Giant magnetoresistance and tunneling electroresistance in multiferroic tunnel junctions with 2D ferroelectrics

Abstract

Multiferroic tunneling junctions (MFTJ), composed of two magnetic electrodes separated by an ultrathin ferroelectric (FE) thin film as barrier, have received great attention in multi-functional devices. Recent theoretical and experimental...

Memory and Synaptic Devices Based on Emerging 2D Ferroelectricity

“…However, four distinct electrical states (without magnetic states) could be obtained by the polarization configuration of each 𝛼-In 2 Se 3 layer in the study. [48] TMR and TER combinations were found to have eight distinct states using different magnetization configurations of the FM in the NIBN device, as shown in Figure 27b. Having more states enables more multi-level memristors.…”

“…Chen et al calculated the performance of a Ni/bi-layer In 2 Se 3 /h-BN/Ni (NIBN) device and found enhanced TER and TMR by inserting h-BN as a buffer layer (Figure 27 (a)). [48] For conventional MFTJs, four resistance states were implemented using the polarization and magnetization directions of the FE and FM, respectively. However, four distinct electrical states (without magnetic states) could be obtained by the polarization configuration of each 𝛼-In 2 Se 3 layer in the study.…”

“…Then, in Sections 3, 4, and 5, the three types of devices based on 2D ferroelectric materials will be discussed in detail. We note that the first (FeFET) and third (FTJ) types of devices have also employed conventional 3D ferroelectric materials (e.g., perovskite oxide materials), [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] but the second type (active ferroelectric channel devices) is being newly developed with emerging 2D ferroelectric materials. [29,[50][51][52][53][54][55][56][57][58][59][60][61][62] In each chapter, synaptic device applications and their current status are reviewed for each device type.…”

Large tunneling magnetoresistance in van der Waals magnetic tunnel junctions based on FeCl2films with interlayer antiferromagnetic couplings

“…[12][13][14][15] With the rapid growth of two-dimensional (2D) materials, van der Waals (vdW) MTJs with high TMR ratios become promising candidates for spintronic devices. [16][17][18][19][20][21][22] The vdW heterostructure consisting of an atomically thin BN layer acting as a tunnel barrier and two Fe 3 GeTe 2 crystals on both sides has a geometry-associated switching field and shows minimum (maximum) tunneling resistance when the magnetization directions of the two electrodes are parallel (antiparallel), but it is very limited with a minor TMR ratio of 120% at 4.2 K. 23 One of the most remarkable findings is the CrI 3 -based MTJ, where the few-layer CrI 3 with AFM/FM states results in high/ low resistance states of the device. This type of device in which a 2D vdW magnetic insulator is sandwiched between two nonmagnetic conducting electrodes has bright prospects in easy operation and low-power applications.…”

Reversible Thermally Driven Phase Change of Layered In2Se3 for Integrated Photonics

“…Recently, two-dimensional (2D) In 2 Se 3 has attracted considerable attention because of the unique properties of its extraordinary ferroelectric, optoelectronic, and thermoelectric properties. − Intriguingly, In 2 Se 3 is polymorphic and possesses multiple crystalline phases, including α, α′, β, β′, γ, γ′, δ, and κ. − Moreover, the α phase possesses two different stacking sequences, i.e., hexagonal (2H) and rhombohedral (3R) structures, and the β phase possesses three different stacking sequences, i.e., trigonal (1T), 2H, and 3R structures. , These differences in stacking sequences, the bonding geometries of In/Se atoms, and the vacancy distribution geometries result in different electrical and optical characteristics. For example, α-In 2 Se 3 has a noncentrosymmetric crystal structure and both in-plane and out-of-plane ferroelectricity. − On the contrary, an antiferroelectric order and ferroelasticity were observed in β′-In 2 Se 3 . − Indeed, amorphous In 2 Se 3 and a part of crystalline phases such as 2H/3R α, 2H/3R β′, and γ are stable for 2D In 2 Se 3 at room temperature, − which provides the possibility of multilevel nonvolatile switching.…”