CN-121985730-A - Spin electronic device based on ferromagnetic metal/two-dimensional ferromagnetic half-metal heterojunction

CN121985730ACN 121985730 ACN121985730 ACN 121985730ACN-121985730-A

Abstract

The invention discloses a spin electron device based on a ferromagnetic metal/two-dimensional ferromagnetic half-metal heterojunction, which comprises a ferromagnetic metal electrode and a single-layer two-dimensional ferromagnetic half-metal material layer, wherein the ferromagnetic metal is nickel (Ni) or cobalt (Co), the two-dimensional ferromagnetic half-metal is ferrous halide FeX 2 , X=Cl, br and I, the two-dimensional ferromagnetic half-metal and the two-dimensional ferromagnetic half-metal form a heterojunction through edge contact or top contact to achieve spin injection efficiency close to 100%, and hexagonal boron nitride (h-BN) is introduced on the basis of a heterojunction structure of Ni and ferrous chloride (FeCl 2 ) to serve as a two-dimensional tunneling barrier layer, so that a Van der Waals magnetic tunnel junction device of Ni/FeCl 2 /h-BN/FeCl 2 /Ni can be constructed. The structure maintains tunneling current of complete spin polarization in parallel magnetization directions, the transmissivity is obviously reduced in anti-parallel magnetization directions, and Tunnel Magnetoresistance (TMR) exceeding 3000% can be realized. The invention realizes the effective regulation and control of spin transportation at the device level through the heterojunction structure and interface configuration design, and is suitable for spin valves, spin filters and low-power magnetic tunnel junction memories.

Inventors

GUO ZHICHENG
ZHANG SHUO
ZHUO CHENG
YIN WENYAN
ZHOU ZEKAI
XIE HAO

Assignees

浙江大学

Dates

Publication Date: 20260505
Application Date: 20260403

Claims (10)

1. A spintronic device comprising a heterojunction formed by a ferromagnetic metal electrode and a two-dimensional ferromagnetic half-metal material layer, wherein the ferromagnetic metal electrode is nickel (Ni) or cobalt (Co), and the two-dimensional ferromagnetic half-metal material is a single layer of ferrous halide FeX 2 , x=cl, br, I.
2. The spintronic device according to claim 1, characterized in that the ferromagnetic metal electrode forms a heterojunction interface with the two-dimensional ferromagnetic half-metal material layer by edge contact or top contact.
3. The spintronic device according to claim 2, characterized in that a heterojunction interface formed by top contact means, a van der waals gap exists between the ferromagnetic metal electrode and the two-dimensional ferromagnetic half-metal material layer, and interface orbital hybridization can be suppressed.
4. A spintronic device according to claim 2, characterized in that the spin down direction of the monolayer of ferrous halide material is determined by the spin polarization direction of the ferromagnetic metal electrode.
5. The spintronic device of claim 2, characterized in that interfaces form selective spin transport channels, differently oriented electron spins exhibiting different transmission characteristics at the heterojunction interface.
6. The spintronic device of claim 2, characterized in that the top contact forms a vertical spin filter structure with a spin polarization flip voltage below 0.5V.
7. The magnetic tunnel junction is characterized by comprising a ferromagnetic metal upper electrode a, a first layer of two-dimensional ferromagnetic half-metal material b, a tunneling barrier layer c, a second layer of two-dimensional ferromagnetic half-metal material d and a ferromagnetic metal lower electrode e from top to bottom, which are sequentially stacked, wherein the ferromagnetic metal upper electrode a and the ferromagnetic metal lower electrode e are the same ferromagnetic metal, ni or Co, the first layer of two-dimensional ferromagnetic half-metal material b and the second layer of two-dimensional ferromagnetic half-metal material d are both selected from single-layer FeX 2 , X=Cl, br, I, and the tunneling barrier layer c is hexagonal boron nitride (h-BN) from single-layer to three-layer.
8. The magnetic tunnel junction of claim 7 wherein the magnetic tunnel junction is comprised of nickel/single layer ferrous chloride (FeCl 2 )/1 to 3 layers of h-BN/single layer FeCl 2 /nickel stacked in sequence.
9. A non-volatile memory cell comprising a spintronic device according to any of claims 1 to 6 or a magnetic tunnel junction according to any of claims 7 to 8.
10. A memory device comprising the memory cell of claim 9.

