Unusually Large Change in Radiative Lifetime of theA-Band Emission in KI:In+and KI:Sn2+Induced by a Magnetic Field

1972 ◽  
Vol 28 (16) ◽  
pp. 1032-1034 ◽  
Author(s):  
Atsuo Fukuda ◽  
Philip Yuster
Keyword(s):  
Magnetic Field ◽  
Radiative Lifetime ◽  
Large Change ◽  
Band Emission

scholarly journals The theory of the galvomagnetic effects in bismuth

1936 ◽  
Vol 155 (886) ◽  
pp. 653-663 ◽  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Air Temperature ◽  
Solid Solutions ◽  
Hall Coefficient ◽  
Specific Resistance ◽  
Large Change ◽  
Free Electrons ◽  
The Magnetic Field ◽  
Positive Holes

The change in the specific resistance of bismuth when subject to a magnetic field is far greater than that of most metals, e . g ., a field of 10 kilo-gauss, at liquid air temperature, increases the resistance of bismuth eightfold, whilst the same field causes an increase of only 0·1% in the resistance of silver. Besides the large change of resistance it is found that the Hall coefficient of bismuth is also much greater than of most metals, and shows a curious dependence upon on the magnetic field strength, as well as a very striking temperature dependence. In this paper these effects are considered on the basis of a theory previously of bismuth, and the properties of the dilute solid solutions of other elements in bismuth.* It was shown that in bismuth the relation between the structure and the available number of valency electrons was such that these electrons formed an almost closed group, or in other words an almost completely filled Brillouin zone. In such a case an electric current is carried by a number (in bismuth a very small number) of electrons, and an equal number of positive holes. By positive holes we mean the few vacant places which are left when a zone or energy band is almost completely filled. These vacancies behave like positive charges; their effective mass is, in general, smaller than that of free electrons.

Effect of External Fields on the Martensitic Transformation in Ni-Mn Based Heusler Alloys

2008 ◽  
Vol 52 ◽  
pp. 189-197 ◽  
Author(s):  
Xavier Moya ◽  
Lluís Mañosa ◽  
Antoni Planes ◽  
Seda Aksoy ◽  
Mehmet Acet ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Hydrostatic Pressure ◽  
Martensitic Transformation ◽  
Applied Magnetic Field ◽  
Heusler Alloys ◽  
Applied Pressure ◽  
Large Change ◽  
Entropy Change ◽  
Martensitic Transition ◽  
External Fields

In this paper, we discuss the possibility of inducing a martensitic transition by means of an applied magnetic field or hydrostatic pressure in Ni-Mn based Heusler shape memory alloys. We report on the shift of the martensitic transition temperatures with applied magnetic field and applied pressure and we show that it is possible to induce the structural transformation in a Ni50Mn34In16 alloy by means of both external fields due to: (i) the low value of the entropy change and (ii) the large change of magnetization and volume, which occur at the martensitic transition.

On Hanle Effects in the B(3Σu−)–X(3Σg−) Band System of the Se2 Molecule

1975 ◽  
Vol 53 (2) ◽  
pp. 140-144 ◽  
Author(s):  
F. W. Dalby ◽  
J. Vigué ◽  
J. C. Lehmann
Keyword(s):  
Magnetic Field ◽  
Excited States ◽  
Band System ◽  
Radiative Lifetime ◽  
Argon Laser ◽  
Level Crossing ◽  
G Factor ◽  
Field Level

Magnetic field level crossing has been studied for the excited states of 80Se2 produced by absorption of the 4880, 4765, and 4727 Å lines of an argon laser. The product of the radiative lifetime and the Lande g factor, gτ, together with the sign of the g factor, has been determined for each of the levels. An identification of the previously unobserved transition produced by 4727 Å excitation is presented.

External magnetic field effects on the β band emission of NO

1991 ◽  
Vol 94 (3) ◽  
pp. 1923-1928 ◽  
Author(s):  
M. Sumitani ◽  
H. Abe ◽  
S. Nagakura
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Field Effects ◽  
Field Effects ◽  
Band Emission

scholarly journals Narrow-band emission with 0.5 to 3.5 Hz varying frequency in the background of the main phase of the 17 March 2013 magnetic storm

2016 ◽  
Vol 2 (4) ◽  
pp. 13-23
Author(s):  
Александр Потапов ◽  
Alexander Potapov ◽  
Борис Довбня ◽  
Boris Dovbnya ◽  
Дмитрий Баишев ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Storm ◽  
Carrier Frequency ◽  
Narrow Band ◽  
Vertical Component ◽  
Main Phase ◽  
Ion Fluxes ◽  
Emission Frequency ◽  
Band Emission ◽  
Generation Region

