scholarly journals Simultaneous monitoring of singlet and triplet exciton variations in solid organic semiconductors driven by an external static magnetic field

2014 ◽  
Vol 105 (1) ◽  
pp. 013304 ◽  
Author(s):  
Baofu Ding ◽  
Kamal Alameh
Keyword(s):  
Magnetic Field ◽  
Organic Semiconductors ◽  
Static Magnetic Field ◽  
Triplet Exciton ◽  
External Static Magnetic Field

Experimental Tests of Possible Mechanisms for the Organic Magnetoresistive Effect

2007 ◽  
Vol 1032 ◽  
Author(s):  
Tho Duc Nguyen ◽  
James Rybicki ◽  
Yugang Sheng ◽  
Markus Wohlgenannt
Keyword(s):  
Magnetic Field ◽  
Organic Semiconductors ◽  
Electrode Materials ◽  
Spin Dynamics ◽  
Experimental Tests ◽  
Triplet Exciton ◽  
Side Chain ◽  
Singlet Exciton ◽  
Organic Magnetoresistance ◽  
Magnetoresistive Effect

AbstractWe experimentally test three existing models of organic magnetoresistance (OMAR) which are all based on carrier spin dynamics. We first prove that hyperfine field originating from the hydrogen nuclei in organic materials is necessary for observing OMAR by studying C60 sandwich devices using several different electrode materials. We show that C60, unlike many other organic semiconductors, does not exhibit any intrinsic OMAR effect. However, we find that as soon as the carriers in C60 are brought in proximity with hydrogen-containing compounds, either in the form of a polymeric electrode, or side-chain substituents, a weak OMAR effect is observed. Next, we perform charge-induced absorption and electroluminescence spectroscopy in a polyfluorene organic magnetoresistive device. Our experiments allow us to measure the singlet exciton, triplet exciton and polaron densities in a live device under an applied magnetic field, and to distinguish between three models of OMAR. These models are based on different spin-dependent interactions, namely exciton formation, triplet exciton-polaron quenching and bipolaron formation. We show that the singlet exciton, triplet exciton and polaron densities and conductivity all increase with increasing magnetic field. Our data are inconsistent with the exciton formation and triplet-exciton polaron quenching models.

Transmission interference tuned by an external static magnetic field in a two-slit structure

2009 ◽  
Vol 95 (12) ◽  
pp. 121103 ◽  
Author(s):  
Bin Hu ◽  
Ben-Yuan Gu ◽  
Yan Zhang ◽  
Ming Liu
Keyword(s):  
Magnetic Field ◽  
Static Magnetic Field ◽  
External Static Magnetic Field

scholarly journals A magnetoactive metamaterial based on a structured ferrite

2021 ◽  
Vol 26 (1) ◽  
pp. 28-34
Author(s):  
S. Polevoy ◽  
◽  
G. Kharchenko ◽  
S. Tarapov ◽  
O. Kravchuk ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Frequency Dependence ◽  
Static Magnetic Field ◽  
Groove Depth ◽  
Electromagnetic Properties ◽  
Saturation Field ◽  
External Static Magnetic Field ◽  
Spatial Geometry ◽  
Field Strengths

Subject and Purpose. The use of spatially structured ferromagnets is promising for designing materials with unique predetermined electromagnetic properties welcome to the development of magnetically controlled microwave and optical devices. The paper addresses the electromagnetic properties of structured ferrite samples of a different shape (spatial geometry) and is devoted to their research by the method of electron spin resonance (ESR). Methods and methodology. The research into magnetic properties of structured ferrite samples was performed by the ESR method. The measurements of transmission coefficient spectra were carried out inside a rectangular waveguide with an external magnetic field applied. Results. We have experimentally shown that over a range of external magnetic field strengths, the frequency of the ferromagnetic resonance (FMR) of grooved ferrite samples (groove type spatial geometry) increases with the groove depth. The FMR frequency depends also on the groove orientation relative to the long side of the sample. We have shown that as the external static magnetic field approaches the saturation field of the ferrite, the FMR frequency dependence on the external static magnetic field demonstrates "jump-like" behavior. And as the magnetic field exceeds the ferrite saturation field, the FMR frequency dependence on the groove depth gets a monotonic character and rises with the further growth of the field strength. Conclusion. We have shown that the use of structured ferrites as microwave electronics components becomes reasonable at magnetic field strengths exceeding the saturation field of the ferrite. At these fields, such a ferrite offers a monotonically increasing dependence of the resonant frequency on the external magnetic field and on the depth of grooves on the ferrite surface. Structured ferrites are promising in the microwave range as components of controlled filters, polarizers, anisotropic ferrite resonators since they can provide predetermined effective permeability and anisotropy

