Switching on superferromagnetism

A. Arora (1) , L. C. Phillips (2) , P. Nukala (3) , M. Ben Hassine (3) , A. Ünal (1) , B. Dkhil (3) , Ll. Balcells (4) , O. Iglesias (5) , A. Barthelemy (2) , F. Kronast (1) , Manuel Bibes (2) , S. Valencia (1)

1 HZB - Helmholtz-Zentrum Berlin für Materialien und Energie GmbH = Helmholtz Centre Berlin for Materials and Energy = Centre Helmholtz de Berlin pour les matériaux et l'énergie
2 Laboratoire Albert Fert (ex-UMPhy Unité mixte de physique CNRS/Thales)
3 SPMS - Laboratoire Structures, Propriétés et Modélisation des solides
4 ICMAB - Institut de Ciència de Materials de Barcelona
5 University of Barcelona

Recent results in electric field control of magnetism have paved the way for the design of new magnetic and spintronic devices with enhanced and novel functionalities and low power consumption. Among the diversity of reported magnetoelectric effects, the possibility of switching on and off long-range ferromagnetic ordering close to room temperature stands out. Its binary character opens up the avenue for its implementation in magnetoelectric data storage devices. Here we show the possibility to locally switch on superferromagnetism in a wedge-shaped polycrystalline FE thin film deposited on top of ferroelectric and ferroelastic BaTiO 3 substrate. A superparamagnetic to superferromagnetic transition is observed for confined regions for which a voltage applied to the ferroelectric substrate induces a sizable strain. We argue that electric field-induced changes of magnetic anisotropy lead to an increase of the critical temperature separating the two regimes so that superparamagnetic regions develop collective long-range superferromagnetic behaviour.

Domaines: Matière Condensée [cond-mat]

A. Arora, L. C. Phillips, P. Nukala, M. Ben Hassine, A. Ünal, et al.. Switching on superferromagnetism. Physical Review Materials, 2019, 3 (2), ⟨10.1103/PhysRevMaterials.3.024403⟩. ⟨hal-02292555⟩