Ultrafast inverse Faraday effect in a paramagnetic terbium gallium garnet crystal

Abstract

Conventional wisdom dictates that magneto-optical and optomagnetic phenomena are reciprocal and of equal strength. We test this assumption in a pump-probe experimental study of the ultrafast inverse Faraday effect in a terbium gallium garnet crystal. The thorough quantitative analysis of the observed polarization response unambiguously demonstrates a remarkable discrepancy of several orders of magnitude between the strengths of the direct and the inverse effects. This finding further questions the validity of standard magnetic models relying on the use of the static Verdet constant on subpicosecond time scales.

Terahertz Cherenkov radiation from ultrafast magnetization in terbium gallium garnet

“…Recently, the transient magnetization induced in a terbium gallium garnet (TGG) crystal by a circularly polarized femtosecond laser pulse was measured by means of the optical-pump-optical-probe technique. 12 Surprisingly, the measured Faraday rotation of the probe beam polarization was four orders of magnitude larger than predicted by the standard theory of IFE with the quasistatic Verdet constant. 8 Moreover, it was argued in Ref.…”

“…9 Nowadays, the mechanism of the effect on the subpicosecond time scale, i.e., ultrafast IFE, is under intense debate. [10][11][12] The main experimental approaches to exploring ultrafast optomagnetic phenomena include the pump-probe technique 13 and terahertz emission spectroscopy, i.e., measuring terahertz radiation from optically excited materials. 14 In typical optomagnetic experiments, the oscillations of magnetization lasting a long time after termination of the subpicosecond pump laser pulse are detected.…”

Improving Faraday rotation performance with block copolymer and FePt nanoparticle magneto-optical composite

“…Acceptable MO performance in a composite generally requires the dispersion of a large volume fraction of MO nanoparticles, which often leads to light losses through scattering, thereby decreasing transparency and useful FR response [22,23]. Today's benchmark MO materials include ferromagnetic terbium gallium garnet (TGG, Tb 3 Ga 5 O 12 ) [24][25][26][27][28] and bismuth (Bi) doped yttrium iron garnet (Bi:YIG, Y 2 Fe 5 O 12 ) [29][30][31][32][33], targeting visible and near infrared (NIR) regimes, respectively. However, this family of materials containing rare-earth elements is usually produced as single crystals in order to achieve millimeter-scale path lengths for excellent MO performance [27,29,31].…”

“…Today's benchmark MO materials include ferromagnetic terbium gallium garnet (TGG, Tb 3 Ga 5 O 12 ) [24][25][26][27][28] and bismuth (Bi) doped yttrium iron garnet (Bi:YIG, Y 2 Fe 5 O 12 ) [29][30][31][32][33], targeting visible and near infrared (NIR) regimes, respectively. However, this family of materials containing rare-earth elements is usually produced as single crystals in order to achieve millimeter-scale path lengths for excellent MO performance [27,29,31]. The high processing costs associated with high-quality crystal growth and limited achievable film thickness have restricted their broader utilization [26,32,33].…”

Light-induced spin polarizations in quantum rings

“…The reciprocity between FE and IFE is not universally observed [11], and was found by theory to break down in the presence of absorption [12]. Taguchi et al calculated the effect of terahertz electromagnetic radiation on disordered metals with spin-orbit interaction (SOI) [13].…”