# Non-equilibrium Green's Function and First Principle Approach to Modeling of Multiferroic Tunnel Junctions

## TL;DR

This paper presents a comprehensive multi-physics modeling framework for multiferroic tunnel junctions using NEGF, Landau-Khalatnikov, and LLG equations, validated by experimental data and analyzing device parameter effects.

## Contribution

It introduces a novel integrated simulation approach combining quantum transport, ferroelectric, and magnetic dynamics for MFTJs, filling a gap in multi-physics studies.

## Key findings

- Simulation results agree with experimental data.
- Analysis of TER and TMR dependence on device parameters.
- First-principles estimates of electrode screening lengths.

## Abstract

Recently, multiferroic tunnel junctions (MFTJs) have gained significant spotlight in the literature due to its high tunneling electro-resistance together with its non-volatility. In order to analyze such devices and to have insightful understanding of its characteristics, there is a need for developing a multi-physics modeling and simulation framework. The simulation framework discussed in this paper is motivated by the scarcity of such multi-physics studies in the literature. In this study, a theoretical analysis of MFTJs is demonstrated using self-consistent analysis of spin-based non-equilibrium Green's function (NEGF) method to estimate the tunneling current, Landau-Khalatnikov (LK) equation to model the ferroelectric polarization dynamics, together with landau-Lifshitz-Gilbert's (LLG) equations to capture the magnetization dynamics. The spin-based NEGF method is equipped with a magnetization dependent Hamiltonian that eases the modeling of the tunneling electro-resistance (TER), tunneling magneto-resistance (TMR), and the magnetoelectric effect (ME) in MFTJs. Moreover, we apply the first principle calculations to estimate the screening lengths of the MFTJ electrodes that are necessary for estimation of tunneling current. The simulation results of the proposed framework are in good agreement with the experimental results. Finally, a comprehensive analysis of TER and TMR of MFTJs and their dependence on various device parameters is illustrated.