Browse
Submit Data
Databases
API
Help

Dataset Information

36 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Highly-Tunable Intrinsic Room-Temperature Ferromagnetism in 2D van der Waals Semiconductor Cr_x Ga_1- _x Te.

ABSTRACT: The combination of semiconductivity and tunable ferromagnetism is pivotal for electrical control of ferromagnetism and next-generation low-power spintronic devices. However, Curie temperatures (T_C ) for most traditional intrinsic ferromagnetic semiconductors (≤200 K) and recently discovered two-dimensional (2D) ones (<70 K) are far below room temperature. 2D van der Waals (vdW) semiconductors with intrinsic room-temperature ferromagnetism remain elusive considering the unfavored 2D long-range ferromagnetic order indicated by Mermin-Wagner theorem. Here, vdW semiconductor Cr_x Ga_1- _x Te crystals exhibiting highly tunable above-room-temperature ferromagnetism with bandgap 1.62-1.66 eV are reported. The saturation magnetic moment (M_sat ) of Cr_x Ga_1- _x Te crystals can be effectively regulated up to ≈5.4 times by tuning Cr content and ≈75.9 times by changing the thickness. vdW Cr_x Ga_1- _x Te ultrathin semiconductor crystals show robust room-temperature ferromagnetism with the 2D quantum confinement effect, enabling T_C 314.9-329 K for nanosheets, record-high for intrinsic vdW 2D ferromagnetic semiconductors. This work opens an avenue to room-temperature 2D vdW ferromagnetic semiconductor for 2D electronic and spintronic devices.

SUBMITTER: Zhang G

PROVIDER: S-EPMC8728846 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Nearly room temperature ferromagnetism in a magnetic metal-rich van der Waals metal.

Project description:In spintronics, two-dimensional van der Waals crystals constitute a most promising material class for long-distance spin transport or effective spin manipulation at room temperature. To realize all-vdW-material-based spintronic devices, however, vdW materials with itinerant ferromagnetism at room temperature are needed for spin current generation and thereby serve as an effective spin source. We report theoretical design and experimental realization of a iron-based vdW material, Fe4GeTe2, showing a nearly room temperature ferromagnetic order, together with a large magnetization and high conductivity. These properties are well retained even in cleaved crystals down to seven layers, with notable improvement in perpendicular magnetic anisotropy. Our findings highlight Fe4GeTe2 and its nanometer-thick crystals as a promising candidate for spin source operation at nearly room temperature and hold promise to further increase T c in vdW ferromagnets by theory-guided material discovery.

| S-EPMC6968938 | biostudies-literature

Tunable room-temperature ferromagnetism in Co-doped two-dimensional van der Waals ZnO.

Project description:The recent discovery of ferromagnetism in two-dimensional van der Waals crystals has provoked a surge of interest in the exploration of fundamental spin interaction in reduced dimensions. However, existing material candidates have several limitations, notably lacking intrinsic room-temperature ferromagnetic order and air stability. Here, motivated by the anomalously high Curie temperature observed in bulk diluted magnetic oxides, we demonstrate room-temperature ferromagnetism in Co-doped graphene-like Zinc Oxide, a chemically stable layered material in air, down to single atom thickness. Through the magneto-optic Kerr effect, superconducting quantum interference device and X-ray magnetic circular dichroism measurements, we observe clear evidences of spontaneous magnetization in such exotic material systems at room temperature and above. Transmission electron microscopy and atomic force microscopy results explicitly exclude the existence of metallic Co or cobalt oxides clusters. X-ray characterizations reveal that the substitutional Co atoms form Co2+ states in the graphitic lattice of ZnO. By varying the Co doping level, we observe transitions between paramagnetic, ferromagnetic and less ordered phases due to the interplay between impurity-band-exchange and super-exchange interactions. Our discovery opens another path to 2D ferromagnetism at room temperature with the advantage of exceptional tunability and robustness.

| S-EPMC8233323 | biostudies-literature

Van der Waals lattice-induced colossal magnetoresistance in Cr2Ge2Te6 thin flakes.

