Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Raman fingerprint of two terahertz spin wave branches in a two-dimensional honeycomb Ising ferromagnet.

ABSTRACT: Two-dimensional (2D) magnetism has been long sought-after and only very recently realized in atomic crystals of magnetic van der Waals materials. So far, a comprehensive understanding of the magnetic excitations in such 2D magnets remains missing. Here we report polarized micro-Raman spectroscopy studies on a 2D honeycomb ferromagnet CrI₃. We show the definitive evidence of two sets of zero-momentum spin waves at frequencies of 2.28 terahertz (THz) and 3.75?THz, respectively, that are three orders of magnitude higher than those of conventional ferromagnets. By tracking the thickness dependence of both spin waves, we reveal that both are surface spin waves with lifetimes an order of magnitude longer than their temporal periods. Our results of two branches of high-frequency, long-lived surface spin waves in 2D CrI₃ demonstrate intriguing spin dynamics and intricate interplay with fluctuations in the 2D limit, thus opening up opportunities for ultrafast spintronics incorporating 2D magnets.

SUBMITTER: Jin W

PROVIDER: S-EPMC6269484 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Spin density wave instability in a ferromagnet.

Project description:Due to its cooperative nature, magnetic ordering involves a complex interplay between spin, charge, and lattice degrees of freedom, which can lead to strong competition between magnetic states. Binary Fe3Ga4 is one such material that exhibits competing orders having a ferromagnetic (FM) ground state, an antiferromagnetic (AFM) behavior at intermediate temperatures, and a conspicuous re-entrance of the FM state at high temperature. Through a combination of neutron diffraction experiments and simulations, we have discovered that the AFM state is an incommensurate spin-density wave (ISDW) ordering generated by nesting in the spin polarized Fermi surface. These two magnetic states, FM and ISDW, are seldom observed in the same material without application of a polarizing magnetic field. To date, this unusual mechanism has never been observed and its elemental origins could have far reaching implications in many other magnetic systems that contain strong competition between these types of magnetic order. Furthermore, the competition between magnetic states results in a susceptibility to external perturbations allowing the magnetic transitions in Fe3Ga4 to be controlled via temperature, magnetic field, disorder, and pressure. Thus, Fe3Ga4 has potential for application in novel magnetic memory devices, such as the magnetic components of tunneling magnetoresistance spintronics devices.

| S-EPMC5869675 | biostudies-literature

Coherent two-dimensional terahertz-terahertz-Raman spectroscopy.

Project description:We present 2D terahertz-terahertz-Raman (2D TTR) spectroscopy, the first technique, to our knowledge, to interrogate a liquid with multiple pulses of terahertz (THz) light. This hybrid approach isolates nonlinear signatures in isotropic media, and is sensitive to the coupling and anharmonicity of thermally activated THz modes that play a central role in liquid-phase chemistry. Specifically, by varying the timing between two intense THz pulses, we control the orientational alignment of molecules in a liquid, and nonlinearly excite vibrational coherences. A comparison of experimental and simulated 2D TTR spectra of bromoform (CHBr3), carbon tetrachloride (CCl4), and dibromodichloromethane (CBr2Cl2) shows previously unobserved off-diagonal anharmonic coupling between thermally populated vibrational modes.

| S-EPMC4922159 | biostudies-literature

Two-dimensional Raman-terahertz spectroscopy of water.

Project description:Two-dimensional Raman-terahertz (THz) spectroscopy is presented as a multidimensional spectroscopy directly in the far-IR regime. The method is used to explore the dynamics of the collective intermolecular modes of liquid water at ambient temperatures that emerge from the hydrogen-bond networks water forming. Two-dimensional Raman-THz spectroscopy interrogates these modes twice and as such can elucidate couplings and inhomogeneities of the various degrees of freedoms. An echo in the 2D Raman-THz response is indeed identified, indicating that a heterogeneous distribution of hydrogen-bond networks exists, albeit only on a very short 100-fs timescale. This timescale appears to be too short to be compatible with more extended, persistent structures assumed within a two-state model of water.

| S-EPMC3870715 | biostudies-literature

High spin-wave propagation length consistent with low damping in a metallic ferromagnet.

Project description:We report ultralow intrinsic magnetic damping in Co25Fe75 heterostructures, reaching the low 10-4 regime at room temperature. By using a broadband ferromagnetic resonance technique in out-of-plane geometry, we extracted the dynamic magnetic properties of several Co25Fe75-based heterostructures with varying ferromagnetic layer thicknesses. By measuring radiative damping and spin pumping effects, we found the intrinsic damping of a 26 nm thick sample to be α0 ≲ 3.18 × 10-4. Furthermore, using Brillouin light scattering microscopy, we measured spin-wave propagation lengths of up to (21 ± 1) μm in a 26 nm thick Co25Fe75 heterostructure at room temperature, which is in excellent agreement with the measured damping.

| S-EPMC7607910 | biostudies-literature

Spin pumping in ferromagnet-topological insulator-ferromagnet heterostructures.

