Epitaxial growth and ferrimagnetic behavior of MnFe2O4(111) ultrathin layers for room-temperature spin filtering

Abstract

We report on the epitaxial growth and physical properties of spinel MnFe 2 O 4 (111) thin films with thicknesses down to 2 nm. The thin films, grown on α-Al 2 O 3 (0001) single crystals or Pt(111) buffer layers by oxygen-assisted molecular beam epitaxy, exhibit high structural order with sharp interfaces and low roughness. The electrical and magnetic properties are carefully investigated and it is shown that MnFe 2 O 4 (111) ultrathin films keep an insulating and ferrimagnetic behavior at room temperature. Special attention is given to the iron/manganese valence state and the cationic ordering. X-ray absorption spectroscopy and magnetic circular dichroism measurements reveal that thin films contain mainly Fe 3+ and Mn 2+ cations, distributed predominantly in a normal spinel structure. This study proves the high potential of MnFe 2 O 4 to be used as a magnetic tunnel barrier for spin filtering applications at room temperature.

Epitaxial growth of (1 1 1)-oriented spinel CoCr2O4/Al2O3 heterostructures

“…These half order reflections are the characteristic signature of spinel thin films grown on sapphire substrate and have also been observed in other works. [23][24][25] The evolution of these RHEED images confirms that the epitaxial growth relation is CCO ð1 1 1Þ½1 1 0 jja-AlOð0 0 0 1Þ½1 1 0 0. When the first AlO is deposited onto the CCO layers, the typical spinel half orders become weaker and as the second AlO layer is deposited, the half order streaks vanish and the RHEED pattern looks closer to the substrate pattern, as displayed in Fig.…”

Photo-Fenton degradation of ammonia via a manganese–iron double-active component catalyst of graphene–manganese ferrite under visible light

“…These peaks may be respectively assigned to Fe 2p 3/2 and Fe 2p 1/2 . Three satellite peaks are also visible at the Eb of around 719.30, 732.59, and 733.49 eV, all of which indicate the presence of Fe 3+ cations [47,48]. The broadened peak of Fe 2p 1/2 (deconvoluted into 724.11 and 726.24 eV, as shown in the inset of Fig.…”

Spin waves across three-dimensional, close-packed nanoparticles

“…Magnetite core|manganese ferrite shell nanoparticles were prepared using the Sun method [23]. Magnetite (Fe 3 O 4 ) is a common choice for biomedical applications due to its bio-compatibility; the inclusion of Mn further decreases the low magnetocrystalline anisotropy of Fe 3 O 4 [24,25]. Such magnetic softening could in principle promote longer ranged inter-particle magnetic coupling.…”