Project description:Recent discovery of two-dimensional (2D) magnets with van der Waals (vdW) gapped layered structure prospers the fundamental research of magnetism and advances the miniaturization of spintronics. Due to their unique lattice anisotropy, their band structure has the potential to be dramatically modulated by the spin configuration even in thin flakes, which is still unexplored. Here, we demonstrate the vdW lattice-induced spin modulation of band structure in thin flakes of vdW semiconductor Cr2Ge2Te6 (CGT) through the measurement of magnetoresistance (MR). The significant anisotropic lattice constructed by the interlayer vdW force and intralayer covalent bond induces anisotropic spin-orbit field, resulting in the spin orientation-dependent band splitting. Consequently, giant variation of resistance is induced between the magnetization aligned along in-plane and out-of-plane directions. Based on this, a colossal MR beyond 1000% was realized in lateral nonlocal devices with CGT acting as a magneto switch. Our finding provides a unique feature for the vdW magnets and would advance its applications in spintronics.

| S-EPMC9616818 | biostudies-literature

Magnetic critical behavior of the van der Waals Fe5GeTe2 crystal with near room temperature ferromagnetism.

Project description:The van der Waals ferromagnet Fe5GeTe2 has a Curie temperature TC of about 270 K, which is tunable through controlling the Fe deficiency content and can even reach above room temperature. To achieve insights into its ferromagnetic exchange that gives the high TC, the critical behavior has been investigated by measuring the magnetization in Fe5GeTe2 crystal around the ferromagnetic ordering temperature. The analysis of the measured magnetization by using various techniques harmonically reached to a set of reliable critical exponents with TC = 273.7 K, β = 0.3457 ± 0.001, γ = 1.40617 ± 0.003, and δ = 5.021 ± 0.001. By comparing these critical exponents with those predicted by various models, it seems that the magnetic properties of Fe5GeTe2 could be interpreted by a three-dimensional magnetic exchange with the exchange distance decaying as J(r) ≈ r-4.916, close to that of a three-dimensional Heisenberg model with long-range magnetic coupling.

| S-EPMC7501290 | biostudies-literature

Interfacial engineering of ferromagnetism in wafer-scale van der Waals Fe4GeTe2 far above room temperature.

Project description:Despite recent advances in exfoliated vdW ferromagnets, the widespread application of 2D magnetism requires a Curie temperature (Tc) above room temperature as well as a stable and controllable magnetic anisotropy. Here we demonstrate a large-scale iron-based vdW material Fe4GeTe2 with the Tc reaching ~530 K. We confirmed the high-temperature ferromagnetism by multiple characterizations. Theoretical calculations suggested that the interface-induced right shift of the localized states for unpaired Fe d electrons is the reason for the enhanced Tc, which was confirmed by ultraviolet photoelectron spectroscopy. Moreover, by precisely tailoring Fe concentration we achieved arbitrary control of magnetic anisotropy between out-of-plane and in-plane without inducing any phase disorders. Our finding sheds light on the high potential of Fe4GeTe2 in spintronics, which may open opportunities for room-temperature application of all-vdW spintronic devices.

| S-EPMC10148834 | biostudies-literature

Above-room-temperature strong intrinsic ferromagnetism in 2D van der Waals Fe3GaTe2 with large perpendicular magnetic anisotropy.

Project description:The absence of two-dimensional (2D) van der Waals (vdW) ferromagnetic crystals with both above-room-temperature strong intrinsic ferromagnetism and large perpendicular magnetic anisotropy (PMA) severely hinders practical applications of 2D vdW crystals in next-generation low-power magnetoelectronic and spintronic devices. Here, we report a vdW intrinsic ferromagnetic crystal Fe3GaTe2 that exhibits record-high above-room-temperature Curie temperature (Tc, ~350-380 K) for known 2D vdW intrinsic ferromagnets, high saturation magnetic moment (40.11 emu/g), large PMA energy density (~4.79 × 105 J/m3), and large anomalous Hall angle (3%) at room temperature. Such large room-temperature PMA is better than conventional widely-used ferromagnetic films like CoFeB, and one order of magnitude larger than known 2D vdW intrinsic ferromagnets. Room-temperature thickness and angle-dependent anomalous Hall devices and direct magnetic domains imaging based on Fe3GaTe2 nanosheet have been realized. This work provides an avenue for room-temperature 2D ferromagnetism, electrical control of 2D ferromagnetism and promote the practical applications of 2D-vdW-integrated spintronic devices.

| S-EPMC9424191 | biostudies-literature

Ultrashort Vertical-Channel van der Waals Semiconductor Transistors.