We present results of the analysis of an unusually long narrow-band emission in the Pc1 range with increasing carrier frequency. The event was observed against the background of the main phase of a strong magnetic storm caused by arrival of a high-speed solar wind stream with a shock wave in the stream head and a long interval of negative vertical component of the interplanetary magnetic field. Emission of approximately 9-hour duration had a local character, appearing only at three stations located in the range of geographical longitude λ=100–130 E and magnetic shells L=2.2–3.4. The signal carrier frequency grew in a stepped mode from 0.5 to 3.5 Hz. We propose an emission interpretation based on the standard model of the generation of ion cyclotron waves in the magnetosphere due to the resonant wave-particle interaction with ion fluxes of moderate energies. We suppose that a continuous shift of the generation region, located in the outer area of the plasmasphere, to smaller L-shell is able to explain both the phenomenon locality and the range of the frequency increase. A narrow emission frequency band is associated with the formation of nose-like structures in the energy spectrum of the ion fluxes penetrating from the geomagnetic tail into magnetosphere. We offer a possible speculative scenario of the processes leading to the generation of the observed emission. The scenario contains specific values of the generation region position, plasma density, magnetic field, and resonant proton energies. We discuss morphological differences of the emissions considered from known types of geomagnetic pulsations, and reasons for the occurrence of this unusual event.

scholarly journals ANISOTROPIC DEPENDENCE OF GIANT MAGNETO-IMPEDANCE OF AN AMORPHOUS FERROMAGNETIC RIBBON ON BIASING FIELD

2007 ◽  
Vol 21 (22) ◽  
pp. 3859-3867
Author(s):  
B. KAVIRAJ ◽  
S. K. GHATAK
Keyword(s):  
Magnetic Field ◽  
Room Temperature ◽  
Amorphous Ribbon ◽  
Large Change ◽  
Nominal Composition ◽  
Large Drop ◽  
Giant Magneto Impedance ◽  
Dc Biasing ◽  
Ac Fields ◽  
The Magnetic Field

The magneto-impedance (MI) in an amorphous ribbon of nominal composition Fe 73.5 Nb 3 Cu 1 Si 13.5 B 9 has been measured at 1 MHz at room temperature for different configurations of exciting AC and biasing DC fields. A large drop in both resistance and reactance is observed as a function of the magnetic field. When the DC and AC fields are parallel but normal to the axis of the ribbon, a smaller magnetic field is needed to reduce the impedance to its small saturated value compared to the situation when the fields are along the axis of the ribbon. A larger DC field is required to lower the impedance when the DC field acts perpendicularly to the plane of the ribbon. Such anisotropy in magneto-impedance is related to the anisotropic response of the magnetization of the ribbon. The large change of impedance is attributed to a large variation of AC permeability on the direction and magnitude of the DC biasing field.

SEMPA Studies of Exchange Coupling in Magnetic Multilayers

MRS Bulletin ◽  
1995 ◽  
Vol 20 (10) ◽  
pp. 30-33 ◽  
Author(s):  
R.J. Celotta ◽  
D.T. Pierce ◽  
J. Unguris
Keyword(s):  
Magnetic Field ◽  
Exchange Coupling ◽  
Giant Magnetoresistance ◽  
Large Change ◽  
Magnetic Multilayers ◽  
Information Storage ◽  
Conduction Electrons ◽  
Spacer Layer ◽  
Ferromagnetic Layers ◽  
Oscillatory Coupling

In the late 1980s, a number of exciting yet puzzling observations resulted from experiments investigating the coupling between two ferromagnetic layers separated by a nonferromagnetic spacer layer. A pioneering experiment by Grünberg et al. showed that Fe layers separated by a thin Cr spacer aligned with antiparallel magnetization, but with Au as the spacer layer, a parallel alignment occurred. The long-range magnetic dipole from each layer would tend to explain antiparallel alignment; small pinholes in the spacer layer would produce parallel alignment. Alternatively, the layers might be coupled through the spacer-layer conduction electrons by the Ruder man-Kittel-Kasuya-Yosida (RKKY) effect. This was expected to produce an oscillation in coupling as the spacer thickness increased, that is, an oscillation between parallel and antiparallel alignment. Oscillatory coupling was first observed by Parkin et al. Researchers had also found that, at spacer thicknesses where antiparallel alignment occurred, the Fe/Cr/Fe system can exhibit a giant magnetoresistance (GMR) effect, that is, an anomalously large change in resistance when a magnetic field is applied. The potential technological importance of the GMR effect to magnetic sensing and magnetic information storage added further impetus to the already rapidly growing area of research in magnetic multilayers.

