Tailoring ferromagnetism through electrically controlled morphology

Giovanni Vinai; Federico Motti; Valentina Bonanni; Damiano Cassese; Stefano Prato; Giorgio Rossi; Giancarlo Panaccione; Piero Torelli

doi:10.1002/aelm.201900150

arXiv · 1806.05414

Tailoring ferromagnetism through electrically controlled morphology

Giovanni Vinai·Federico Motti·Valentina Bonanni·Damiano Cassese·Stefano Prato·Giorgio Rossi·Giancarlo Panaccione·Piero Torelli

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Abstract

Converse magnetoelectric coupling in artificial multiferroics is generally modelled through three possible mechanisms: charge transfer, strain mediated or ion migration. Here we demonstrate a novel and highly reliable approach, where electrically controlled morphological modifications control the ferromagnetic response of a magnetoelectric heterostructure, specifically FexMn1-x ferromagnetic films on ferroelectric PMN-PT (001) substrates. The ferroelectric PMN-PT substrates present, in correspondence to electrical switching, fully reversible morphological changes at the surface, to which correspond reproducible modifications of the ferromagnetic response of the FexMn1-x films. Topographic analysis by atomic force microscopy shows the formation of surface cracks after application of a positive electric field up to 6 kV/cm, which disappear after application of negative voltage of the same amplitude. In-operando x-ray magnetic circular dichroic spectroscopy at Fe edge in FexMn1-x layers shows local variations of dichroic signal up to a factor 2.5 as a function of the electrically-driven morphological state. These findings highlight the role of morphology and surface topography as a key aspect in magnetoelectric coupling, whose proof of electrically reversible modification of the magnetic response adds a new possibility in the design of multiferroic heterostructures with electrically controlled functionalities.

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Giovanni Vinai, Federico Motti, Valentina Bonanni, Damiano Cassese, Stefano Prato, Giorgio Rossi, Giancarlo Panaccione, Piero Torelli. 2018-06-14. Tailoring ferromagnetism through electrically controlled morphology. https://doi.org/10.1002/aelm.201900150

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