Anomalous effect of magnetic breakdown on the oscillatory magnetization

1985 ◽  
Vol 400 (1818) ◽  
pp. 145-161 ◽  
Keyword(s):  
Orbit Interaction ◽  
Energy Band Structure ◽  
Field Amplitude ◽  
Conventional Theory ◽  
Anomalous Effect ◽  
Quantum Oscillations ◽  
Magnetic Breakdown ◽  
Field Modulation ◽  
The Magnetic Field ◽  
Good Agreement

It is shown that the effect of magnetic breakdown on the oscillatory magnetization in metals can vary dramatically from that predicted by conventional theory. We report a detailed study of the amplitude of the de Haas–van Alphen (d. H. v. A.) magnetization of the magnetic breakdown β orbit in aluminium, which exhibits unexpected behaviour as a function of the magnitude and orientation of the magnetic field. Amplitude measurements have been made by using a sensitive field-modulation technique in which the interference, in particular, from quantum oscillations in the conductivity, could be reliably separated out. A generalized model for the effect of magnetic breakdown on the amplitude has been developed to explain these results. Calculations of the amplitude based on this model, with the use of breakdown fields deduced from an energy band structure including the spin–orbit interaction, are found to be in good agreement with experiment. The new model indicates that when breakdown is important, the d. H. v. A. frequency is not determined in general by an extremal cross section of the Fermi surface, as is conventionally assumed.

A study of the quantum oscillations in the thermopower of molybdenum

1982 ◽  
Vol 60 (2) ◽  
pp. 122-130 ◽  
Author(s):  
R. Fletcher
Keyword(s):  
Liquid Helium ◽  
Field Dependence ◽  
Large Amplitude ◽  
Experimental Results ◽  
Quantum Oscillations ◽  
Magnetic Breakdown ◽  
Good Agreement

This paper is concerned with quantum oscillations in the thermoelectric coefficients of metals which do not undergo magnetic breakdown, and in particular focuses on the compensated metal Mo. An expression for the amplitude of the oscillations in the thermopower has been developed and is tested using a detailed set of experimental results on Mo taken with [Formula: see text] over the range 1.5–8 T at liquid helium temperatures. Good agreement is obtained for the temperature and field dependence, and absolute amplitudes are predicted to within a factor near unity. Oscillations of appreciable amplitude arc neither expected nor observed in the Nernst–Ettingshausen (N.E.) coefficient of Mo. Available thermopower data on In have also been analysed; it is concluded that, contrary to a previous speculation. In does not undergo magnetic breakdown at fields of the order of 2 T. It is suggested that, contrary to the thermopower. the N.E. coefficient will provide an unambiguous test for the occurrence of breakdown in metals since it is expected to exhibit large amplitude quantum oscillations only under breakdown conditions.

THE STUDY OF THE MAGNETIC BREAKDOWN EFFECT AS A FUNCTION OF ANGLE IN THE ORGANIC CONDUCTOR K- (BEDT-TTF)2Cu(NCS)2 IN HIGH MAGNETIC FIELDS

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3355-3359
Author(s):  
I. MIHUT ◽  
C. C. AGOSTA ◽  
C. H. MIELKE ◽  
M. TOKOMOTO
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Spin Splitting ◽  
High Magnetic Fields ◽  
Organic Conductor ◽  
Cross Sectional ◽  
Tank Circuit ◽  
Quantum Oscillations ◽  
Magnetic Breakdown ◽  
Splitting Factor

The magnetic breakdown effect can be seen by the growth of new frequencies in the quantum oscillations in clean metals as a function of magnetic field. We have studied the variation of the amplitudes in the quantum oscillations in the resistance (the Shubnikov-de Haas effect) as a function of angle in the quasi-two dimensional-organic conductor κ-(BEDT-TTF)2Cu(NCS)2. The measurements were made by means of a radio frequency (rf) tank circuit (~ 50 MHz) at very high magnetic fields(50T-60T) and low temperature(500 mK). The geometry of the rf excitation we used excited in-plane currents, and therefore we measured the in-plane resistivity. In contrast to conventional transport measurements that measure the inter-plane resistivity, the in-plane resistivity is dominated by the magnetic breakdown frequencies. As a result we measured much higher breakdown frequency amplitudes than conventional transport experiments. As is expected, the angular dependence of the Shubnikov-de Haas frequencies have a 1/cosθ behavior. This is due to the change of the cross sectional area of the tubular Fermi surface as the angle with respect to the magnetic field is changed. The amplitude of the oscillations changes due to the spin splitting factor which takes into account the ratio between the spin splitting and the energy spacing of the Landau levels which also has 1/cosθ behavior. We show that our data agree with the semi-classical theory (Lifshitz-Kosevich formula).

