_3$ ($R$ denotes rare-earth ions). The respective electric and magnetic contributions to the observed magnetic resonance are firmly identified by the measurements of the light-polarization dependence using a complete set of the crystal orientations. We extract general optical features in a variety of the spin ordered phases, including the $A$-type antiferromagnetic, collinear spin ordered, and ferroelectric $bc$ and $ab$ spiral spin ordered phases, which are realized by tuning the chemical composition of $R$, temperature, and external magnetic field. In addition to the antiferromagnetic resonances of Mn ions driven by the magnetic field component of light, we clarify that the electromagnon appears only for light polarized along the a-axis even in the collinear spin ordered phase and grows in intensity with evolution of the spiral spin order, but independent of the direction of the spiral spin plane ($bc$ or $ab$) or equivalently the direction of the ferroelectric polarization $P_{\mathrm{s}}$ ($P_{\mathrm{s}}\Vert c$ or $P_{\mathrm{s}}\Vert a$). A possible origin of the observed magnetic resonances at terahertz frequencies is discussed by comparing the systematic experimental data presented here with theoretical considerations based on Heisenberg model.

arXiv comment19 pages including 15 figures and 2 tables; Invited Paper in Special Issue on Terahertz Wave Photonics in J. Opt. Soc. Am. B (Accepted for publication)

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Cited by in corpus (32)

• Chirality of Matter Shows Up via Spin Excitations
• Theory of spin-phonon coupling in multiferroic Mn perovskites
• Four-coloured Spin-wave Excitations in Multiferroic Materials
• Spin model of magnetostrictions in multiferroic Mn perovskites
• Theory of electromagnon in the multiferroic Mn perovskites: Vital role of higher harmonic components of the spiral spin order
• Theoretically predicted picosecond optical switching of spin chirality in multiferroics
• Theory of magnetoelectric resonance in two-dimensional $S=3/2$ antiferromagnet $\mathrm{B}{\mathrm{a}}_2\mathrm{CoG}{\mathrm{e}}_2{\mathrm{O}}_7$ via spin-dependent metal-ligand hybridization mechanism
• Nonreciprocal Directional Dichroism and Toroidalmagnons in Helical Magnets
• Dynamical magnetoelectric effects in multiferroic oxides
• Gigantic terahertz magnetochromism via electromagnons in hexaferrite magnet Ba${}_2$Mg${}_2$Fe${}_{12}$O${}_{22}$
• Switching of magnons by electric and magnetic fields in multiferroic borates
• Electromagnon in the Z-type hexaferrite $({\mathrm{Ba}}_x{\mathrm{Sr}}_{1-x}{)}_3\mathrm{C}{\mathrm{o}}_2\mathrm{F}{\mathrm{e}}_{24}{\mathrm{O}}_{41}$
• Electromagnon in Y-type hexaferrite BaSrCoZnFe${}_{11}$AlO${}_{22}$
• THz Magneto-electric atomic rotations in the chiral compound Ba${}_3$NbFe${}_3$Si${}_2$O${}_{14}$
• Terahertz and infrared spectroscopic evidence of phonon-paramagnon coupling in hexagonal piezomagnetic YMnO3
• A table-top, repetitive pulsed magnet for nonlinear and ultrafast spectroscopy in high magnetic fields up to 30 T
• Magnons and crystal field transitions in hexagonal REMnO3 (RE = Er, Tm, Yb, Lu) single crystals
• Microwave magnetochiral effect in Cu2OSeO3
• Shift current from electromagnon excitations in multiferroics
• Possible coupling between magnons and phonons in multiferroic CaMn7O12
• Electric polarization and nonlinear optical effects in noncentrosymmetric magnets
• Soft-mode behavior of electromagnons in multiferroic manganite
• Sinusoidal electromagnon in RMnO3: Indication of anomalous magnetoelectric coupling
• High-Frequency Electromagnon in GdMnO3
• Electromagnon in ferrimagnetic eps-Fe2O3 nanograin ceramics
• Sign change of polarization rotation under either time or space inversion in magnetoelectric YbAl3(BO3)4
• Terahertz magnetoelectric response via electromagnons in magnetic oxides
• Directly probing spin dynamics in insulating antiferromagnets using ultrashort terahertz pulses
• Numerical Simulation of Spin-Chirality Switching in Multiferroics via Intense Electromagnon Excitations
• Modifying the magnetoelectric coupling in TbMnO${}_3$ by low-level Fe${}^{3+}$ substitution
• Modeling and Physics of Multiferroic Perovskite Manganites
• Tracking a hysteretic and disorder-broadened phase transition via the electromagnon response in improper ferroelectrics