Full Electric Control of Exchange Bias

Abstract

We report the creation of a multiferroic field effect device with a BiFeO(3) (BFO) (antiferromagnetic-ferroelectric) gate dielectric and a La(0.7)Sr(0.3)MnO(3) (LSMO) (ferromagnetic) conducting channel that exhibits direct, bipolar electrical control of exchange bias. We show that exchange bias is reversibly switched between two stable states with opposite exchange bias polarities upon ferroelectric poling of the BFO. No field cooling, temperature cycling, or additional applied magnetic or electric field beyond the initial BFO polarization is needed for this bipolar modulation effect. Based on these results and the current understanding of exchange bias, we propose a model to explain the control of exchange bias. In this model the coupled antiferromagnetic-ferroelectric order in BFO along with the modulation of interfacial exchange interactions due to ionic displacement of Fe(3+) in BFO relative to Mn(3+/4+) in LSMO cause bipolar modulation.

Polaronic Transport Induced by Competing Interfacial Magnetic Order in aLa0.7Ca0.3MnO3/BiFe

“…This state displays an exchange-bias field and magnetotransport that can be tuned by switching the FE polarization, increasing the potential for device control through interfacial coupling. However, a complete picture of the interplay between FM and AFM orders in this heterostructure has yet to be reached.Current understanding of the exchange-bias field, which arises from the interaction between FM and G-type AFM [AFMðGÞ] orders at the interface, is based on spin canting or pinning in BFO, with the assumption of negligible canting in the manganite layer [14][15][16]. However, given that the spin interaction is mutual, it is not clear why FM spins in LSMO can induce AFM spins in BFO to cant, but the reverse has not been discussed.…”

“…The combination of these materials thus has great potential for exhibiting novel phenomena by coupling different FM, AFM, and FE phases across the interface. Indeed, a new interfacial state between LSMO and BFO has been discovered experimentally and discussed theoretically [2,[14][15][16]. This state displays an exchange-bias field and magnetotransport that can be tuned by switching the FE polarization, increasing the potential for device control through interfacial coupling.…”

Magnetoelectric coupling across the interface of multiferroic nanocomposites

“…In rhombohedral Pb(Mg 1/3 Nb 2/3 ) 0. 72 Ti 0.28 O 3 (PMN-PT) single crystals with high piezoelectricity, Thiele et al [27] discovered that the T c of LSMO thin film increased by 19 K and the ME coefficient was about 6×10 −8 s m −1 , which further confirmed the effective contribution from the strain transfer across the interface on the ME coupling. In principle, mechanical-stress-controlled Mn-O bond length can be assumed as the microscopic origin of the ferromagnetic states of the LSMO thin film.…”

“…More importantly, the interfacial exchange bias can be controlled by switching the ferroelectric polarization of the multiferroic BFO. In such a heterostructure, Wu et al [71,72] demonstrated that the ferroelectric polarization could be coupled with the ferromagnetic order at BFO interface, which was used to control the magnitude of magnetic coercive field and the directions of the exchange bias as shown in Fig. 6.…”

Preparation and characterisation of epitaxial Pt/Cu/FeMn/Co thin films on (100)‐oriented MgO single crystals

“…Nowadays, they find numerous applications in magnetic storage devices, sensors and also in spintronics [1][2][3][4][5][6][7]. Nevertheless, basic phenomena are not understood so far and are still a matter of research [8][9][10][11].…”