Browsing by Author "Heron, J. T."

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Electric-Field-Induced Magnetization Reversal in a Ferromagnet-Multiferroic Heterostructure
(2011-11-14)
Heron, J. T.
;
Trassin, M.
;
Ashraf, K.
;
Gajek, M.
;
He, Q.
A reversal of magnetization requiring only the application of an electric field can lead to low-power spintronic devices by eliminating conventional magnetic switching methods. Here we show a nonvolatile, room temperature magnetization reversal determined by an electric field in a ferromagnet-multiferroic system. The effect is reversible and mediated by an interfacial magnetic coupling dictated by the multiferroic. Such electric-field control of a magnetoelectric device demonstrates an avenue for next-generation, low-energy consumption spintronics.
Electrically controllable spontaneous magnetism in nanoscale mixed phase multiferroics
(2011-03-01)
He, Q.
;
Chu, Y. -H.
;
Heron, J. T.
;
Yang, S. Y.
;
Liang, W. I.
Magnetoelectrics and multiferroics present exciting opportunities for electric-field control of magnetism. However, there are few room-temperature ferromagnetic-ferroelectrics. Among the various types of multiferroics the bismuth ferrite system has received much attention primarily because both the ferroelectric and the antiferromagnetic orders are quite robust at room temperature. Here we demonstrate the emergence of an enhanced spontaneous magnetization in a strain-driven rhombohedral and super-tetragonal mixed phase of BiFeO(3). Using X-ray magnetic circular dichroism-based photoemission electron microscopy coupled with macroscopic magnetic measurements, we find that the spontaneous magnetization of the rhombohedral phase is significantly enhanced above the canted antiferromagnetic moment in the bulk phase, as a consequence of a piezomagnetic coupling to the adjacent tetragonal-like phase and the epitaxial constraint. Reversible electric-field control and manipulation of this magnetic moment at room temperature is also shown.
Microscopic Origin of the Giant Ferroelectric Polarization in Tetragonal-like BiFeO(3)
(2011-09-29)
Zhang, J. X.
;
He, Q.
;
Trassin, M.
;
Luo, W.
;
Yi, D.
We report direct experimental evidence for a room-temperature, similar to 130 mu C/cm(2) ferroelectric polarization from the tetragonal-like BiFeO(3) phase. The physical origin of this remarkable enhancement of ferroelectric polarization has been investigated by a combination of x-ray absorption spectroscopy, scanning transmission electron microscopy, and first principles calculations. A large strain-induced Fe-ion displacement relative to the oxygen octahedra, combined with the contribution of Bi 6s lone pair electrons, is the mechanism driving the large ferroelectric polarization in this tetragonal-like phase.
Microscopic Origin of the Giant Ferroelectric Polarization in Tetragonal-like BiFeO3
(2011-09-29)
Zhang, J. X.
;
He, Q.
;
Trassin, M.
;
Luo, W.
;
Yi, D.
We report direct experimental evidence for a room-temperature, similar to 130 mu C/cm(2) ferroelectric polarization from the tetragonal-like BiFeO3 phase. The physical origin of this remarkable enhancement of ferroelectric polarization has been investigated by a combination of x-ray absorption spectroscopy, scanning transmission electron microscopy, and first principles calculations. A large strain-induced Fe-ion displacement relative to the oxygen octahedra, combined with the contribution of Bi 6s lone pair electrons, is the mechanism driving the large ferroelectric polarization in this tetragonal-like phase.