Effect of external static magnetic field on the particle distribution, the metallurgical process and the microhardness of Sn3.5Ag solder with magnetic Ni particles

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jianhua Wang ◽  
Hongbo Xu ◽  
Li Zhou ◽  
Ximing Liu ◽  
Hongyun Zhao
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Solder Joint ◽  
Magnetic Field Strength ◽  
Static Magnetic Field ◽  
Particle Distribution ◽  
Metallurgical Process ◽  
Content Type ◽  
Nickel Particles ◽  
External Static Magnetic Field

Purpose This paper aims to investigate the mechanism of Ni particles distribution in the liquid Sn3.5Ag melt under the external static magnetic field. The control steps of Ni particles and the Sn3.5Ag melt metallurgical process were studied. After aging, the microhardness of pure Sn3.5Ag, Sn3.5Ag containing randomly distributed Ni particles and Sn3.5Ag containing columnar Ni particles were compared. Design/methodology/approach Place the sample in a crucible for heating. After the sample melts, place a magnet directly above and below the sample to provide a magnetic field. Sn3.5Ag with the different morphological distribution of Ni particles was obtained by holding for different times under different magnetic field intensities. Finally, pure Sn3.5Ag, Sn3.5Ag with random distributed Ni particles and Sn3.5Ag with columnar Ni particles were aged and their microhardness was tested after aging. Findings The experimental results show that with the increase of magnetic field strength, the time for Ni particle distribution in Sn3.5Ag melt to reach equilibrium is shortened. After aging, the microhardness of Sn3.5Ag containing columnar nickel particles is higher than that of pure Sn3.5Ag and Sn3.5Ag containing randomly distributed nickel particles. A chemical reaction is the control step in the metallurgical process of nickel particles and molten Sn3.5Ag. Originality/value Under the action of the magnetic field, Ni particles in Sn3.5Ag melt will be arranged into columns. With the increase of magnetic field strength, the shorter the time for Ni particles in Sn3.5Ag melt to arrange in a column. With the extension of the service time of the solder joint, if Sn3.5Ag with columnar nickel particles is used as the solder joint material, its microhardness is better than Sn3.5Ag with arbitrarily distributed nickel particles and pure Sn3.5Ag.

scholarly journals Improvement of SiC Crystal Growth Rate and Uniformity via Top-Seeded Solution Growth under External Static Magnetic Field: A Numerical Investigation

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 651
Author(s):  
Minh-Tan Ha ◽  
Le Van Lich ◽  
Yun-Ji Shin ◽  
Si-Young Bae ◽  
Myung-Hyun Lee ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Fluid Flow ◽  
Crystal Growth ◽  
Static Magnetic Field ◽  
Crystal Surface ◽  
Solution Growth ◽  
Helmholtz Coils ◽  
External Static Magnetic Field ◽  
Top Seeded Solution Growth

Silicon carbide (SiC) is an ideal material for high-power and high-performance electronic applications. Top-seeded solution growth (TSSG) is considered as a potential method for bulk growth of high-quality SiC single crystals from the liquid phase source material. The crystal growth performance, such as growth rate and uniformity, is driven by the fluid flow and constitutional flux in the solution. In this study, we numerically investigate the contribution of the external static magnetic field generated by Helmholtz coils to the fluid flow in the silicon melt. Depending on the setup of the Helmholtz coils, four static magnetic field distributions are available, namely, uniform vertical upward/downward and vertical/horizontal cusp. Based on the calculated carbon flux coming to the crystal surface, the vertical downward magnetic field proved its ability to enhance the growth rate as well as the uniformity of the grown crystal.

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