2D Multiferroicity with Ferroelectric Switching Induced Spin-Constrained Photoelectricity

Detoxification effect of sodium thiosulfate on cadmium poisoning in Litopenaeus vannamei and the mechanisms of intestinal flora regulation

Cadmium (Cd) is currently one of the heavy metals with the highest environmental toxicity impact. Sodium thiosulfate (Na2S2O3) is a commonly used heavy metal detoxification drug in clinical practice, however, it has not been used for Cd detoxification of Litopenaeus vannamei. The present study used exposure of L. vannamei to 150 μg/L of Cd while mitigating in the addition of 75 μg/L of Na2S2O3 for 28 days. The goal was to study the detoxifying effect of Na2S2O3 on L. vannamei poisoning and its role in intestinal flora. The results showed that the growth of Cd group was inhibited, and the growth rate and weight gain of Cd + ST group were greater than that of Cd group. The function and structure of L. vannamei intestinal microorganisms were significantly changed under Cd stress. This work reveals that Na2S2O3 can mitigate the damage caused by this concentration to L. vannamei to a certain extent.

Strain- and Electron Doping-Induced In-Plane Spin Orientation at Room Temperature in Single-Layer CrTe2

Ferromagnets with a Curie temperature surpassing room temperature (RT) are highly sought after for advancing planar spintronics. The ultrathin CrTe2 is proposed as a promising two-dimensional (2D) ferromagnet with a Curie temperature above 300 K. However, its single-layer film is highly susceptible to specific external perturbations, leading to variable magnetic features depending on the environment. The magnetic ordering of single-layer CrTe2 remains a topic of debate, and experimental confirmation of ferromagnetic order at RT is still pending. In our study, we utilized molecular beam epitaxy to create a single-layer 1T-CrTe2 on bilayer graphene, demonstrating ferromagnetism above 300 K with in-plane magnetization through superconducting quantum interference devices (SQUID) measurements. Our density functional theory (DFT) calculations suggest that the ferromagnetic properties stem from epitaxial strain, which increases the distance between adjacent Cr atoms within the layer by about 1.6% and enhances the Cr-Te-Cr angle by approximately 1.6°. Due to its interaction with the graphene substrate, the magnetic moment transitions from an out-of-plane to an in-plane orientation, while electronic doping exceeds 1.5 e/u.c. Combining DFT calculations with in situ scanning tunneling microscopy (STM) characterizations allowed us to determine the configuration of the CrTe2 single layer on graphene. This discovery presents the first experimental proof of ferromagnetic order in single-layer CrTe2 with a Curie temperature above RT, laying the groundwork for future applications of CrTe2 single-layer-based spintronic devices.

Laser-Induced Ultrafast Spin Injection in All-Semiconductor Magnetic CrI3/WSe2 Heterobilayer

Spin injection stands out as a crucial method employed for initializing, manipulating, and measuring the spin states of electrons, which are fundamental to the creation of qubits in quantum computing. However, ensuring efficient spin injection while maintaining compatibility with standard semiconductor processing techniques is a significant challenge. Herein, we demonstrate the capability of inducing an ultrafast spin injection into a WSe2 layer from a magnetic CrI3 layer on a femtosecond time scale, achieved through real-time time-dependent density functional theory calculations upon a laser pulse. Following the peak of the magnetic moment in the CrI3 sublayer, the magnetic moment of the WSe2 layer reaches a maximum of 0.89 μB (per unit cell containing 4 WSe2 and 1 CrI3 units). During the spin dynamics, spin-polarized excited electrons transfer from the WSe2 layer to the CrI3 layer via type-II band alignment. The large spin splitting in conduction bands and the difference in the number of spin-polarized local unoccupied states available in the CrI3 layer lead to a net spin in the WSe2 layer. Furthermore, we confirmed that the number of available states, the spin-flip process, and the laser pulse parameters play important roles during the spin injection process. This work highlights the dynamic and rapid nature of spin manipulation in layered all-semiconductor systems, offering significant implications for the development and enhancement of quantum information processing technologies.

