scholarly journals Observation of strong excitonic magneto-chiral anisotropy in twisted bilayer van der Waals crystals

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shoufeng Lan ◽  
Xiaoze Liu ◽  
Siqi Wang ◽  
Hanyu Zhu ◽  
Yawen Liu ◽  
...  
Keyword(s):  
Time Reversal ◽  
Room Temperature ◽  
Photochemical Reactions ◽  
Full Width ◽  
Half Maximum ◽  
A Value ◽  
Device Applications ◽  
Spectral Splitting ◽  
Iron Garnet ◽  
Spontaneous Magnetic Moment

AbstractThe interplay between chirality and magnetism generates a distinct physical process, the magneto-chiral effect, which enables one to develop functionalities that cannot be achieved solely by any of the two. Such a process is universal with the breaking of parity-inversion and time-reversal symmetry simultaneously. However, the magneto-chiral effect observed so far is weak when the matter responds to photons, electrons, or phonons. Here we report the first observation of strong magneto-chiral response to excitons in a twisted bilayer tungsten disulfide with the amplitude of excitonic magneto-chiral (ExMCh) anisotropy reaches a value of ~4%. We further found the ExMCh anisotropy features with a spectral splitting of ~7 nm, precisely the full-width at half maximum of the excitonic chirality spectrum. Without an externally applied strong magnetic field, the observed ExMCh effect with a spontaneous magnetic moment from the ferromagnetic substrate of thulium iron garnet at room temperature is favorable for device applications. The unique ExMCh processes provide a new pathway to actively control magneto-chiral applications in photochemical reactions, asymmetric synthesis, and drug delivery.

scholarly journals Observation of strong excitonic magneto-chiral anisotropy in twisted bilayer van der Waals crystals

2020 ◽  
Author(s):  
Shoufeng Lan ◽  
Xiaoze Liu ◽  
Siqi Wang ◽  
Hanyu Zhu ◽  
Yawen Liu ◽  
...  
Keyword(s):  
Time Reversal ◽  
Room Temperature ◽  
Photochemical Reactions ◽  
Full Width ◽  
Half Maximum ◽  
A Value ◽  
Device Applications ◽  
Spectral Splitting ◽  
Iron Garnet ◽  
Spontaneous Magnetic Moment

Abstract The interplay between chirality and magnetism generates a distinct physical process, the magneto-chiral effect, which enables one to develop functionalities that cannot be achieved solely by any of the two. Such a process is universal with the breaking of parity-inversion and time-reversal symmetry simultaneously. However, the magneto-chiral effect observed so far is weak when the matter responds to photons, electrons, or phonons. Here we report the first observation of strong magneto-chiral response to excitons in a twisted bilayer tungsten disulfide with the amplitude of excitonic magneto-chiral (ExMCh) anisotropy reaches a value of ~4%. We further found the ExMCh anisotropy features with a spectral splitting of ~7 nm, precisely the full-width at half maximum of the excitonic chirality spectrum. Without an externally applied strong magnetic field, the observed ExMCh effect with a spontaneous magnetic moment from the ferromagnetic substrate of thulium iron garnet at room temperature is favorable for device applications. The unique ExMCh processes provide a new pathway to actively control magneto-chiral applications in photochemical reactions, asymmetric synthesis, and drug delivery.

Photoluminescence of Erbium-Diffused Silicon

1996 ◽  
Vol 422 ◽  
Author(s):  
H. Horiguchi ◽  
T. Kinone ◽  
R. Saito ◽  
T. Kimura ◽  
T. Ikoma
Keyword(s):  
Room Temperature ◽  
Crystalline Silicon ◽  
Luminescence Spectra ◽  
Main Peak ◽  
Silicon Substrates ◽  
Annealing Atmosphere ◽  
Full Width ◽  
Half Maximum ◽  
Strong Luminescence ◽  
Fine Structures

AbstractErbium films are evaporated on crystalline silicon substrates and are thermally diffused into silicon in an Ar+02 or H2 flow. Very sharp Er3+-related luminescence peaks are observed around 1.54 μ m.The main peak as well as the fine structures of the luminescence spectra depend on the annealing atmosphere, suggesting different luminescence centers. The full width at half maximum (FWHM) of the main peaks is ≤ 0.5nm at 20K. Thermal diffusion with Al films on top of the Er films is found to increase the intensity of the Er3+-related peaks greatly. The temperature dependence between 20 K and room temperature is relatively small, and a strong luminescence is obtained at room temperature.

