posted on 2021-11-17, 10:29authored byXiao Chi, Rui Guo, Juxia Xiong, Lizhu Ren, Xinwen Peng, Beng Kang Tay, Jingsheng Chen
Magnetic
tunnel junctions (MTJs) with tunable tunneling magnetoresistances
(TMR) have already been proven to have great potential for spintronics.
Especially, when ferroelectric materials are used as insulating barriers,
more novel functions of MTJs can be realized due to interface magnetoelectric
coupling. Here, we demonstrate a very large ferroelectric modulation
of TMR (as high as 570% in low-resistance state) in the ferroelectric/magnetic
La0.5Sr0.5MnO3/BaTiO3 (LSMO/BTO)
junctions and find robust interfacial electronic and magnetic reconstructions
via ferroelectric polarization switching. Through electrical, magnetic,
and optical measurements combined with X-ray absorption and magnetic
circular dichroism, we reveal that the interfacial electronic and
magnetic (ferromagnetic/antiferromagnetic phase transition) reconstructions
originate from strong electromagnetic coupling between BTO and LSMO
at the interface and are driven by the modulation of hole/electron
doping at the interface of LSMO/BTO through ferroelectric polarization
switching. As a result, the ferroelectrically controlled interface
barrier height and width and spin filter effect enable a giant electrical
modulation of TMR. Our results shed new light on the intrinsic mechanisms
governing magnetoelectric coupling and offering a new route to enhance
magnetoelectric coupling for spin control in spintronic devices.