Abstract
The structural and magnetic properties of LaMnO3/LaFeO3 (LMO/LFO) heterostructures are characterized using a combination of scanning transmission electron microscopy, electron energy-loss spectroscopy, bulk magnetometry, and resonant x-ray reflectivity. Unlike the relatively abrupt interface when LMO is deposited on top of LFO, the interface with reversed growth order shows significant cation intermixing of Mn3+ and Fe3+, spreading ∼8 unit cells across the interface. The asymmetric interfacial chemical profiles result in distinct magnetic properties. The bilayer with abrupt interface shows a single magnetic hysteresis loop with strongly enhanced coercivity, as compared to the LMO plain film. However, the bilayer with intermixed interface shows a step-like hysteresis loop, associated with the separate switching of the “clean” and intermixed LMO sublayers. Our study illustrates the key role of interfacial chemical profile in determining the functional properties of oxide heterostructures.
Highlights
Controlling the magnetic interactions across heterointerfaces play a central role in spintronics [1]
A well-known phenomenon related to the interfacial magnetic coupling is exchange bias (EB), which usually occurs in field-cooled ferromagnetic/antiferromagnetic systems [6]
The LaMnO3/ LaFeO3 (LMO/LFO) bilayers were fabricated on TiO2-terminated SrTiO3 (001) substrates using Pulsed laser deposition (PLD), in situ monitored by reflection high energy electron diffraction (RHEED)
Summary
Controlling the magnetic interactions across heterointerfaces play a central role in spintronics [1]. A well-known phenomenon related to the interfacial magnetic coupling is exchange bias (EB), which usually occurs in field-cooled ferromagnetic/antiferromagnetic systems [6]. The antiferromagnetic spin axis aligns perpendicular to the ferromagnetic spins to minimize the interfacial spin frustration, as revealed at La0.7Sr0.3MnO3/La(Sr)FeO3 interfaces [8,9,10]. Such spin-flop coupling is unable to induce EB, but only increases HC, while extrinsic disorders (interface roughness, for example) can create random fields acting on the ferromagnetic spins and cause EB [11,12]. It has been reported that the orbital hybridization and superexchange interaction between Mn and Fe at the interface of La2/3Sr1/
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