Robust Magnetoelectric Coupling in FeTiO3/Ga2O3 Non-van der Waals Heterostructures

Magnetoelectric coupling represents a significant breakthrough for next-generation electronics, offering the ability to achieve nonvolatile magnetic control via electrical means. In this comprehensive investigation, leveraging first-principles calculations, we unveil a robust magnetoelectric coupling within multiferroic heterostructures (HSs) by ingeniously integrating a non-van der Waals (non-vdW) magnetic FeTiO3 monolayer with the ferroelectric (FE) Ga2O3. Diverging from conventional van der Waals (vdW) multiferroic HSs, the magnetic states of the FeTiO3 monolayer can be efficiently toggled between ferromagnetic (FM) and antiferromagnetic (AFM) configurations by reversing the polarization of the Ga2O3 monolayer. This intriguing phenomenon arises from polarization-dependent substantial interlayer electron transfers and the interplay between superexchange and direct-exchange magnetic couplings of the iron atoms. The carrier-mediated interfacial interactions induce crucial shifts in Fermi level positions, decisively imparting distinct electronic characteristics near the Fermi level of composite systems. These novel findings offer exciting prospects for the future of magnetoelectric technology.

Nonvolatile switchable half-metallicity and magnetism in the MXene Hf2MnC2O2/Sc2CO2 multiferroic heterostructure

Nonvolatile electrical control of two-dimensional (2D) van der Waals (vdW) magnetism is important for spintronic devices. Here, using first-principles calculations, we systematically investigated the magnetic properties of the MXene Hf2MnC2O2 combined with the ferroelectric MXene Sc2CO2. When flipping the electric polarization of Sc2CO2, a transition between a semiconductor and a half-metal occurs in the Hf2MnC2O2 monolayer. Moreover, the ferromagnetic exchange parameter J1 can be enhanced to 9.67 meV under polarized P↑ of Sc2CO2, much larger than those of the pristine Hf2MnC2O2 monolayer and Hf2MnC2O2/Sc2CO2-P↓. In addition, the easy magnetization axis of the Hf2MnC2O2 monolayer is also dependent on the polarization orientation of Sc2CO2. Our results indicate a multiferroic heterostructure based on MXenes, offering an effective way for obtaining nonvolatile electrical control of electronic and magnetic properties.

Fully Electrically Controlled van der Waals Multiferroic Tunnel Junctions

The fully electrical control of the magnetic states in magnetic tunnel junctions is highly pursued for the development of the next generation of low-power and high-density information technology. However, achieving this functionality remains a formidable challenge at present. Here we propose an effective strategy by constructing a trilayer van der Waals multiferroic structure, consisting of CrI3-AgBiPSe6 and Cr2Ge2Te6-In2Se3, to achieve full-electrical control of multiferroic tunnel junctions. Within this structure, two different magnetic states of the magnetic bilayers (CrI3/Cr2Ge2Te6) can be modulated and switched in response to the polarization direction of the adjacent ferroelectric materials (AgBiPSe6/In2Se3). The intriguing magnetization reversal is mainly attributed to the polarization-field-induced band structure shift and interfacial charge transfer. On this basis, we further design two multiferroic tunnel junction devices, namely, graphene/CrI3-AgBiPSe6/graphene and graphene/Cr2Ge2Te6-In2Se3/graphene. In these devices, good interfacial Ohmic contacts are successfully obtained between the graphene electrode and the heterojunction, leading to an ultimate tunneling magnetoresistance of 9.3 × 106%. This study not only proposes a feasible strategy and identifies a promising candidate for achieving fully electrically controlled multiferroic tunnel junctions but also provides insights for designing other advanced spintronic devices.

Interlayer coupling controlled electronic and magnetic properties of two-dimensional VOCl2/PtTe2 van der Waals heterostructure

The coupling of hetero monolayers into van der Waals (vdW) heterostructures has become an effective way to obtain tunable physical and chemical properties of two dimensional (2D) materials. In this work, based on first principles calculations, we systematically explore the electronic and magnetic properties of a 2D VOCl2/PtTe2 heterostructure. Our results indicate that the ground state of the VOCl2/PtTe2 heterostructure is a ferromagnetic (FM) metal with large magnetic anisotropy energy, among which, the VOCl2 "sublayer" shows FM half metallic properties while the PtTe2 "sublayer" shows nonmagnetic metallic properties. The Curie temperature (TC) of VOCl2/PtTe2 is 111 K. Moreover, the FM-antiferromagnetic (AFM) phase transition can be obtained under biaxial strain. Our work provides an effective way to improve the performance of 2D monolayers in nano-electronic devices.

