Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userOptical spin pumping induced pseudo-magnetic field in two dimensional heterostructures
138
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Two dimensional heterostructures are likely to provide new avenues for the manipulation of magnetization that is crucial for spintronics or magnetoelectronics. Here, we demonstrate that optical spin pumping can generate a large effective magnetic field in two dimensional MoSe2/WSe2 heterostructures. We determine the strength of the generated field by polarization-resolved measurement of the interlayer exciton photoluminescence spectrum: the measured splitting exceeding 10 milli-electron volts (meV) between the emission originating from the two valleys corresponds to an effective magnetic field of ~ 30 T. The strength of this optically induced field can be controlled by the excitation light polarization. Our finding opens up new possibilities for optically controlled spintronic devices based on van der Waals heterostructures.
rate research
Read More
Tunable magnetic interactions in high-mobility nonmagnetic semiconductor heterostructures are centrally important to spin-based quantum technologies. Conventionally, this requires incorporation of magnetic impurities within the two-dimensional (2D) electron layer of the heterostructures, which is achieved either by doping with ferromagnetic atoms, or by electrostatically printing artificial atoms or quantum dots. Here we report experimental evidence of a third, and intrinsic, source of localized spins in high-mobility GaAs/AlGaAs heterostructures, which are clearly observed in the limit of large setback distance (=80 nm) in modulation doping. Local nonequilibrium transport spectroscopy in these systems reveals existence of multiple spins, which are located in a quasi-regular manner in the 2D Fermi sea, and mutually interact at temperatures below 100 milliKelvin via the Ruderman-Kittel-Kasuya-Yosida (RKKY) indirect exchange. The presence of such a spin-array, whose microscopic origin appears to be disorder-bound, simulates a 2D lattice-Kondo system with gate-tunable energy scales.
We report density dependent instabilities in the localised regime of mesoscopic two-dimensional electron systems (2DES) with intermediate strength of background disorder. They are manifested by strong resistance oscillations induced by high perpendicular magnetic fields B_{perp}. While the amplitude of the oscillations is strongly enhanced with increasing B_{perp}, their position in density remains unaffected. The observation is accompanied by an unusual behaviour of the temperature dependence of resistance and activation energies. We suggest the interplay between a strongly interacting electron phase and the background disorder as a possible explanation.
Van der Waals heterostructures formed by two different monolayer semiconductors have emerged as a promising platform for new optoelectronic and spin/valleytronic applications. In addition to its atomically thin nature, a two-dimensional semiconductor heterostructure is distinct from its three-dimensional counterparts due to the unique coupled spin-valley physics of its constituent monolayers. Here, we report the direct observation that an optically generated spin-valley polarization in one monolayer can be transferred between layers of a two-dimensional MoSe2-WSe2 heterostructure. Using nondegenerate optical circular dichroism spectroscopy, we show that charge transfer between two monolayers conserves spin-valley polarization and is only weakly dependent on the twist angle between layers. Our work points to a new spin-valley pumping scheme in nanoscale devices, provides a fundamental understanding of spin-valley transfer across the two-dimensional interface, and shows the potential use of two-dimensional semiconductors as a spin-valley generator in 2D spin/valleytronic devices for storing and processing information.
High spin to charge conversion efficiency is the requirement for the spintronics devices which is governed by spin pumping and inverse spin Hall effect (ISHE). In last one decade, ISHE and spin pumping are heavily investigated in ferromagnet/ heavy metal (HM) heterostructures. Recently antiferromagnetic (AFM) materials are found to be good replacement of HMs because AFMs exhibit terahertz spin dynamics, high spin-orbit coupling, and absence of stray field. In this context we have performed the ISHE in CoFeB/ IrMn heterostructures. Spin pumping study is carried out for $Co_{40}Fe_{40}B_{20} (12 nm)/ Cu (3 nm)/ Ir_{50}Mn_{50} (t nm)/ AlO_{x} (3 nm)$ samples where textit{t} value varies from 0 to 10 nm. Damping of all the samples are higher than the single layer CoFeB which indicates that spin pumping due to IrMn is the underneath mechanism. Further the spin pumping in the samples are confirmed by angle dependent ISHE measurements. We have also disentangled other spin rectifications effects and found that the spin pumping is dominant in all the samples. From the ISHE analysis the real part of spin mixing conductance (textit{$g_{r}^{uparrow downarrow}$}) is found to be 0.704 $pm$ 0.003 $times$ $10^{18}$ $m^{-2}$.
Introduction of a Josephson field effect transistor (JoFET) concept sparked active research on proximity effects in semiconductors. Induced superconductivity and electrostatic control of critical current has been demonstrated in two-dimensional gases in InAs, graphene and topological insulators, and in one-dimensional systems including quantum spin Hall edges. Recently, interest in superconductor-semiconductor interfaces was renewed by the search for Majorana fermions, which were predicted to reside at the interface. More exotic non-Abelian excitations, such as parafermions (fractional Majorana fermions) or Fibonacci fermions may be formed when fractional quantum Hall edge states interface with superconductivity. In this paper we develop transparent superconducting contacts to high mobility two-dimensional electron gas (2DEG) in GaAs and demonstrate induced superconductivity across several microns. Supercurrent in a ballistic junction has been observed across 0.6 $mu$m of 2DEG, a regime previously achieved only in point contacts but essential to the formation of well separated non-Abelian states. High critical fields ($>16$ Tesla) in NbN contacts enables investigation of a long-sought regime of an interplay between superconductivity and strongly correlated states in a 2DEG at high magnetic fields.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