Project description:Atomically thin 2D van der Waals semiconductors are promising candidates for next-generation nanoscale field-effect transistors (FETs). Although large-area 2D van der Waals materials have been successfully synthesized, such nanometer-length-scale devices have not been well demonstrated in 2D van der Waals semiconductors. Here, controllable nanometer-scale transistors with a channel length of ?10 nm are fabricated via vertical channels by squeezing an ultrathin insulating spacer between the out-of-plane source and drain electrodes, and the feasibility of high-density and large-scale fabrication is demonstrated. A large on-current density of ?70 µA µm-1 nm-1 at a source-drain voltage of 0.5 V and a high on/off ratio of ?107-109 are obtained in ultrashort 2D vertical channel FETs with monolayer MoS2 synthesized through chemical vapor deposition. The work provides a promising route toward the complementary metal-oxide-semiconductor-compatible fabrication of wafer-scale 2D van der Waals transistors with high-density integration.

| S-EPMC7029639 | biostudies-literature

Interlayer excitons in a bulk van der Waals semiconductor.

Project description:Bound electron-hole pairs called excitons govern the electronic and optical response of many organic and inorganic semiconductors. Excitons with spatially displaced wave functions of electrons and holes (interlayer excitons) are important for Bose-Einstein condensation, superfluidity, dissipationless current flow, and the light-induced exciton spin Hall effect. Here we report on the discovery of interlayer excitons in a bulk van der Waals semiconductor. They form due to strong localization and spin-valley coupling of charge carriers. By combining high-field magneto-reflectance experiments and ab initio calculations for 2H-MoTe2, we explain their salient features: the positive sign of the g-factor and the large diamagnetic shift. Our investigations solve the long-standing puzzle of positive g-factors in transition metal dichalcogenides, and pave the way for studying collective phenomena in these materials at elevated temperatures.Excitons, quasi-particles of bound electron-hole pairs, are at the core of the optoelectronic properties of layered transition metal dichalcogenides. Here, the authors unveil the presence of interlayer excitons in bulk van der Waals semiconductors, arising from strong localization and spin-valley coupling of charge carriers.

| S-EPMC5608874 | biostudies-other

Room Temperature Uniaxial Magnetic Anisotropy Induced By Fe-Islands in the InSe Semiconductor Van Der Waals Crystal.

Project description:The controlled manipulation of the spin and charge of electrons in a semiconductor has the potential to create new routes to digital electronics beyond Moore's law, spintronics, and quantum detection and imaging for sensing applications. These technologies require a shift from traditional semiconducting and magnetic nanostructured materials. Here, a new material system is reported, which comprises the InSe semiconductor van der Waals crystal that embeds ferromagnetic Fe-islands. In contrast to many traditional semiconductors, the electronic properties of InSe are largely preserved after the incorporation of Fe. Also, this system exhibits ferromagnetic resonances and a large uniaxial magnetic anisotropy at room temperature, offering opportunities for the development of functional devices that integrate magnetic and semiconducting properties within the same material system.

| S-EPMC6051381 | biostudies-literature

Hybrid exciton-plasmon-polaritons in van der Waals semiconductor gratings.

Project description:Van der Waals materials and heterostructures that manifest strongly bound exciton states at room temperature also exhibit emergent physical phenomena and are of great promise for optoelectronic applications. Here, we demonstrate that nanostructured, multilayer transition metal dichalcogenides (TMDCs) by themselves provide an ideal platform for excitation and control of excitonic modes, paving the way to exciton-photonics. Hence, we show that by patterning the TMDCs into nanoresonators, strong dispersion and avoided crossing of exciton, cavity photons and plasmon polaritons with effective separation energy exceeding 410?meV can be controlled with great precision. We further observe that inherently strong TMDC exciton absorption resonances may be completely suppressed due to excitation of hybrid light-matter states and their interference. Our work paves the way to the next generation of integrated exciton optoelectronic nano-devices and applications in light generation, computing, and sensing.

| S-EPMC7363824 | biostudies-literature