Ferroelectric control of valleytronic nonvolatile storage in HfCl2/Sc2CO2 heterostructure

Applied Physics Letters, Journal Year: 2025, Volume and Issue: 126(12)

Published: March 1, 2025

Valleytronics, utilizing the valley degree of freedom in electrons, has potential for advancing next-generation nonvolatile storage. However, practical implementation remains challenging due to limited control over valleytronic properties. Here, we propose ferroelectric HfCl2/Sc2CO2 van der Waals heterostructure as a platform overcome these limitations, enabling tunable and behaviors. Our findings show that electric polarization state Sc2CO2 monolayer governs electronic properties heterostructures. Positive induces direct gap at valleys, functionality excitation readout via circularly polarized light, while negative results an indirect-gap, suppressing behavior. Moreover, our transport simulations further demonstrate polarization-dependent p-i-n junction with 8 nm possesses maximum tunnel electroresistance (TER) ratio 1.60 × 108% bias 0.5 eV. These provide insights into ferroelectric-controlled transitions position promising candidate energy-efficient memory storage applications.

Language: Английский

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High Throughput Discovery of 2D Ferromagnetic and Multiferroic Transition Metal Oxyhalides and Nitrogen Halides

Research Square (Research Square), Journal Year: 2025, Volume and Issue: unknown

Published: April 11, 2025

Two-dimensional (2D) transition metal oxyhalides and nitrogen-halides (TMBXs, where TM = metal, B O-group N-group elements, X halogen) have emerged as promising candidates for exploring multiferroic orders spintronic applications. In this study, we conduct a systematic first-principles high-throughput screening combined with machine learning to identify novel 2D ferromagnetic materials within TMBX family. From comprehensive dataset comprising 672 monolayers, 78 systems, of which 38 exhibit high Curie temperatures (TC ≥ 200 K), significantly expanding the known library magnetic materials. A model is developed elucidate key factors governing ferromagnetism, revealing that second-nearest neighbor exchange interaction (J2) plays dominant role in determining TC. Furthermore, discover seven ferromagnetic-ferroelectric unique polarization switching pathways. Notably, spin transport simulations using nonequilibrium Green's function formalism demonstrate exceptional filtering capabilities (~ 100 %) giant bias-dependent tunneling magnetoresistance (> 105 %). These findings deepen fundamental understanding multiferroics establish solid platform future experimental exploration development next-generation devices.

Language: Английский

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Large and Tunable Electron-Depletion-Based Voltage-Controlled Magnetic Anisotropy in the CoFeB/MgO System via Work-Function-Engineered Pt_xW_1–x Underlayers

ACS Nano, Journal Year: 2025, Volume and Issue: unknown

Published: April 14, 2025

Voltage-Controlled Magnetic Anisotropy (VCMA) effect is a promising strategy for reducing energy consumption in Random-Access Memory (MRAM) embedded applications. However, the low efficiency of VCMA poses challenges CoFeB/MgO-based MRAM. Although significant coefficients have been predicted based on electron depletion (ED) orbital population model Fe/MgO interfaces, experimental validation remains limited. Here, we demonstrate an effective and industry-compatible approach to achieving electrical-field tunable interfacial perpendicular magnetic anisotropy (PMA) enhanced coefficient by synthesizing W-based metallic alloy underlayers with varying Pt concentrations, leveraging Pt's high work function strong electronegativity. Compared pure W control devices, highest concentration achieves enhancement approximately eight times greater. Additionally, Fe 2p3/2 2p1/2 orbitals at CoFeB/MgO interface observed through binding shifts. High-resolution X-ray photoelectron spectroscopy (HR-XPS) confirms these shifts as increased energies, indicating reduced density interface. These findings suggest that MRAM devices can be controlling Fermi surface under thermal equilibrium.

Language: Английский

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Giant Nonvolatile Multistate Resistance with Fully Magnetically Controlled van der Waals Multiferroic Tunnel Junctions

Nano Letters, Journal Year: 2025, Volume and Issue: unknown

Published: May 15, 2025

Ferroelectric polarization switching in electrically controlled van der Waals multiferroic tunnel junctions (vdW-MFTJs) causes atomic migration, compromising device stability and fatigue resistance. Here, we propose fully magnetically vdW-MFTJs based on a CrBr3/MnPSe3/CrBr3 vertical heterostructure, achieving ferroelectric reversal without migration. First-principles calculations reveal that integrating PtTe2/alkali-metal (Li/Na/K)-doped/intercalated CrBr3 electrodes enables exceptional performance, with maximum tunneling magnetoresistance (TMR) of 8.1 × 105% electroresistance (TER) 2499%. Applying an external bias voltage enhances the TMR to 3.6 107% TER 9990%. A pronounced negative differential resistance (NDR) effect is observed record peak-to-valley ratio (PVR) 9.55 109% for junctions. The spin-filtering channels are flexibly by magnetization direction magnetic free layer, perfect over broad range. This work paves way experimental exploration vdW-MFTJs.

Language: Английский

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