Doppler-Shifted Cyclotron Resonance in Thin Metal Films

1972 ◽  
Vol 50 (18) ◽  
pp. 2122-2137
Author(s):  
R. Turner ◽  
J. F. Cochran
Keyword(s):  
Magnetic Field ◽  
Metal Films ◽  
Thin Metal Film ◽  
Thin Metal ◽  
Free Electrons ◽  
Fermi Surfaces ◽  
First Order ◽  
Simple Quantum ◽  
The Magnetic Field ◽  
Good Agreement

According to Van Gelder the microwave absorption by a thin metal film in the presence of a static magnetic field normal to the film contains a series of peaks as the magnetic field is varied. In the present paper it is argued that these peaks correspond to Doppler-shifted cyclotron resonances of the carriers in the metal due to the quantization of electron momenta normal to the plane of the film. A simple quantum calculation is presented for the case of free electrons where the film is thin enough that to first order the microwave fields within are determined only by the boundary conditions and Maxwell's equations. The quantum expression is in good agreement with the absorption calculated using semiclassical arguments which can be readily extended to more complicated Fermi surfaces.

scholarly journals Experimental and numerical investigation of plasma parameters in the magnetosheath

2018 ◽  
Vol 145 ◽  
pp. 03003
Author(s):  
Polya Dobreva ◽  
Monio Kartalev ◽  
Olga Nitcheva ◽  
Natalia Borodkova ◽  
Georgy Zastenker
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Numerical Investigation ◽  
Euler Equations ◽  
Ideal Gas ◽  
Bow Shock ◽  
Plasma Parameters ◽  
Wind Spacecraft ◽  
The Magnetic Field ◽  
Good Agreement

We investigate the behaviour of the plasma parameters in the magnetosheath in a case when Interball-1 satellite stayed in the magnetosheath, crossing the tail magnetopause. In our analysis we apply the numerical magnetosheath-magnetosphere model as a theoretical tool. The bow shock and the magnetopause are self-consistently determined in the process of the solution. The flow in the magnetosheath is governed by the Euler equations of compressible ideal gas. The magnetic field in the magnetosphere is calculated by a variant of the Tsyganenko model, modified to account for an asymmetric magnetopause. Also, the magnetopause currents in Tsyganenko model are replaced by numericaly calulated ones. Measurements from WIND spacecraft are used as a solar wind monitor. The results demonstrate a good agreement between the model-calculated and measured values of the parameters under investigation.

scholarly journals Quantum Oscillations and Chiral Anomaly in a Bi0.96Sb0.04 Single Crystal

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Gongqin Xu ◽  
Anne de Visser ◽  
Yingkai Huang ◽  
Xingyu Mao
Keyword(s):  
Electrical Current ◽  
Band Edge ◽  
Chiral Anomaly ◽  
Conduction Band Edge ◽  
Special Significance ◽  
Weak Antilocalization ◽  
Quantum Oscillations ◽  
The Magnetic Field ◽  
Haas Effect ◽  
Topological Term

Bi1-xSbx alloys are of special significance in topological insulator research. Here we focus on the Bi0.96Sb0.04 alloy in which the conduction band edge just touches the valence band edge. Transport measurements show quantum oscillations in the longitudinal (Shubnikov–de Haas effect) and transverse magnetoresistance originating from a spheroidal Fermi surface pocket. Further investigation of the longitudinal magnetoresistance for the magnetic field parallel to the electrical current shows a small nonmonotonic magnetoresistance that is attributed to a competition of weak-antilocalization effects and a topological term related to the chiral anomaly.

scholarly journals Описание колоссального магнитосопротивления La-=SUB=-1.2-=/SUB=-Sr-=SUB=-1.8-=/SUB=-Mn-=SUB=-2-=/SUB=-O-=SUB=-7-=/SUB=- на основе "спин-поляронного" и "ориентационного" механизмов проводимости в парамагнитной области температур

2020 ◽  
Vol 62 (5) ◽  
pp. 669
Author(s):  
С.А. Гудин ◽  
Н.И. Солин
Keyword(s):  
Magnetic Field ◽  
Colossal Magnetoresistance ◽  
Main Role ◽  
Spin Polaron ◽  
Temperature Range ◽  
Conduction Mechanisms ◽  
Theoretical Investigations ◽  
Temperature Dependences ◽  
The Magnetic Field ◽  
Good Agreement

Experimental and theoretical investigations of the resistance of the La1.2Sr1.8Mn2O7 single crystal in magnetic fields from 0 to 90 kOe and in the temperature range from 75 to 300 K has been studied. The magnetoresistance is determined by the “spin-polaron” and “orientation” conduction mechanisms. Using the method of separating contributions to the magnetoresistance from several conduction mechanisms, the observed magnetoresistance of La1.2Sr1.8Mn2O7 manganite in the temperature range of 75-300 K is described, good agreement between the calculated and experimental data is obtained. In a magnetic field of 0 and 90 kOe, the temperature dependences of the size of the spin polaron (in relative units) are calculated for the temperature range 75–300 K. It is shown, that the КМС value is determined by an increase in the linear size of the spin polaron (along the magnetic field), i.e. the main role in the magnitude of the colossal magnetoresistance is made by the change in the size of the magnetic inhomogeneities of the crystal.

