Unveiling structural, chemical and magnetic interfacial peculiarities in ε-Fe2O3/GaN (0001) epitaxial films

Abstract

The metastable ε-Fe2O3 is known to be the most intriguing ferrimagnetic and multiferroic iron oxide phase exhibiting a bunch of exciting physical properties both below and above room temperature. The present paper unveils the structural and magnetic peculiarities of a few nm thick interface layer discovered in these films by a number of techniques. The polarized neutron reflectometry data suggests that the interface layer resembles GaFeO3 in composition and density and is magnetically softer than the rest of the ε-Fe2O3 film. While the in-depth density variation is in agreement with the transmission electron microscopy measurements, the layer-resolved magnetization profiles are qualitatively consistent with the unusual wasp-waist magnetization curves observed by superconducting quantum interference device magnetometry. Interestingly a noticeable Ga diffusion into the ε-Fe2O3 films has been detected by secondary ion mass spectroscopy providing a clue to the mechanisms guiding the nucleation of exotic metastable epsilon ferrite phase on GaN at high growth temperature and influencing the interfacial properties of the studied films.

Role of gallium diffusion in the formation of a magnetically dead layer at the Y3Fe5O12/Gd3Ga5Korovin1, Bursian2, Lutsev3 et al. 2018Phys. Rev. Materials452130View full textAdd to dashboardCite

“…While Y tends to extend farther into GGG than Fe, it can be also due to an instrumental effect. The observed Ga/Fe concentration profile behavior resembles that reported by Ukleev et al [24] for the εFe 2 O 3 /GaN system, where the partial substitution of iron by gallium in the interface region was demonstrated by SIMS.…”

Ultrathin regime growth of atomically flat multiferroic gallium ferrite films with perpendicular magnetic anisotropy

“…This might also explain the initial 3D mode growth, where totally relaxed GFO islands coalesce while the deposition proceeds to obtain a flat surface. Such a 3D-to-2D metamorphic epitaxial growth [32] mechanism has already been reported for SrRuO 3 [33] onto STO and for ε − Fe 2 O 3 [34,35], which is isomorphic to GFO. In both cases, the initial 3D growth mode was related to the large lattice mismatch between substrate and thin film.…”

Magnetic Structure of Ion-Beam Imprinted Stripe Domains Determined by Neutron Scattering

“…The technique is applicable to a wide range of material classes (See for example References [31,[34][35][36][37][38][39] and references therein). For example, magnetization vector distributions along the surface normal or along the sample plane can be obtained from thin-film systems comprising exchange coupled hard-soft magnetic hybrid materials and phase separation [36,[65][66][67], exchange coupled magnetic multilayers [38,68] and non-magnetic thin film systems [31,37,69]. PNR and OSS can further be used to detect correlations among magnetic domains as a function of depth and laterally in nanoparticle systems or emerging material classes, such as topological insulator [70,71] and multiferroic nanostructures [72].…”