Browsing by Author "Xie, Shuhong"

Now showing 1 - 2 of 2

Deterministic, Reversible, and Nonvolatile Low-Voltage Writing of Magnetic Domains in Epitaxial BaTiO3/Fe3O4 Heterostructure
(2018-09-01)
Zhong, Gaokuo
;
An, Feng
;
Bitla, Yugandhar
;
Wang, Jinbin
;
Zhong, Xiangli
The ability to electrically write magnetic bits is highly desirable for future magnetic memories and spintronic devices, though fully deterministic, reversible, and nonvolatile switching of magnetic moments by electric field remains elusive despite extensive research. In this work, we develop a concept to electrically switch magnetization via polarization modulated oxygen vacancies, and we demonstrate the idea in a multiferroic epitaxial heterostructure of BaTiO3/Fe3O4 fabricated by pulsed laser deposition. The piezoelectricity and ferroelectricity of BaTiO3 have been confirmed by macro- and microscale measurements, for which Fe(3)O(4 )serves as the top electrode for switching the polarization. X-ray absorption spectroscopy and X-ray magnetic circular dichroism spectra indicate a mixture of Fe2+ and Fe3+ at O-h sites and Fe3+ at T-d sites in Fe3O4, while the room-temperature magnetic domains of Fe3O4 are revealed by microscopic magnetic force microscopy measurements. It is demonstrated that the magnetic domains of Fe(3)O(4 )can be switched by not only magnetic fields but also electric fields in a deterministic, reversible, and nonvolatile manner, wherein polarization reversal by electric field modulates the oxygen vacancy distribution in Fe3O4, and thus its magnetic state, making it attractive for electrically written magnetic memories.
Piezoelectric and piezomagnetic force microscopies of multiferroic BiFeO3-LiMn2O4 heterostructures
(2014-08-14)
Eshghinejad, Ahmad
;
Liang, Wen-I.
;
Chen, Qian Nataly
;
Ma, Feiyue
;
Liu, Yuanming
BiFeO3-LiMn2O4 (BFO-LMO) heterostructures were fabricated via pulsed laser deposition, and their ferroelectric and ferromagnetic properties were probed by magnetic force microscopy (MFM), piezoresponse force microscopy (PFM), and the newly developed piezomagnetic force microscopy (PmFM). MFM imaging shows no clear distinction between BFO and LMO phases, while PFM and PmFM mappings clearly distinguish LMO nanopillars from BFO matrix. Linear piezoelectric and piezomagnetic responses have been observed in both phases, with the effects more prominent in BFO. The strong piezomagnetic response in BFO is believed to arise from Mn doping, while piezoelectric-like response of LMO is attributed to ionic activities as well as vertical geometry of the heterostructure. The limitation of global excitation of PmFM is also discussed. (C) 2014 AIP Publishing LLC.