Synthetic Antiferromagnetic Coupling Between Ultrathin Insulating Garnets

Abstract

The use of magnetic insulators is attracting a lot of interest due to a rich variety of spindependent phenomena with potential applications to spintronic devices. Here we report ultrathin yttrium iron garnet (YIG) / gadolinium iron garnet (GdIG) insulating bilayers on gadolinium iron garnet (GGG). From spin Hall magnetoresistance (SMR) and X-ray magnetic circular dichroism measurements, we show that the YIG and GdIG magnetically couple antiparallel even in moderate in-plane magnetic fields. The results demonstrate an allinsulating equivalent of a synthetic antiferromagnet in a garnet-based thin film heterostructure and could open new venues for insulators in magnetic devices. As an example, we demonstrate a memory element with orthogonal magnetization switching that can be read by SMR.

Role of gallium diffusion in the formation of a magnetically dead layer at the Y3Fe5O12/Gd3Ga5Korovin1, Bursian2, Lutsev3 et al. 2018Phys. Rev. Materials372120View full textAdd to dashboardCite

“…The magnetization of the transition layer drops gradually towards the YIG/GGG interface synchronously with the Ga-Fe substitution. In contrast to the recent works [16,38], we have not observed any antiparallel magnetic moment at the interfacial region at low temperatures. The different magnetic properties of the interface region could be the result of a different way of YIG film preparation: while we grow the film in one stage, the authors of Refs.…”

Low damping and microstructural perfection of sub-40nm-thin yttrium iron garnet films grown by liquid phase epitaxy

“…However, no extended interdiffusion layer was observed at the film/substrate interface for our LPE films, so that the presence of a 'separate, abrupt' gadolinium iron garnet interface layer, as reported by Ref. [98], is not expected. Therefore, due to possible interdiffusion effects at temperatures of about 860°C, a gradual reduction of M s at a postulated interface layer could be the reason for the observed low saturation value for the thinnest LPE film, listed in Tab.…”

“…4(h). In addition, the Gd diffusion in YIG films, as discussed for RF-magnetron sputtered [76,99] or PLD films [98], could lead to the incorporation of paramagnetic ions into the diamagnetic rare earth sublattice sites, which would also alter the magnetization [98]. However, no extended interdiffusion layer was observed at the film/substrate interface for our LPE films, so that the presence of a 'separate, abrupt' gadolinium iron garnet interface layer, as reported by Ref.…”

“…One reports about a 5-7 nm deep Ga penetration found in laser-MBE films [75]. Another group found a Ga penetration throughout a 13-nm-thin PLD film [98]. In these cases, high-temperature film growth above 850°C or prolonged post-annealing at temperatures of 850°C could promote such diffusion processes.…”

Topological spin Hall effects and tunable skyrmion Hall effects in uniaxial antiferromagnetic insulators

“…44,47 Recently, experimental work has demonstrated antiferromagnetic coupling between ultrathin bilayers of yttrium iron garnet and gadolinium iron garnet (GdIG). 62 This realization of an insulating, two-dimensional synthetic antiferromagnet would be an ideal system for testing the topological spin Hall effect we described in this paper.…”