5 Search Results

The capability of magnons to hybridize and strongly couple with diverse excitations offers a promising avenue for realizing and controlling emergent properties that hold significant potential for applications in devices, circuits, and information processing. In this Letter, we present recent theoretical and experimental developments in magnon-based hybrid systems, focusing on the combination of magnon excitation in an antiferromagnet with other excitations, namely, plasmons in a topological insulator, phonons in a 2D antiferromagnetic (2D AFM), and photons. Here, the existence of THz frequency magnons, plasmons, and phonons makes magnon-based hybrid systems particularly appealing for high-operating-speed devices. In this context, we exploremore » several directions to advance magnon hybrid systems, including strong coupling between a surface plasmon and magnon polariton in a topological insulator /AFM bilayer, a giant spin Nernst effect induced by magnon–phonon coupling in 2D AFMs, and control of magnon–photon coupling using spin torque.« less

The discovery of topological insulators (TIs) and their unique electronic properties has motivated research into a variety of applications, including quantum computing. It has been proposed that TI surface states will be energetically discretized in a quantum dot nanoparticle. These discretized states could then be used as basis states for a qubit that is more resistant to decoherence. In this work, prototypical TI Bi2Se3 nanoparticles are grown on GaAs (001) using the droplet epitaxy technique, and we demonstrate the control of nanoparticle height, area, and density by changing the duration of bismuth deposition and substrate temperature. Within the growth windowmore » studied, nanoparticles ranged from 5 to 15 nm in height with an 8–18 nm equivalent circular radius, and the density could be relatively well controlled by changing the substrate temperature and bismuth deposition time.« less

The thermal stability of ErAs nanoparticles and bulk-like powders, synthesized by pulsed laser ablation and direct reaction, respectively, is investigated up to 700 °C in N₂. Thermogravimetric analysis and XRD are used to monitor the decomposition temperatures and crystalline compositions of the synthesized powders, respectively. Degradation of unagglomerated nanoparticle powders is observed at 350°C accompanied by the crystallization of amorphous Er₂O₃. Mass balance analysis suggests that the mass loss occurs as a result of arsenic volatilization rather than congruent sublimation of ErAs. Conversely, micron-sized agglomerated particles grown by direct reaction show little evidence for degradation under similar thermal processing conditions.more » This significant decrease in ErAs stability compared to agglomerated powders suggests a size dependence on the degradation characteristics of ErAs.« less

Abstract Lanthanide monopnictide (Ln‐V) nanoparticles embedded within III–V semiconductors, specifically in In _0.53 Ga _0.47 As, are interesting for thermoelectric applications. The electrical conductivity, Seebeck coefficient, and power factor of co‐deposited TbAs:InGaAs over the temperature range of 300–700 K are reported. Using Boltzmann transport theory, it is shown that TbAs nanoparticles in InGaAs matrix give rise to an improved Seebeck coefficient due to an increase in scattering, such as ionized impurity scattering. TbAs nanoparticles act as electron donors in the InGaAs matrix while having minimal effects on electron mobility, and maintain high electrical conductivity. There is further evidence that TbAsmore » nanoparticles act as energy dependent electron scattering sites, contributing to an increased Seebeck coefficient at high temperature. These results show that TbAs:InGaAs nanocomposite thinfilms containing low concentrations, specifically 0.78% TbAs:InGaAs, display high electrical conductivity, reduced thermal conductivity, improved Seebeck coefficient, and demonstrated ZT of power factors as high as 7.1 × 10 ⁻³ W K ⁻² m ⁻¹ and ZT as high as 1.6 at 650 K.« less

We report on the molecular beam epitaxy growth and characterization of TbAs films. In situ reflection high energy electron diffraction and ex situ high resolution X-ray diffraction, reciprocal space mapping, and both scanning and transmission electron microscopy are used to confirm the complete film growth and study the films’ morphology. Spectrophotometry measurements provide the energy of optical transitions, revealing a red shift in optical band gap with increasing thickness. The Hall effect measurements show temperature insensitive carrier concentrations, resistivities, and mobilities. The carrier concentration decreases and resistivity increases with increasing film thickness; mobility appears thickness independent. Here, the films’ reflectivity,more » obtained via Fourier transform infrared spectroscopy, shows a possible Drude edge that differs from the trend of other lanthanide monopnictides. Lastly, these measurements show that TbAs is a degenerately doped semiconductor with a combination of electronic and optical properties that is dissimilar to other lanthanide monopnictides.« less