scholarly journals Quantum oscillations, magnetic breakdown and thermal Hall effect in Co3Sn2S2

2021 ◽  
Author(s):  
Linchao Ding ◽  
Jahyun Koo ◽  
Changjiang Yi ◽  
Liangcai Xu ◽  
Huakun Zuo ◽  
...  
Keyword(s):  
Hall Effect ◽  
Quantum Oscillations ◽  
Magnetic Breakdown

scholarly journals Квантовые осцилляции релаксации фотопроводимости в p-i-n-гетеродиодах GaAs/InAs/AlAs

2018 ◽  
Vol 52 (6) ◽  
pp. 591
Author(s):  
Ю.Н. Ханин ◽  
Е.Е. Вдовин
Keyword(s):  
Magnetic Field ◽  
Quantum Well ◽  
Oscillation Amplitude ◽  
Light Flux ◽  
Quantum Oscillations ◽  
Ballistic Motion ◽  
The Common ◽  
Relaxation Curves ◽  
Relaxation Characteristics ◽  
The Magnetic Field

AbstractThe photoconductivity and its relaxation characteristics in tunneling p – i – n GaAs/AlAs heterostructures under pulsed illumination is studied. Quantum oscillations in the photoconductivity are detected depending on the bias voltage with the period independent of the light wavelength, as well as an oscillating component of the relaxation curves caused by modulation of the recombination rate at the edge of a triangular quantum well in the undoped i layer, as in the case of photoconductivity oscillations. The common nature of oscillations of the steady-state photoconductivity and relaxation curves under pulsed illumination is directly confirmed by the lack of an oscillating component in both types of dependences of some studied p–i–n heterostructures. Simultaneous suppression of the observed oscillations of dependences of both types as the temperature increases to 80 K also confirms the proposed mechanism of their formation. The dependences of these oscillations on the magnetic field and light flux power are studied. Oscillation-amplitude suppression in a magnetic field of ~2 T perpendicular to the current is caused by the effect of the Lorentz force on the ballistic motion of carriers in the triangular-quantum-well region.

On the evolution of a nonlinear Alfvén pulse

1999 ◽  
Vol 62 (2) ◽  
pp. 219-232 ◽  
Author(s):  
E. VERWICHTE ◽  
V. M. NAKARIAKOV ◽  
A. W. LONGBOTTOM
Keyword(s):  
Temporal Evolution ◽  
Transverse Velocity ◽  
Longitudinal Velocity ◽  
Initial Pulse ◽  
Weakly Nonlinear ◽  
Starting Position ◽  
Linearly Polarized ◽  
Nonlinear Plane ◽  
The Magnetic Field ◽  
Good Agreement

The temporal evolution of weakly nonlinear, plane, linearly polarized Alfvén pulses in a cold homogeneous plasma is investigated. A static initial pulse-like disturbance in transverse velocity produces two Alfvén pulses that travel in opposite directions along the magnetic field. The ponderomotive force of the two pulses produces a static shock in longitudinal velocity at the starting position. The travelling pulses form a shock front that is governed by the scalar Cohen–Kulsrud equation. We find good agreement between the analytical solutions we derive and the results from a fully nonlinear numerical MHD code.

Viscomagnetic Heat Flux Experiments as a Test of Gas Kinetic Theory in the Burnett Regime

1978 ◽  
Vol 33 (7) ◽  
pp. 749-760 ◽  
Author(s):  
G. E. J. Eggermont ◽  
P. W. Hermans ◽  
L. J. F. Hermans ◽  
H. F. P. Knaap ◽  
J. J. M. Beenakker
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Heat Flux ◽  
External Magnetic Field ◽  
Room Temperature ◽  
Flow Direction ◽  
Rectangular Channel ◽  
Gas Kinetic Theory ◽  
The Magnetic Field ◽  
Good Agreement

In a rarefied polyatomic gas streaming through a rectangular channel, an external magnetic field produces a heat flux perpendicular to the flow direction. Experiments on this “viscom agnetic heat flux” have been performed for CO, N2, CH4 and HD at room temperature, with different orientations of the magnetic field. Such measurements enable one to separate the boundary layer contribution from the purely bulk contribution by means of the theory recently developed by Vestner. Very good agreement is found between the experimentally determined bulk contribution and the theoretical Burnett value for CO, N2 and CH4 , yet the behavior of HD is found to be anomalous.

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