scholarly journals INFLUENCE OF SATURATION MAGNETIZATION AND VISCOSITY ON SPECIFIC LOSS POWER FOR CoFe2O4 AND MnFe2O4 MAGNETIC NANOPARTICLES

2018 ◽  
Vol 54 (1A) ◽  
pp. 33
Author(s):  
Luu Huu Nguyen
Keyword(s):  
Magnetic Field ◽  
Magnetic Nanoparticles ◽  
Saturation Magnetization ◽  
Large Change ◽  
Specific Loss ◽  
Heating Source ◽  
Specific Loss Power ◽  
Brown Relaxation ◽  
Soft Ferrite ◽  
Viscosity Changes

Magnetic nanoparticles absorb energy from external alternating magnetic field to create ananosized heating source. Specific loss power (SLP) is affected strongly by several magneticparameters of material and viscosity of nanofluid. In this study, the specific loss power asdependent on saturation magnetization was calculated for hard ferrite CoFe2O4 (K = 290 kJ/m3)and soft ferrite MnFe2O4 (K = 3 kJ/m3) with two values of viscosity in biological range 1-2 mPas.Besides, we investigated the experimental dependence SLP on their saturation magnetizationwhile changing viscosity using agar powder. A large change of slopesSLPMwas found for CFOwhen the viscosity changes; whereas it remained almost unaffected by the variation of viscosityfluid of MFO. All calculation and experimental results are discussed via the competitionbetween Néel and Brown relaxation.

scholarly journals Narrow-band emission with 0.5 to 3.5 Hz varying frequency in the background of the main phase of the 17 March 2013 magnetic storm

2017 ◽  
Vol 2 (4) ◽  
pp. 16-30 ◽  
Author(s):  
Александр Потапов ◽  
Alexander Potapov ◽  
Борис Довбня ◽  
Boris Dovbnya ◽  
Дмитрий Баишев ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Storm ◽  
Carrier Frequency ◽  
Narrow Band ◽  
Vertical Component ◽  
Main Phase ◽  
Ion Fluxes ◽  
Emission Frequency ◽  
Band Emission ◽  
Generation Region

We present results of the analysis of an unusually long narrow-band emission in the Pc1 range with increasing carrier frequency. The event was observed against the background of the main phase of a strong magnetic storm caused by arrival of a high-speed solar wind stream with a shock wave in the stream head and a long interval of negative vertical component of the interplanetary magnetic field. Emission of approximately 9-hour duration had a local character, appearing only at three stations located in the range of geographical longitude λ=100–130 E and magnetic shells L=2.2–3.4. The signal carrier frequency grew in a stepped mode from 0.5 to 3.5 Hz. We propose an emission interpreta-tion based on the standard model of the generation of ion cyclotron waves in the magnetosphere due to the resonant wave-particle interaction with ion fluxes of moderate energies. We suppose that a continuous shift of the generation region, located in the outer area of the plasmasphere, to smaller L-shell is able to explain both the phenomenon locality and the range of the frequency increase. A narrow emission frequency band is associated with the formation of nose-like structures in the energy spectrum of ion fluxes penetrating from the geomagnetic tail into the magnetosphere. We offer a possible scenario of the processes leading to the generation of the observed emission. The scenario contains specific values of the generation region position, plasma density, magnetic field, and resonant proton energies. We discuss morphological differences of the emissions considered from known types of geomagnetic pulsations, and reasons for the occurrence of this unusual event.

ELECTROMAGNETIC CASCADES IN MAGNETIZED MEDIA

2010 ◽  
Vol 19 (06) ◽  
pp. 671-676 ◽  
Author(s):  
LEONARDO J. PELLIZZA ◽  
MARIANA ORELLANA ◽  
GUSTAVO E. ROMERO
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Weak Magnetic Field ◽  
Numerical Scheme ◽  
Gamma Ray ◽  
Broad Band ◽  
Broad Band Emission ◽  
Band Emission ◽  
Self Consistent ◽  
Open Issue

The investigation of the astrophysical nature of gamma-ray sources and the processes responsible for their broad-band emission requires a detailed modeling of their observable spectrum, in which electromagnetic cascades can play an important role. An open issue in this modeling is the effect of magnetic fields in the development of cascades. In this paper we present a novel numerical scheme to compute this effect in a self-consistent way. Applied to a toy model, our scheme reproduces the features expected for cascades in the strong and weak magnetic field regimes.

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