REENTRANT-LIKE BAND JAHN–TELLER EFFECT AND ITS FIELD DEPENDENCE

2008 ◽  
Vol 22 (04) ◽  
pp. 423-434 ◽  
Author(s):  
G. GANGADHAR REDDY ◽  
T. VENKATAPPA RAO ◽  
A. RAMAKANTH ◽  
S. K. GHATAK ◽  
S. N. BEHERA
Keyword(s):  
Magnetic Field ◽  
Parameter Space ◽  
Structural Transition ◽  
Lattice Strain ◽  
Universal Function ◽  
Electronic Energy ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
The Difference ◽  
The Magnetic Field

In the presence of the electron–lattice interaction where the lattice strain is coupled to the difference in orbital occupancy, the metallic system whose Fermi level lies in an orbitally degenerate eg band undergoes a structural transition to a lower symmetric state with distortion. The distortion is the consequence of the band Jahn–Teller (J–T) effect, and results from the gain of the electronic energy against the increase in the elastic energy. The extent of distortion depends on the nature of the density of states (DOS) and carrier concentration. These effects are examined for a system described by a different model DOS, and an orbitally degenerate eg band with the J–T interaction. In a certain region of parameter space, the temperature dependence of distortion exhibits a reentrant-like behavior, and the magnetic field augments the distortion in this region. In the parameter space where there is no reentrant-like behavior, the field suppresses the distortion, and the normalized distortion becomes a universal function of the normalized field. A phase diagram is obtained in the magnetic field–temperature plane.

Relaxation Attenuation of Ultrasound by the Jahn-Teller Centers in ZnSe:Cr in High Magnetic Fields

2015 ◽  
Vol 233-234 ◽  
pp. 125-128 ◽  
Author(s):  
N.S. Averkiev ◽  
I.B. Bersuker ◽  
V.V. Gudkov ◽  
S. Zherlitsyn ◽  
S. Yasin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Ultrasonic Attenuation ◽  
Energy Levels ