Two-dimensional Magnetic Semiconductors Research Articles

CrSBr: An Air-Stable, Two-Dimensional Magnetic Semiconductor.

The discovery of magnetic order at the 2D limit has sparked new exploration of van der Waals magnets for potential use in spintronics, magnonics, and quantum information applications. However, many of these materials feature low magnetic ordering temperatures and poor air stability, limiting their fabrication into practical devices. In this Mini-Review, we present a promising material for fundamental studies and functional use: CrSBr, an air-stable, two-dimensional magnetic semiconductor. Our discussion highlights experimental research on bulk CrSBr, including quasi-1D semiconducting properties, A-type antiferromagnetic order (TN = 132 K), and strong coupling between its electronic and magnetic properties. We then discuss the behavior of monolayer and few-layer flakes and present a perspective on promising avenues for further studies on CrSBr.

Observation of the possible magnetic correction above the Curie temperature in Cr2Si2Te6 single crystals.

Intrinsic magnetic semiconductors hold great promise in the fields of fundamental magnetization and spintronics. One such semiconductor is Cr2Si2Ti6 (CST), a quasi two-dimensional (2D) magnetic semiconductor with potential applications in future magnetic devices. However, the origin of ferromagnetism in CST remains a mystery. To investigate this, ac/dc susceptibility and electronic spin resonance (ESR) measurements were conducted. Based on ac susceptibility scaling, the critical temperature (TC) for the ferromagnetic (FM) to paramagnetic (PM) phase transition was found to be ∼32.5 K, with a critical exponent of δ = 6.7 from the critical isotherm, β + γ = 1.72 from the temperature dependence of the crossover line, and γ = 1.43 from the temperature dependence of susceptibility along the same line. All critical exponents were found to be consistent with the dc magnetization scaling method. However, above and below TC, the origin of magnetism cannot be explained by a single theory. To explore the origin of abnormal magnetic critical behavior, ESR measurements were performed. Below T* ∼ 130 K, the ESR measurements revealed that the resonance field width (ΔH) tends to increase and decrease for the applied magnetic field H parallel and perpendicular to the c axis, respectively, indicating the onset of magnetic interaction even in the PM state. Meanwhile, the deviation from Curie-Weiss behavior below T* also confirmed the occurrence of magnetic correlation above the TC in CST. These observations suggest that the competition and cooperation among the direct and indirect interactions, the structural distortion and the van der Waals interaction at high temperature should be considered to investigate the origin of anomalous magnetism in CST. The present results provide valuable insights into the nature of ferromagnetism in 2D magnetic semiconductors.

Intrinsic room-temperature ferromagnetism in a two-dimensional semiconducting metal-organic framework

The development of two-dimensional (2D) magnetic semiconductors with room-temperature ferromagnetism is a significant challenge in materials science and is important for the development of next-generation spintronic devices. Herein, we demonstrate that a 2D semiconducting antiferromagnetic Cu-MOF can be endowed with intrinsic room-temperature ferromagnetic coupling using a ligand cleavage strategy to regulate the inner magnetic interaction within the Cu dimers. Using the element-selective X-ray magnetic circular dichroism (XMCD) technique, we provide unambiguous evidence for intrinsic ferromagnetism. Exhaustive structural characterizations confirm that the change of magnetic coupling is caused by the increased distance between Cu atoms within a Cu dimer. Theoretical calculations reveal that the ferromagnetic coupling is enhanced with the increased Cu-Cu distance, which depresses the hybridization between 3d orbitals of nearest Cu atoms. Our work provides an effective avenue to design and fabricate MOF-based semiconducting room-temperature ferromagnetic materials and promotes their practical applications in next-generation spintronic devices.

Proximity-Induced Interfacial Room-Temperature Ferromagnetism in Semiconducting Fe3GeTe2.

The discoveries of two-dimensional ferromagnetism and magnetic semiconductors highly enrich the magnetic material family for constructing spin-based electronic devices, but with an acknowledged challenge that the Curie temperature (Tc) is usually far below room temperature. Many efforts such as voltage control and magnetic ion doping are currently underway to enhance the functional temperature, in which the involvement of additional electrodes or extra magnetic ions limits their application in practical devices. Here we demonstrate that the magnetic proximity, a robust effect but with elusive mechanisms, can induce room-temperature ferromagnetism at the interface between sputtered Pt and semiconducting Fe3GeTe2, both of which do not show ferromagnetism at 300 K. The independent electrical and magnetization measurements, structure analysis, and control samples with Ta highlighting the role of Pt confirm that the ferromagnetism with the Tc of above 400 K arises from the Fe3GeTe2/Pt interfaces, rather than Fe aggregation or other artificial effects. Moreover, contrary to conventional ferromagnet/Pt structures, the spin current generated by the Pt layer is enhanced more than two times at the Fe3GeTe2/Pt interfaces, indicating the potential applications of the unique proximity effect in building highly efficient spintronic devices. These results may pave a new avenue to create room-temperature functional spin devices based on low-Tc materials and provide clear evidence of magnetic proximity effects by using nonferromagnetic materials.

Possible Room-Temperature Ferromagnetic Semiconductors

Magnetic semiconductors integrate the dual characteristics of magnets and semiconductors. It is difficult to manufacture magnetic semiconductors that function at room temperature. Here, we review a series of our recent theoretical predictions on room-temperature ferromagnetic semiconductors. Since the creation of two-dimensional (2D) magnetic semiconductors in 2017, there have been numerous developments in both experimental and theoretical investigations. By density functional theory calculations and model analysis, we recently predicted several 2D room-temperature magnetic semiconductors, including CrGeSe3 with strain, CrGeTe3/PtSe2 heterostructure, and technetium-based semiconductors (TcSiTe3, TcGeSe3, and TcGeTe3), as well as PdBr3 and PtBr3 with a potential room-temperature quantum anomalous Hall effect. Our findings demonstrated that the Curie temperature of these 2D ferromagnetic semiconductors can be dramatically enhanced by some external fields, such as strain, construction of heterostructure, and electric field. In addition, we proposed appropriate doping conditions for diluted magnetic semiconductors, and predicted the Cr doped GaSb and InSb as possible room-temperature magnetic semiconductors.

An Optical Spectroscopic Study of Air-Degradation of van der Waals Magnetic Semiconductor Cr2Ge2Te6

Two-dimensional (2D) magnetic semiconductors exhibit unique combination of electronic and magnetic properties, holding great promise in potential applications such as spintronics and magneto-optics. However, many of them are air-sensitive, and their properties can be significantly altered upon exposure to air. Here, we showed an optical spectroscopic investigation of the effects of air-degradation on few-layered van der Waals (vdW) magnetic semiconductor Cr2Ge2Te6. It was found that although the partially degraded few-layered Cr2Ge2Te6 showed a significant Raman redshift and a split of Eg peak at room temperature, the magneto-optic Kerr hysteresis loop can remain largely unchanged below the Curie temperature. Temperature-dependent Raman measurements further revealed characteristic blueshifts of phonon energy, which were associated with the ferromagnetic phase transition in partially degraded Cr2Ge2Te6, in agreement with Kerr measurements. Our results provide an optical spectroscopic insight into the air-instability of 2D magnetic semiconductors, and contribute to a better understanding of the relationship between phonon modes and long-range spin order at the presence of defects in ultra-thin vdW magnetic semiconductors.

Nonvolatile electrical control of spin polarization in the 2D bipolar magnetic semiconductor VSeF

Nonvolatile electrical control of spin polarization in two-dimensional (2D) magnetic semiconductors is greatly appealing toward future low-dissipation spintronic nanodevices. Here, we report a 2D material VSeF, which is an intrinsic bipolar magnetic semiconductor (BMS) featured with opposite spin-polarized valence and conduction band edges. We then propose a general nonvolatile strategy to manipulate both spin-polarized orientations in BMS materials by introducing a ferroelectric gate with proper band alignment. The spin-up/spin-down polarization of VSeF is successfully controlled by the electric dipole of ferroelectric bilayer Al2Se3, verifying the feasibility of the design strategy. The interfacial doping effect from ferroelectric gate also plays a role in enhancing the Curie temperature of the VSeF layer. Two types of spin field effect transistors, namely multiferroic memory and spin filter, are further achieved in VSeF/Al2Se3 and VSeF/Al2Se3/Al2Se3 multiferroic heterostructures, respectively. This work will stimulate the application of 2D BMS materials in future spintronic nanodevices.

Strain induced metal-semiconductor transition in two-dimensional topological half metals.

Spintronic applications of two-dimensional (2D) magnetic half metals and semiconductors are thought to be very promising. Here, we suggest a family of stable 2D materials (X= Cl, Br, and I). The monolayer exhibits an in-plane ferromagnetic (FM) ground state with a Curie temperature of 118K, which is unveiled to be a 2D Weyl half semimetal with two Weyl points of opposite chirality connected by a remarkable Fermi arc. In addition, it appears that a biaxial tensile strain can lead to a metal-semiconductor phase transition as a result of the increased anomalous Jahn-Teller distortions, which raise the degeneracy of the energy level and cause a significant energy splitting. A 10% biaxial tensile strain also increases the Curie temperature to about 159K, which originates from the enhanced Mn-Cl-Mn FM superexchange. Moreover, the metal-semiconductor transition can also be induced by a uniaxial strain. Our findings provide an idea to create 2D magnetic semiconductors through metal-semiconductor transition in half metals.

Magnetic and spin transport properties of a two-dimensional magnetic semiconductor kagome lattice Nb<sub>3</sub>Cl<sub>8</sub> monolayer

Two-dimensional semiconductor materials with intrinsic magnetism have great application prospects in realizing spintronic devices with low power consumption, small size and high efficiency. Some two-dimensional materials with special lattice structures, such as kagome lattice crystals, are favored by researchers because of their novel properties in magnetism and electronic properties. Recently, a new two-dimensional magnetic semiconductor material Nb<sub>3</sub>Cl<sub>8</sub> monolayer with kagome lattice structure was successfully prepared, which provides a new platform for exploring two-dimensional magnetic semiconductor devices with kagome structure. In this work, we study the electronic structure and magnetic anisotropy of Nb<sub>3</sub>Cl<sub>8</sub> monolayer. We also further construct its <i>p-n</i> junction diode and study its spin transport properties by using density functional theory combined with non-equilibrium Green's function method. The results show that the phonon spectrum of the Nb<sub>3</sub>Cl<sub>8</sub> monolayer has no negative frequency, confirming its dynamic stability. The band gap of the spin-down state (1.157 eV) is significantly larger than that of the spin-up state (0.639 eV). The magnetic moment of the Nb<sub>3</sub>Cl<sub>8</sub> monolayer is 0.997 μ<sub>B</sub>, and its easy magnetization axis is in the plane and along the <i>x</i> axis direction based on its energy of magnetic anisotropy. Nb atoms make the main contribution to the magnetic anisotropy. When the strain is applied, the band gap of the spin-down states will decrease, while the band gap of the spin-up state is monotonously decreased from the negative (compress) to positive (tensile) strain. As the strain variable goes from -6% to 6%, the contribution of Nb atoms to the total magnetic moment gradually increases. Moreover, strain causes the easy magnetization axis of the Nb<sub>3</sub>Cl<sub>8</sub> monolayer to flip vertically from in-plane to out-plane. The designed <i>p-n</i> junction diode nanodevice based on Nb<sub>3</sub>Cl<sub>8</sub> monolayer exhibits an obvious rectification effect. In addition, the current in the spin-up state is larger than that in the spin-down state, exhibiting a spin-polarized transport behavior. Moreover, a negative differential resistance (NDR) phenomenon is also observed, which could be used in the NDR devices. These results demonstrate that the Nb<sub>3</sub>Cl<sub>8</sub> monolayer material has great potential application in the next generation of high-performance spintronic devices, and further experimental verification and exploration of this material and related two-dimensional materials are needed.

Magnetic and spin transport properties of a two-dimensional magnetic semiconductor kagome lattice Nb<sub>3</sub>Cl<sub>8</sub> monolayer

Two-dimensional semiconductor materials with intrinsic magnetism have great application prospects in realizing spintronic devices with low power consumption, small size and high efficiency. Some two-dimensional materials with special lattice structures, such as kagome lattice crystals, are favored by researchers because of their novel properties in magnetism and electronic properties. Recently, a new two-dimensional magnetic semiconductor material Nb<sub>3</sub>Cl<sub>8</sub> monolayer with kagome lattice structure was successfully prepared, which provides a new platform for exploring two-dimensional magnetic semiconductor devices with kagome structure. In this work, we study the electronic structure and magnetic anisotropy of Nb<sub>3</sub>Cl<sub>8</sub> monolayer. We also further construct its <em>p-n</em> junction diode and study its spin transport properties by using density functional theory combined with non-equilibrium Green's function method. The results show that the phonon spectrum of the Nb<sub>3</sub>Cl<sub>8</sub> monolayer has no negative frequency, confirming its dynamic stability. The band gap of the spin-down state (1.157 eV) is significantly larger than that of the spin-up state (0.639 eV). The magnetic moment of the Nb<sub>3</sub>Cl<sub>8</sub> monolayer is 0.997 μ<sub>B</sub>, and its easy magnetization axis is in the plane and along the <em>x</em> axis direction based on its energy of magnetic anisotropy. Nb atoms make the main contribution to the magnetic anisotropy. When the strain is applied, the band gap of the spin-down states will decrease, while the band gap of the spin-up state is monotonously decreased from the negative (compress) to positive (tensile) strain. As the strain variable goes from -6% to 6%, the contribution of Nb atoms to the total magnetic moment gradually increases. Moreover, strain causes the easy magnetization axis of the Nb<sub>3</sub>Cl<sub>8</sub> monolayer to flip vertically from in-plane to out-plane. The designed <em>p-n</em> junction diode nanodevice based on Nb<sub>3</sub>Cl<sub>8</sub> monolayer exhibits an obvious rectification effect. In addition, the current in the spin-up state is larger than that in the spin-down state, exhibiting a spin-polarized transport behavior. Moreover, a negative differential resistance (NDR) phenomenon is also observed, which could be used in the NDR devices. These results demonstrate that the Nb<sub>3</sub>Cl<sub>8</sub> monolayer material has great potential application in the next generation of high-performance spintronic devices, and further experimental verification and exploration of this material and related two-dimensional materials are needed.

Tunable Electronic and Magnetic Properties of T-CrTe2 Monolayer by Li Adsorption

Using first-principle calculations, we investigate the electronic and magnetic properties of Li-adsorbed T-CrTe2 monolayer. We demonstrate that Li adsorption turns the electronic properties mainly through electron doping and lattice expansion. As the adsorption concentration increases from 3.7% to 33.3%, the magnetic moment of Cr increases from 2.25 to 2.98μB linearly. More interesting, the T-CrTe2 monolayer becomes ferromagnetic semiconductors with indirect band gaps under the tensile strain. While a tensile strain is applied, a transformation from metal to half-metal has been found. Our work provides an efficient strategy to seek magnetism and produce two-dimensional magnetic semiconductors and half-metals from metals.

Electric-Field-Tunable Spin Polarization and Carrier-Transport Anisotropy in an A-Type Antiferromagnetic van der Waals Bilayer

Two-dimensional (2D) magnetic semiconductor materials with the electric-field-tunable spin polarization and carrier-transport anisotropy are of great significance for the fundamental physics and device application. Here we propose a general strategy to tune the spin polarization and anisotropic effective mass in a 2D A-type antiferromagnetic (AFM) bilayer system. We take the A-type AFM bilayer $\mathrm{CrSBr}$ (with the intralayer ferromagnetic and interlayer AFM coupling) as an example to confirm this design principle. Firstly, a vertical electric field can lift the spin degeneracy in the A-type AFM bilayer $\mathrm{CrSBr}$. By flipping the direction of electric field, the spin polarization direction can be reversed. Secondly, in the A-type AFM bilayer $\mathrm{CrSBr}$ with an interlayer twist angle of 90\ifmmode^\circ\else\textdegree\fi{}, both the spin direction and the carrier-transport anisotropy can be tuned simultaneously by applying a vertical electric field due to the in-plane anisotropic carrier effective mass in each $\mathrm{CrSBr}$ monolayer. This opens an opportunity for controlling the spin polarization as well as carrier-transport anisotropy in the 2D magnetic van der Waals layered materials by interlayer twist and electric field, and provides an idea for utilizing A-type AFM semiconductors to design spintronic devices.

Two-dimensional diamane-like [formula omitted] and [formula omitted]: Wide bandgap and bipolar magnetic semiconductors

Two-dimensional bipolar magnetic semiconductors demonstrate great application potential in developing novelty spintronic devices. Here, we explore the electronic and magnetic characteristics of diamane-like structures Si2C(Ge)2H2 and Si2C(Ge)2H based on the first-principles calculations. The results uncover that Si2C(Ge)2H2 are wide bandgap semiconductors and Si2C(Ge)2H are bipolar magnetic semiconductors. Further calculations demonstrate the flexible magnetic structures for Si2C2H-I, Si2C2H-II, Si2Ge2H-I and Si2Ge2H-II based on the external strain field. Significantly, the magnetic type transforming from bipolar magnetic semiconductor to half semiconductor happens when appropriate strain is applied on the structure with a narrow spin-conserved energy gap. Our work enrich the diversity of 2D magnetic semiconductors and put forward a series of materials for the candidates of spintronic applications.

Janus V2AsP monolayer : a ferromagnetic semiconductor with a narrow band gap, a high Curie temperature and controllable magnetic anisotropy

The search and design of two-dimensional (2D) magnetic semiconductors for spintronics applications are particularly significant. In this work, we investigated the electronic and magnetic properties of Janus structure based on Dirac half-metallic vanadium phosphide (VP) monolayer (ML) by first-principles calculations. Due to the vertical symmetry breaking, Janus V2AsP ML becomes an intrinsic ferromagnetic semiconductor with a narrow band gap of 0.21 eV. We analyzed the electronic structure and origin of the in-plane easy axis in Janus V2AsP. The electron effective mass is anisotropic and only 0.129 m0 along the x-direction. The Curie temperature and magnetic anisotropy energy (MAE) of Janus V2AsP reach 490 K and 178 µeV per V atom, respectively. A uniaxial tensile stain ɛ x of 5% can increase its band gap and MAE to 0.39 eV and 210.6 µeV per V atom while maintaining its being above room temperature. Moreover, the direction of the easy axis can be changed between the in-plane x- and y-direction by a small uniaxial tensile strain ɛ x of 2%. Our study can motivate further research on the design the magnetic semiconductors in Janus structures based on 2D Dirac half-metals for spintronics applications.

