Coherent Control of Spin Precession Motion with Impulsive Magnetic Fields of Half-Cycle Terahertz Radiation

Abstract

Coherent control of the precession motion of magnetizations in a single crystal YFeO3 with double half-cycle pulse terahertz waves was demonstrated. Quasiferromagnetic (0.299 THz) and quasiantiferromagnetic (0.527 THz) precession modes were selectively excited by choosing an appropriate interval of two pulses and were observed as free induction decay (FID) signals from the spin system. By observing the circularly polarized FID signals due to ferromagnetic resonance, we also succeeded in confirming directly the energy storage in the spin system and recovery from that to the electromagnetic radiation.

Terahertz emission spectroscopy of laser-induced spin dynamics inTmFeO3andErFeO3orthoferrites

“…By analyzing absorption peaks in the normalized Fourier spectra of the pulses transmitted through the sample, one can obtain information about the spectrum of THz excitations in the sample. The details of the time-domain THz spectroscopy setup can be found elsewhere [22][23][24][25][26][27]. We analyze the THz transmission through the sample in terms of the normalized loss function σ (ω), defined as…”

“…It has been demonstrated that broadband pulses of THz radiation can serve as a probe of spin resonances in YFeO 3 [22][23][24], ErFeO 3 [25], NdFeO 3 [26], and Tb 3 Ga 5 O 12 [27]. A promising approach to control magnetic order with the help of intense-enough THz pulses has been suggested for NiO [28].…”

Single-pulse terahertz coherent control of spin resonance in the canted antiferromagnet YFeO3, mediated by dielectric anisotropy

“…25 Similarly, an all-THz experiment involving a pair of much weaker THz pulses was used for coherent control of the spin precession in yttrium orthoferrite (YFeO 3 ). 27 In this paper, we show the coherent control of the quasi-FM spin resonance at the frequency of 0.3 THz in the canted AFM crystal YFeO 3 using only a single incident THz pulse. The amplitude and the phase of the THz spin waves can be controlled coherently by choosing the polarization of the incident THz pulse with respect to the symmetry axes of the anisotropic crystal.…”

“…16,17 Recently, the ultrafast THz spectroscopy also proved to be an effective experimental method of detection and manipulation of magnetization in materials utilizing the magnetic field component of the THz transient through magnetic dipole transitions. [18][19][20][21][22] In this fashion, the ultrafast magnetization dynamics in ferromagnetic (FM) 23 and antiferromagnetic (AFM) materials [24][25][26][27] have been investigated.…”

“…As a result of the impulsive Zeeman torque, the tilted macroscopic magnetization vector M starts precessing around its unperturbed orientation at the Larmor frequency, leading to circularly polarized electromagnetic emission E THz ∝ ∂ 2 M/∂t 2 (where t is time) from the rotating magnetic dipole, in the direction of an unperturbed M vector, at the Larmor frequency. [24][25][26][27] The excitation of spin waves by an impulsive, (sub-) picosecond, magnetic field transient can be considered quasiinstantaneous. However, the natural decay of the spin waves, which can be assigned to magnon-magnon or magnon-phonon interactions, 25,28 usually takes place on the timescale of tens to hundreds of picoseconds.…”