Temperature Dependence of the Band-Edge Injection Electroluminescence of 3C-SiC pn Structure

2007 ◽  
Vol 556-557 ◽  
pp. 427-430 ◽  
Author(s):  
Anatoly M. Strel'chuk ◽  
Alexander A. Lebedev ◽  
N.S. Savkina ◽  
Alexey N. Kuznetsov
Keyword(s):  
Activation Energy ◽  
Emission Band ◽  
Room Temperature ◽  
Free Exciton ◽  
Charge Carriers ◽  
Full Width ◽  
Half Maximum ◽  
Exciton Annihilation ◽  
Increasing Temperature ◽  
Injection Electroluminescence

We present the injection electroluminescence spectra in the temperature range 290-760 K of 3C-SiC pn structure, which was fabricated by sublimation epitaxy in vacuum on 6H-SiC substrate. The dominant emission band of injection electroluminescence (IEL) spectrum was observed in the green region; at room temperature the IEL intensity outside the region of hν ≈ 2.0- 2.5 eV was less than 3% of that of the green peak. The peak parameters at room temperature are: hνmax ≈ 2.32 eV, full width at half maximum w ≈ 100 meV. The green peak shifted in the longwave direction with increasing temperature; the hνmax (T) dependence was linear with the slope of - 1.3x10-4 eV/K. Both the IEL intensity of the green peak at hνmax and band width w increased upon heating. The w(T) dependence was linear with the slope of 4.6x10-4 eV/K; intensity increased with the activation energy of 70 meV. The green IEL band can be considered to be due to the free exciton annihilation or to the band-band recombination and edge IEL increasing with rising temperature can be explained by the nonequilibrium charge carriers lifetime increasing.

Heat Transfer in Encased Graphene

2009 ◽  
Author(s):  
Zhen Chen ◽  
Wanyoung Jang ◽  
Wenzhong Bao ◽  
Chun Ning Lau ◽  
Chris Dames
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Room Temperature ◽  
Heat Dissipation ◽  
Thermal Contact ◽  
Graphene Sheets ◽  
A Value ◽  
Order Of Magnitude ◽  
Device Applications ◽  
Freely Suspended

Experimentally understanding the heat transfer in graphene (sheets of graphite a few atoms thick) is important for fundamental physics as well as device applications. In particular, measurements of the heat flow through graphene encased by oxide layers are essential for future graphene-based nanoelectronics, interconnects, and thermal management structures. Here we use a “heat spreader method” to study the heat dissipation performance of encased graphene. Measurements show enhanced heat spreading by a graphene layer as compared to control samples without graphene. At room temperature, the in-plane thermal conductivity of encased graphene sheets of thickness 2 nm and 5 nm is measured to be ∼150 W/m-K, more than one order of magnitude smaller than a published report for a freely-suspended graphene sheet [A. A. Balandin et al., Nano Lett. 8, 902], as well as bulk graphite. We also used a differential 3ω method to measure the thermal contact resistance between graphene and SiO2, finding a value around 10−8 m2-K/W at room temperature. Possible reasons for the unexpectedly low thermal conductivity are also discussed.

CBE Growth of InP with Triethylindium and Metalorganic Phosphorous Precursors: Bisphosphinoethane and Tertiarybutyl-Phosphine

1992 ◽  
Vol 282 ◽  
Author(s):  
Albert Chin ◽  
Steve Hersee ◽  
Paul Martin ◽  
John Mazurowski ◽  
James Ballingall ◽  
...  
Keyword(s):  
Indium Phosphide ◽  
Room Temperature ◽  
Epitaxial Layers ◽  
Full Width ◽  
Half Maximum ◽  
Substrate Interface ◽  
Sims Analysis

ABSTRACTTwo metallorganic phosphorous precursors, bisphosphinoethane (BPE) and tertiarybutyl phosphine (TBP), were studied. For indium phosphide (InP) grown using BPE, the measured room temperature and 77K Hall mobilities were 4,200 and 22,000 cm2/Vs, with carrierdensities 5.7E15 and 4.0E15 cm−3, respectively. For InP grown using TBP, the measured room temperature and 77K Hall mobilities were 4,400 and 26,000 cm2/Vs, with carrier densities 6.4E15 and 5.1E15 cm−3, respectively. An impurity build-up at the substrate interface is responsible for the relatively low mobility in the adjacent epitaxial layers. SIMS analysis showed that S and Si are the primary impurities measured in films grown with BPE and TBP, respectively; impurity concentrations increasedwith cracking temperature. The full width at half maximum (FWHM) of donor bound exciton peaks measured by 2.2K photoluminescence for InP grown by BPE and TBP were 0.84 and 1.28 meV, respectively.