Strong Dzyaloshinskii-Moriya interaction in monolayer CrI3 on metal substrates

Dzyaloshinskii-Moriya interaction (DMI) is the primary mechanism for realizing real-space chiral spin textures, which are regarded as key components for the next-generation spintronics. However, DMI arises from a perturbation term of the spin-orbit interaction and is usually weak in pristine magnetic semiconductors. To date, large DMI and the resulting skyrmions are only realized in a few materials under stringent conditions. Using first-principles calculations, we demonstrate that significant DMI occurs between nearest-neighbor Cr atoms in two-dimensional (2D) magnetic semiconductor CrI$_3$ on Au or Cu substrates. This exceptionally strong DMI is generated by the interfacial charge transfer and weak chemical interactions between chromium halides and metal substrates, which break the spatial inversion symmetry. These findings highlight the significance of substrate effects in 2D magnets and expand the inventory of feasible materials with strong DMI.

Exciton-coupled coherent magnons in a 2D semiconductor.

The recent discoveries of two-dimensional (2D) magnets1-6 and their stacking into van der Waals structures7-11 have expanded the horizon of 2D phenomena. One exciting application is to exploit coherent magnons12 as energy-efficient information carriers in spintronics and magnonics13,14 or as interconnects in hybrid quantum systems15-17. A particular opportunity arises when a 2D magnet is also a semiconductor, as reported recently for CrSBr (refs. 18-20) and NiPS3 (refs. 21-23) that feature both tightly bound excitons with a large oscillator strength and potentially long-lived coherent magnons owing to the bandgap and spatial confinement. Although magnons and excitons are energetically mismatched by orders of magnitude, their coupling can lead to efficient optical access to spin information. Here we report strong magnon-exciton coupling in the 2D A-type antiferromagnetic semiconductor CrSBr. Coherent magnons launched by above-gap excitation modulate the exciton energies. Time-resolved exciton sensing reveals magnons that can coherently travel beyond seven micrometres, with a coherence time of above five nanoseconds. We observe these exciton-coupled coherent magnons in both even and odd numbers of layers, with and without compensated magnetization, down to the bilayer limit. Given the versatility of van der Waals heterostructures, these coherent 2D magnons may be a basis for optically accessible spintronics, magnonics and quantum interconnects.

Ultrathin ferrite nanosheets for room-temperature two-dimensional magnetic semiconductors

The discovery of magnetism in ultrathin crystals opens up opportunities to explore new physics and to develop next-generation spintronic devices. Nevertheless, two-dimensional magnetic semiconductors with Curie temperatures higher than room temperature have rarely been reported. Ferrites with strongly correlated d-orbital electrons may be alternative candidates offering two-dimensional high-temperature magnetic ordering. This prospect is, however, hindered by their inherent three-dimensional bonded nature. Here, we develop a confined-van der Waals epitaxial approach to synthesizing air-stable semiconducting cobalt ferrite nanosheets with thickness down to one unit cell using a facile chemical vapor deposition process. The hard magnetic behavior and magnetic domain evolution are demonstrated by means of vibrating sample magnetometry, magnetic force microscopy and magneto-optical Kerr effect measurements, which shows high Curie temperature above 390 K and strong dimensionality effect. The addition of room-temperature magnetic semiconductors to two-dimensional material family provides possibilities for numerous novel applications in computing, sensing and information storage.

First- and second-order magneto-optical effects and intrinsically anomalous transport in the two-dimensional van der Waals layered magnets CrXY (X=S,Se,Te;Y=Cl,Br,I)

