Coexistence of tunneling magnetoresistance and electroresistance at room temperature in La0.7Sr0.3MnO3/(Ba, Sr)TiO3/La0.7Sr0.3MnO3 multiferroic tunnel junctions

Abstract

Tunnel junctions composed of two ferromagnetic electrodes separated by a ferroelectric barrier were fabricated from epitaxial La0.7Sr0.3MnO3/Ba0.95Sr0.05TiO3/La0.7Sr0.3MnO3 trilayers. Typical R−H curves with sharp-switched resistance states (magnetic parallel and antiparallel) of magnetic tunnel junctions have been observed up to room temperature. After applying a poling voltage, which reverses the barrier polarization, both the parallel and antiparallel resistance states will switch to different values. Clear tunneling magnetoresistance and tunneling electroresistance, hence the four resistance states have been observed at room temperature.

Multiferroic tunnel junctions and ferroelectric control of magnetic state at interface (invited)

“…Due to these advantages, experimental efforts have been made and evidences of the four states have been demonstrated by several groups in MFTJs with (Ba, Sr)TiO 3 , BiFeO 3 , or PbZr 0.2 Ti 0.8 O 3 ferroelectric tunnel barriers. [15][16][17][18][19][20] Very recently, the realization of an epitaxial perovskite BaTiO 3 (BTO) based FTJ on silicon suggests the possibility of integrating FTJs/ MFTJs on silicon wafers, thus the integration with semiconductor electronics. 21 In addition to the capability to control electron and spin tunneling via ferromagnetic and ferroelectric polarizations in the electrode and barrier layers, the MFTJs have also been predicted to have other advantages beyond the simple addition of an MTJ with an FTJ.…”

Octonary Resistance States in La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 Multiferroic Tunnel Junctions

“…Furthermore, if we set the turning fi eld to +60 Oe (green curve in Figure 2 b The junction resistance of the MFTJ could be further manipulated by ferroelectric polarization of barrier, displaying TER effect. [21][22][23][24][25][26] For the MFTJ, the ferroelectric polarization of the BaTiO 3 barrier can be aligned downward or upward by a poling voltage of +1.5 V or −1.5 V. As shown in Figure 4 , by a series of consecutive switching of the barrier polarization, the parallel resistances between the two polarization states 1 and 4 can be switched directly. To exclude other resistance switching mechanisms such as the interfacial electrochemical modifi cation or conducting fi lament formation and rupture, [ 37,38 ] piezoresponse force microscopy has been carried out to demonstrate that the ferroelectric polarization reversal is the underlying mechanism for the TER resistive switching in our system ( Figure S3, Supporting Information).…”

“…[15][16][17] Similar to the multi ferromagnetic domain related multistates in MTJs, [12][13][14] multilevel memristor-type behavior can be obtained in ferroelectric tunnel junctions (tunnel junctions with ferroelectric barrier) as well by a partial switching of the ferroelectric domains in ferroelectric barrier. [18][19][20] [21][22][23][24][25][26][27] Combining these two mechanisms of increasing storage states, the multinary memory devices with an enhanced capacity of information storage may be achieved through integrating the features of noncollinear magnetization alignment with the ferroelectric polarization switching.…”

Fabrication and Ferroelectric Properties of BiFeO3/BaTiO3Heterostructures

“…ME coupling can also occur at FM/FE interfaces where its mechanism is mediated by strain (magnetostriction and piezoelectricity), charge (sensitivity of magnetic state on charge accumulation) or exchange bias (coupling of antiferromagnetic domain walls to ferroelectric ones) [3]. ME effect was also observed in multiferroic tunnel junctions composed of two FM electrodes separated by thin FE barrier [4]. At the atomic level it is the interface bonding which is the source of ME effect in heterostructures.…”