Description

Spin electronic device based on ferromagnetic metal/two-dimensional ferromagnetic half-metal heterojunction Technical Field The invention belongs to the technical field of spintronics, and relates to a spintronic device based on a ferromagnetic metal/two-dimensional ferromagnetic half-metal heterojunction, which can realize high-polarization spin injection and tunnel magnetic resistance regulation. Background The spintronics is a novel technology for information transmission and processing by using the degree of freedom of electron spin, and different from the traditional electronics taking charges as carriers, the spintronics device can simultaneously realize low power consumption, high speed and nonvolatile memory function 【Baibich M N, Broto J M, Fert A, et al. Giant Magnetoresistance of (001)Fe/(001)Cr Magnetic Superlattices [J]. Physical Review Letters, 1988, 61(21): 2472-2475.】., wherein a spin filter and a Magnetic Tunnel Junction (MTJ) are core structures for realizing spin selective transport and logic operation, and the performance of the spintronics device mainly depends on spin polarization rate, spin holding time and interface transport characteristics. Conventional MTJ devices generally employ a metal/insulator/metal multilayer structure such as a cobalt (Co)/magnesium oxide (MgO)/Co or iron (Fe)/MgO/Fe system, which realizes a magnetoresistance effect through spin-dependent tunneling. However, such devices have problems of mismatching of conductivity, strong scattering of interface, complex preparation process, etc., which results in limited 【Schmidt G, Ferrand D, Molenkamp L W, et al. Fundamental obstacle for electrical spin injection from a ferromagnetic metal into a diffusive semiconductor [J]. Physical Review B, 2000, 62(8): R4790-R4793.】. spin injection efficiency, and in addition, the chemical reaction and interface roughness of the multilayer thin film often cause spin polarization loss, which affects the reliability of the device. With the rise of two-dimensional materials, spintronics has come to a new development opportunity. Since 2004 graphene was successfully stripped, two-dimensional transition metal chalcogenide (TMD), black phosphorus, hexagonal boron nitride (h-BN) and other systems have been widely studied 【Novoselov K S, Geim A K, Morozov S V, et al. Electric Field Effect in Atomically Thin Carbon Films [J]. Science, 2004, 306(5696): 666-669.】., especially the discovery of 2017 chromium triiodide (CrI 3) and iron germanium tellurium (Fe 3GeTe2) and other intrinsic two-dimensional ferromagnetic materials, which verifies stable ferromagnetic order under the thickness of a monoatomic layer and provides a new platform for the construction of two-dimensional spin valves and magnetic tunnel junctions 【Gong C, Li L, Li Z, et al. Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals [J]. Nature, 2017, 546(7657): 265-269.】. However, it should be noted that the intrinsic spin polarization properties of the material are not directly equivalent to the spin transport effects at the device level. In an actual device, the spin transport behavior is obviously affected by the contact mode, the interface coupling mode, the interface state distribution and other factors between the two-dimensional ferromagnetic semi-metal material and the metal electrode. Unreasonable contact configurations may introduce orbital hybridization, interface state leakage, or spin scattering, thereby diminishing the device's intrinsic spin polarization characteristics of the material. Therefore, how to realize effective regulation and control of two-dimensional ferromagnetic half-metal spin transport characteristics at the device level through reasonable heterojunction structure design is still to be further researched and perfected 【Yang H X, Hallal A, Terrade D, et al. Proximity Effects Induced in Graphene by Magnetic Insulators: First-Principles Calculations on Spin Filtering and Exchange-Splitting Gaps [J]. Physical Review Letters, 2013, 110(4): 046603.】. Based on the background, the invention provides a heterojunction system based on ferromagnetic metal and two-dimensional ferromagnetic semi-metal-single-layer ferrous halide (FeX 2, wherein X=Cl, br, I), which is proved by theoretical calculation to realize spin down transmission probability close to 100% near fermi energy and remarkably inhibit spin up channels. Specifically, the FeX 2 material shows spin-dependent transport characteristics under the regulation of the heterojunction interface, spin-down energy bands are metallic at the fermi level, and spin-up energy bands have band gaps, so that the material shows high conductivity to spin-down electrons near the fermi level, and effectively blocks the transmission of electrons in the spin-up direction. The heterojunction spin filter structure can realize excellent spin filter capability, and spin injection efficiency can be greatly improved by optimizing materials and structural c