Recently, the two-dimensional magnetic semiconductor CrSBr has attracted considerable attention due to its excellent air-stable property and high magnetic critical temperature. Here, we systematically investigate the electronic structure, magnetocrystalline anisotropy energy, first-order magneto-optical effects (Kerr and Faraday effects), and second-order magneto-optical effects (Sch\"afer-Hubert and Voigt effects) as well as intrinsically anomalous transport properties (anomalous Hall, anomalous Nernst, and anomalous thermal Hall effects) of two-dimensional van der Waals layered magnets $\mathrm{Cr}\mathit{XY} (X=\mathrm{S},\mathrm{Se},\mathrm{Te};Y=\mathrm{Cl},\mathrm{Br},\mathrm{I})$ by using first-principles calculations. Our results show that monolayer and bilayer $\mathrm{Cr}\mathit{XY} (X=\mathrm{S},\mathrm{Se})$ are narrow-band-gap semiconductors, whereas monolayer and bilayer $\mathrm{CrTe}Y$ are multiband metals. The magnetic ground states of bilayer $\mathrm{Cr}\mathit{XY}$ and the easy magnetization axis of monolayer and bilayer $\mathrm{Cr}\mathit{XY}$ are confirmed by the magnetocrystalline anisotropy energy calculations. Utilizing magnetic group theory analysis, the first-order magneto-optical effects as well as anomalous Hall, anomalous Nernst, and anomalous thermal Hall effects are identified to exist in a ferromagnetic state with out-of-plane magnetization. The second-order magneto-optical effects are not restricted by the above symmetry requirements, and therefore they can arise in ferromagnetic and antiferromagnetic states with in-plane magnetization. The calculated results are compared with the available theoretical and experimental data of other two-dimensional magnets and some conventional ferromagnets. The present work reveals that monolayer and bilayer $\mathrm{Cr}\mathit{XY}$ with superior magneto-optical responses and anomalous transport properties provide an excellent material platform for the promising applications of magneto-optical devices, spintronics, and spin caloritronics.

Vanadium-Doped Molybdenum Diselenide Atomic Layers with Room-Temperature Ferromagnetism.

Diluted two-dimensional magnetic semiconductors with high Curie temperature are highly sought after because of their potential applications in spintronics. Development of new techniques for preparation of high quality diluted magnetic semiconductors is critical for their applications. In this study, vanadium-doped molybdenum selenide, a new diluted magnetic semiconductor, was synthesized by a single-step chemical vapor deposition method. The merit of this method is that the molybdenum and vanadium precursors can be supplied to the growth substrate uniformly. Photoluminescence measurements reveal that the band gap of MoSe2 decreases after doping, which can be attributed to the formation of impurity energy band caused by p-type doping at the valence band maximum. Thus, the V-doped MoSe2 still maintains the semiconducting characteristics. Vibrating sample magnetometer studies clearly show the ferromagnetism of V-doped MoSe2 at room temperature. DFT calculations illustrates the joint contribution of V dopants and nearby atoms to the magnetic moments. This study provides future prospects for the multifunctional application of two-dimensional materials.

Spin Ordering Induced Broadband Photodetection Based on Two-Dimensional Magnetic Semiconductor α-MnSe.

Two‐dimensional (2D) magnetic semiconductors are considered to have great application prospects in spintronic logic devices, memory devices, and photodetectors, due to their unique structures and outstanding physical properties in 2D confinement. Understanding the influence of magnetism on optical/optoelectronic properties of 2D magnetic semiconductors is a significant issue for constructing multifunctional electronic devices and implementing sophisticated functions. Herein, the influence of spin ordering and magnons on the optical/optoelectronic properties of 2D magnetic semiconductor α‐MnSe synthesized by space‐confined chemical vapor deposition (CVD) is explored systematically. The spin‐ordering‐induced magnetic phase transition triggers temperature‐dependent photoluminescence spectra to produce a huge transition at Néel temperature (T N ≈ 160 K). The magnons‐ and defects‐induced emissions are the primary luminescence path below T N and direct internal 4 aT1g→6A1g transition‐induced emissions are the main luminescence path above T N . Additionally, the magnons and defect structures endow 2D α‐MnSe with a broadband luminescence from 550 to 880 nm, and an ultraviolet–near‐infrared photoresponse from 365 to 808 nm. Moreover, the device also demonstrates improved photodetection performance at 80 K, possibly influenced by spin ordering and trap states associated with defects. These above findings indicate that 2D magnetic semiconductor α‐MnSe provides an excellent platform for magneto‐optical and magneto‐optoelectronic research.