Chiral Spin-Wave Velocities Induced by All-Garnet Interfacial Dzyaloshinskii-Moriya Interaction in Ultrathin Yttrium Iron Garnet Films

Abstract

Spin waves can probe the Dzyaloshinskii-Moriya interaction (DMI) which gives rise to topological spin textures, such as skyrmions. However, the DMI has not yet been reported in yttrium iron garnet (YIG) with arguably the lowest damping for spin waves. In this work, we experimentally evidence the interfacial DMI in a 7 nm-thick YIG film by measuring the nonreciprocal spin-wave propagation in terms of frequency, amplitude and most importantly group velocities using all electrical spin-wave spectroscopy. The velocities of propagating spin waves show chirality among three vectors, i.e. the film normal direction, applied field and spin-wave wavevector. By measuring the asymmetric group velocities, we extract a DMI constant of 16 µJ/m 2 which we independently confirm by Brillouin light scattering. Thickness-dependent measurements reveal that the DMI originates from the oxide interface between the YIG and garnet substrate. The interfacial DMI discovered in the ultrathin YIG films is of key importance for functional chiral magnonics as ultra-low spin-wave damping can be achieved. arXiv:1910.02599v2 [cond-mat.mtrl-sci]

Interfacial Dzyaloshinskii-Moriya interaction arising from rare-earth orbital magnetism in insulating magnetic oxides

“…Very recently, iDMI has been discovered in thin films of centrosymmetric insulating iron garnets [23][24][25] , an important class of low-damping magnetic oxides in which its presence had gone undetected for decades despite their ubiquity in magnetics research. Experimental observations of homochiral Néel DWs 23,24,26 and topological Hall-like signals 27,28 in thin-film rare-earth (RE) iron garnets (REIGs) at room temperature suggest that spin-orbit-driven phenomena thought to be restricted to metallic systems might manifest more broadly in insulating magnetic oxides.…”

Probing the Source of the Interfacial Dzyaloshinskii-Moriya Interaction Responsible for the Topological Hall Effect in Metal/Tm3Fe5OLee1, Ahmed2, Flores3 et al. 2020Phys. Rev. Lett.463392View full textAdd to dashboardCite

“…Recently, signatures of topological spin textures in Pt/Tm 3 Fe 5 O 12 (TmIG) bilayers have been detected by the topological Hall effect (THE), 11,12 where a spin current is generated in the HM via the spin Hall effect (SHE) and used to detect the FMI magnetization 13,14 and topological spin textures such as skyrmions. However, there are debates in the field on whether the main source of interfacial DMI stems from the HM/FMI interface 11,12 or the FMI/substrate interface, [15][16][17] as well as the mechanism for electrical detection of magnetic textures in HM/FMI bilayers. 11 Recent work on TmIG and Y 3 Fe 5 O 12 films with minimum thicknesses of 5 nm were studied using domain wall and spin wave propagation, which found that either the majority of DMI was generated at the FMI/substrate interface or changing the capping layer did not affect the strength of the DMI.…”

“…11 Recent work on TmIG and Y 3 Fe 5 O 12 films with minimum thicknesses of 5 nm were studied using domain wall and spin wave propagation, which found that either the majority of DMI was generated at the FMI/substrate interface or changing the capping layer did not affect the strength of the DMI. [15][16][17] Previously, 12 we reported the observation of topological Hall effect in Pt/TmIG bilayers within certain temperature (T) regions tunable by the TmIG thickness, which was termed the spin-Hall topological Hall effect (SH-THE). In this letter, we aim to uncover the source of the interfacial DMI and the mechanism for the SH-THE detection of spin textures through a systematic study of TmIG films capped with various metal films and bilayers.…”

The optical tweezer of skyrmions

“…Similar to evanescent Gaussian laser beam, the oscillating laser field also traps the skyrmion. We simulate the laser pulses 70 ps in width and period and steer the center of the laser beam on a distance 14 ffiffi ffi 2 p nm along y = x in 1.3 ns. As we see in Fig.…”

“…The mechanism of trapping of a skyrmion relies on the interaction between the electric component of the laser field and the ferroelectric polarization of the skyrmion texture. As for the specific materials, we focus on two types of materials: spin-driven single-phase multiferroics and Yttrium Iron Garnet (YIG) [11][12][13][14] . In particular, we present in addition to YIG, results for the multiferroic material Cu 2 OSeO 3 , which supports skyrmions.…”