Magnetoelectric coupling and spin-dependent tunneling in Fe/PbTiO3/Fe multiferroic heterostructure with a Ni monolayer inserted at one interface

Abstract

We report on first-principles calculations of a Ni monolayer inserted at one interface in the epitaxial Fe/PbTiO3/Fe multiferroic heterostructure, focusing on the magnetoelectric coupling and the spin-dependent transport properties. The results of magnetoelectric coupling calculations reveal an attractive approach to realize cumulative magnetoelectric effects in the ferromagnetic/ferroelectric/ferromagnetic superlattices. The underlying physics is attributed to the combinations of several different magnetoelectric coupling mechanisms such as interface bonding, spin-dependent screening, and different types of magnetic interactions. We also demonstrate that inserting a Ni monolayer at one interface in the Fe/PbTiO3/Fe multiferroic tunnel junction is an efficient method to produce considerable tunneling electroresistance effect by modifying the tunnel potential barrier and the interfacial electronic structure. Furthermore, coexistence of tunneling magnetoresistance and tunneling electroresistance leads to the emergence of four distinct resistance states, which can be served as a multistate-storage device. The complicated influencing factors including bulk properties of the ferromagnetic electrodes, decay rates of the evanescent states in the tunnel barrier, and the specific interfacial electronic structure provide us promising opportunities to design novel multiferroic tunnel junctions with excellent performances.

Predictive modelling of ferroelectric tunnel junctions

“…54,57,58 In the case of ferroelectrics, the CBS has been calculated for BTO 20,23,52,59 and PTO. [60][61][62][63] The results show that there are multiple decay rates in the barrier for propagating states with different symmetry. The largest contribution to the transmission is expected from the bands that have lowest decay rates.…”

“…It is evident from Figure 4c that, although features in the transmission distribution look similar for the two polarisation states, there is a notable difference in the overall contrast, indicating a sizable reduction in the total conductance and thus a large TER effect when polarisation is switched from pointing towards the RuO 2 /BaO interface to the TiO 2 /BaO interface (see section 'Interface termination' for further details). Full transport calculations have been carried out for FTJs featuring the perovskite ferroelectrics BTO 20,23,59 and PTO, 63 as well as organic ferroelectric barriers. 53,70 Effects of interface termination and interlayer Interface termination.…”

“…A number of first-principles calculations have been performed for different MFTJs to elaborate these conclusions. 23,59,63,70,91 One of the important outcomes of these calculations is the demonstrated connection between the interfacial magnetoelectric effect and the ferroelectrically controlled TMR effect. 92 The reversible electric field induced by the ferroelectric polarisation is predicted to modify the magnetic structure of an adjacent ferromagnet.…”

Prospects of spintronics based on 2D materials

“…It is crucial but a challenge to fully understand the physics underlying these phenomena. It is noted that there has been a surge of first‐principles studies on these topics recently . Many of the interface issues involved in the MFTJ can be modeled and studied by first‐principles methods.…”

Long‐Range Nonvolatile Electric Field Effect in Epitaxial Fe/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 Heterostructures

“…However, the spin‐polarized screening charge is surface confined; in the spin channel, a local nonuniform spiral spin density builds at the interface and passes over into the FM layer within the spin diffusion length. This spin spiral constitutes a magnon‐driven ME interaction that has a substantial effect on the magnetization dynamics of FM layers with thicknesses as large as tens of nanometers . Therefore, the spin diffusion length is an important parameter in the magnon‐driven ME coupling process that occurs at the interfaces of FM/FE heterostructures .…”