Electron transport, ferroelectric, piezoelectric and optical properties of two-dimensional In2Te3: a first-principles study

Two-dimensional (2D) materials have garnered significant interest in the fields of optoelectronics and electronics due to their unique and diverse properties. In this work, the electron transport, ferroelectric, piezoelectric, and optical properties of 2D In2Te3 were systematically investigated using first-principles based on density functional theory. The analysis of the phonon spectrum and elastic modulus of the Born effective criterion indicates that the structure of the novel 2D In2Te3 is dynamically stable. The calculation results show that 2D In2Te3 exhibits a carrier mobility as high as 3680.99 cm2 V-1 s-1 (y direction), a high in-plane polarization of 2.428 × 10-10 C m-1, and an excellent ferroelectric phase transition barrier (52.847 meV) and piezoelectric properties (e11 = 1.52 × 10-10 C m-1). The higher carrier mobility is attributed to the band degeneracy and small carrier effective mass. In addition, biaxial strain is an effective way to modulate the band gap and optical properties of 2D In2Te3. These properties indicate that 2D In2Te3 is a promising candidate material for flexible electronic devices and ferroelectric photovoltaic devices.

The effect of switchable electronic polarization states on the electronic properties of two-dimensional multiferroic TMBr2/Ga2SSe2 (TM = V-Ni) heterostructures

Multiferroic van der Waals (vdW) heterostructures (HSs) prepared by combining different ferroic materials offer an exciting platform for next-generation nanoelectronic devices. In this work, we investigate the magnetoelectric coupling properties of multiferroic vdW HSs consisting of a magnetic TMBr2 (TM = V-Ni) monolayer and a ferroelectric Ga2SSe2 monolayer using first-principles theory calculations. It is found that the magnetic orderings in the magnetic TMBr2 layers are robust and the band alignment of these TMBr2/Ga2SSe2 HSs can be altered by reversing the polarization direction of the ferroelectric layer. Among them, VBr2/Ga2SSe2 and FeBr2/Ga2SSe2 HSs can be switched from a type-I to a type-II semiconductor, which allows the generation of spin-polarized and unpolarized photocurrent. Besides, CrBr2/Ga2SSe2, CoBr2/Ga2SSe2 and NiBr2/Ga2SSe2 exhibit a type-II band alignment in reverse ferroelectric polarization states. Moreover, the magnetic configuration and band alignment of these TMBr2/Ga2SSe2 HSs can be further modulated by applying an external strain. Our findings suggest the potential of TMBr2/Ga2SSe2 HSs in 2D multiferroic and spintronic applications.

Giant tunneling magnetoresistance in two-dimensional magnetic tunnel junctions based on double transition metal MXene ScCr2C2F2

Two-dimensional (2D) transition metal carbides (MXenes) with intrinsic magnetism and half-metallic features show great promising applications for spintronic and magnetic devices, for instance, achieving perfect spin-filtering in van der Waals (vdW) magnetic tunnel junctions (MTJs). Herein, combining density functional theory calculations and nonequilibrium Green's function simulations, we systematically investigated the spin-dependent transport properties of 2D double transition metal MXene ScCr₂C₂F₂-based vdW MTJs, where ScCr₂C₂F₂ acts as the spin-filter tunnel barriers, 1T-MoS₂ acts as the electrode and 2H-MoS₂ as the tunnel barrier. We found that the spin-up electrons in the parallel configuration state play a decisive role in the transmission behavior. We found that all the constructed MTJs could hold large tunnel magnetoresistance (TMR) ratios over 9 × 10⁵%. Especially, the maximum giant TMR ratio of 6.95 × 10⁶% can be found in the vdW MTJ with trilayer 2H-MoS₂ as the tunnel barrier. These results indicate the potential for spintronic applications of vdW MTJs based on 2D double transition metal MXene ScCr₂C₂F₂.