Project description:Topological insulators (TIs) are enticing prospects for the future of spintronics due to their large spin-orbit coupling and dissipationless, counter-propagating conduction channels in the surface state. However, a means to interact with and exploit the topological surface state remains elusive. Here, we report a study of spin pumping at the TI-ferromagnet interface, investigating spin transfer dynamics in a spin-valve like structure using element specific time-resolved x-ray magnetic circular dichroism, and ferromagnetic resonance. Gilbert damping increases approximately linearly with increasing TI thickness, indicating efficient behaviour as a spin sink. However, layer-resolved measurements suggest that a dynamic coupling is limited. These results shed new light on the spin dynamics of this novel material class, and suggest great potential for TIs in spintronic devices, through their novel magnetodynamics that persist even up to room temperature.

| S-EPMC4298741 | biostudies-literature

100,000-spin coherent Ising machine.

Project description:Computers based on physical systems are increasingly anticipated to overcome the impending limitations on digital computer performance. One such computer is a coherent Ising machine (CIM) for solving combinatorial optimization problems. Here, we report a CIM with 100,512 degenerate optical parametric oscillator pulses working as the Ising spins. We show that the CIM delivers fine solutions to maximum cut problems of 100,000-node graphs drastically faster than standard simulated annealing. Moreover, the CIM, when operated near the phase transition point, provides some extremely good solutions and a very broad distribution. This characteristic will be useful for applications that require fast random sampling such as machine learning.

| S-EPMC8480917 | biostudies-literature

Spin flip statistics and spin wave interference patterns in Ising ferromagnetic films: A Monte Carlo study.

Project description:The spin wave interference is studied in two dimensional Ising ferromagnet driven by two coherent spherical magnetic field waves by Monte Carlo simulation. The spin waves are found to propagate and interfere according to the classic rule of interference pattern generated by two point sources. The interference pattern of spin wave is observed in one boundary of the lattice. The interference pattern is detected and studied by spin flip statistics at high and low temperatures. The destructive interference is manifested as the large number of spin flips and vice versa.

| S-EPMC5541143 | biostudies-other

Terahertz Fingerprint of Monolayer Wigner Crystals.

Project description:The strong Coulomb interaction in monolayer semiconductors represents a unique opportunity for the realization of Wigner crystals without external magnetic fields. In this work, we predict that the formation of monolayer Wigner crystals can be detected by their terahertz response spectrum, which exhibits a characteristic sequence of internal optical transitions. We apply the density matrix formalism to derive the internal quantum structure and the optical conductivity of the Wigner crystal and to microscopically analyze the multipeak shape of the obtained terahertz spectrum. Moreover, we predict a characteristic shift of the peak position as a function of charge density for different atomically thin materials and show how our results can be generalized to an arbitrary two-dimensional system.

| S-EPMC8832488 | biostudies-literature

Two-Dimensional Pnictogen Honeycomb Lattice: Structure, On-Site Spin-Orbit Coupling and Spin Polarization.

Project description:Because of its novel physical properties, two-dimensional materials have attracted great attention. From first-principle calculations and vibration frequencies analysis, we predict a new family of two-dimensional materials based on the idea of octet stability: honeycomb lattices of pnictogens (N, P, As, Sb, Bi). The buckled structures of materials come from the sp(3) hybridization. These materials have indirect band gap ranging from 0.43 eV to 3.7 eV. From the analysis of projected density of states, we argue that the s and p orbitals together are sufficient to describe the electronic structure under tight-binding model, and the tight-binding parameters are obtained by fitting the band structures to first-principle results. Surprisingly large on-site spin-orbit coupling is found for all the pnictogen lattices except nitrogen. Investigation on the electronic structures of both zigzag and armchair nanoribbons reveals the possible existence of spin-polarized ferromagnetic edge states in some cases, which are rare in one-dimensional systems. These edge states and magnetism may exist under the condition of high vacuum and low temperature. This new family of materials would have promising applications in electronics, optics, sensors, and solar cells.

| S-EPMC4485072 | biostudies-other

Antiferromagnetic spin ordering in two-dimensional honeycomb lattice of SiP<sub>3</sub>.

Project description:Magnetism in low-dimensional materials has been of sustained interest due to its intriguing quantum mechanical origin and promising device applications. Here, we propose a buckled honeycomb lattice of stoichiometry SiP3, a two-dimensional binary group-IV and V material that exhibits an antiferromagnetic ground state with itinerant electrons. Here we perform elemental Si substitution in pristine blue phosphorene to downshift the Fermi energy and induce the Fermi instability that results in a spin polarized ground state. Within first-principles calculations, we observe antiferromagnetic spin alignment between adjacent ferromagnetic triangular domains where each Si atom is coupled with three neighboring P atoms with a ferromagnetic interaction. Such unique spin structure and resulting magnetic ground state are unprecedented in defect-free two-dimensional materials made of only p-block elements. This metal-free magnetism can be exploited for advanced spintronic and memory storage applications.

| S-EPMC9417914 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data