Research of Angled 8° Integrated 808 nm Wavelength SLDs

2011 ◽  
Vol 84-85 ◽  
pp. 598-602
Author(s):  
Si Yu Zhang ◽  
Zhong Liang Qiao ◽  
Bao Xue Bo ◽  
Xin Gao ◽  
Yi Qu ◽  
...  
Keyword(s):  
Emission Spectrum ◽  
Output Power ◽  
Room Temperature ◽  
Continuous Wave ◽  
Seed Source ◽  
Full Width ◽  
Half Maximum

Integrated 808 nm wavelength super-luminescent diodes (SLDs) with a ring seed source and a tapered amplifier were fabricated tilted at 8° from the facet normal. Max-output power of 700 mW was obtained in continuous wave (CW) mode under room temperature, and the full width at half maximum (FWHM) of the emission spectrum is 36 nm.

Infrared luminescence properties of bismuth-doped barium silicate glasses

2007 ◽  
Vol 22 (7) ◽  
pp. 1954-1958 ◽  
Author(s):  
Jinjun Ren ◽  
Jianrong Qiu ◽  
Danping Chen ◽  
Chen Wang ◽  
Xiongwei Jiang ◽  
...  
Keyword(s):  
Fluorescence Intensity ◽  
Room Temperature ◽  
Full Width Half Maximum ◽  
Wavelength Region ◽  
Silicate Glasses ◽  
Full Width ◽  
Half Maximum ◽  
Infrared Luminescence ◽  
Barium Silicate ◽  
Luminescent Centers

Infrared (IR) luminescence covering 1.1 to ∼1.6 μm wavelength region was observed from bismuth-doped barium silicate glasses, excited by a laser diode at 808 nm wavelength region, at room temperature. The peak of the IR luminescence appears at 1325 nm. A full width half-maximum (FWHM) and the lifetime of the fluorescence is more than 200 nm and 400 μs, respectively. The fluorescence intensity increases with Al2O3 content, but decreases with BaO content. We suggest that the IR luminescence should be ascribed to the low valence state of bismuth Bi2+ or Bi+, and Al3+ ions play an indirect dispersing role for the infrared luminescent centers.

High Performance 785 nm Wavelength Super-Luminescent Diodes

2011 ◽  
Vol 84-85 ◽  
pp. 594-597
Author(s):  
Si Yu Zhang ◽  
Zhong Liang Qiao ◽  
Xin Gao ◽  
Yi Qu ◽  
Guo Jun Liu ◽  
...  
Keyword(s):  
Emission Spectrum ◽  
Output Power ◽  
High Performance ◽  
Room Temperature ◽  
Continuous Wave ◽  
Ring Cavity ◽  
Maximum Output Power ◽  
Maximum Output ◽  
Full Width ◽  
Half Maximum

High-performance 785 nm wavelength super-luminescent diodes (SLDs) with ring cavity were fabricated. The maximum output power of 100 mW was obtained in continuous wave (CW) mode under room temperature. The full width at half maximum (FWHM) of the emission spectrum was 24 nm.

Formation of Nanocluster Colloids of Tin, Gold and Copper in Magnesium Oxide by MeV Ion Implantation

1997 ◽  
Vol 504 ◽  
Author(s):  
R. L. Zimmerman ◽  
D. Ila ◽  
E. K. Williams ◽  
S. Sarkisov ◽  
D. B. Poker ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Single Crystals ◽  
Magnesium Oxide ◽  
Room Temperature ◽  
Full Width Half Maximum ◽  
Rutherford Backscattering Spectrometry ◽  
Threshold Fluence ◽  
Full Width ◽  
Half Maximum ◽  
Absorption Bands

ABSTRACTWe have implanted ions of Sn, Au and Cu at energies between 160 keV and 2.0 MeV into single crystals of MgO (100) at room temperature. The formation of nanoclusters was confirmed using photospectrometry, in combination with Mie's theory, which was indirect but nondestructive. Using Doyle's theory, as well as Rutherford Backscattering Spectrometry (RBS), we correlated the full width half maximum of the absorption bands to the estimated size of the metallic nanoclusters between 1–10 nm. These clusters were formed both by over implantation and by a combination of threshold fluence of the implanted species and post thermal annealing. The changes in the estimated size of the nanoclusters, after annealing at temperatures ranging from 500°C to 1000°C, were observed using photospectrometry.

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