Effect of laser pulse propagation on ultrafast magnetization dynamics in a birefringent medium

Abstract

Light propagation effects can strongly influence the excitation and the detection of laser-induced magnetization dynamics. We investigated experimentally and analytically the effects of crystallographic linear birefringence on the excitation and detection of ultrafast magnetization dynamics in the rare-earth orthoferrites (SmPr)FeO and (SmTb)FeO, which possess weak and strong linear birefringence, respectively. Our finding is that the effect of linear birefringence on the result of a magneto-optical pump-probe experiment strongly depends on the mechanism of excitation. When magnetization dynamics, probed by means of the Faraday effect, is excited via a rapid, heat-induced phase transition, the measured rotation of the probe pulse polarization is strongly suppressed due to the birefringence. This contrasts with the situation for magnetization dynamics induced by the ultrafast inverse Faraday effect, where the corresponding probe polarization rotation values were larger in the orthoferrite with strong linear birefringence. We show that this striking difference results from an interplay between the polarization transformations experienced by pump and probe pulses in the birefringent medium.

Heat diffusion in magnetic superlattices on glass substrates

“…The equilibrium magnetization magnitude and direction is determined by a balance of several energies that depend on these factors and implicitly on temperature. For instance, temperature increases induced by laser beams can modify the equilibrium conditions and start a magnetization precession, switch it between different easy axis minima [6,7], or modify the magnetization hysteresis loops in applied fields [8]. Magnetic structures induced by laser beams [9,10,11,12,13], all-optical switching (AOS) in thin ferrimagnetic rare-earth and ferromagnetic superlattices [14,15], hybrid structures [16] and granular media [17,18] have been observed.…”

Quantum theory of femtosecond optomagnetic effects for rare-earth ions in DyFeO3

“…Specifically for (A2), taking into account only the 4 f N−1 5d configuration, we get H (5) me = − α E α D effα , m , m = ±4, ±5, ±6. In the general case, operators of the effective dipole moment D effα are of the form (13); in this case, V odd accounts the seventh-order terms and 4 f N−1 5g configurations.…”

“…The problem of conservation and transfer of angular momentum has become the central issue of this research field [2][3][4][5][6]. It is remarkable that although most of the theories in ultrafast magnetism take into account only the magnetism of spins, the most intriguing experimental results have been obtained on compounds containing rare-earth ions, for which the spinorbit interaction is so strong that spin and orbital moments are not mutually independent, and orbitals contribute substantially to the net magnetization [7][8][9][10][11][12][13][14][15][16][17][18].…”

Ultrafast magnetization dynamics in the vicinity of spin reorientation transition in TbCo2/FeCo heterostructures

“…The proximity to the magnetic phase transition of order-order type increases the spin system sensitivity to external impacts and creates favorable conditions for observation of optically induced phenomena. Usually either materials with natural SRT (induced by temperature changing) [5][6][7] or heterostructures based on them [8,9] are studied.…”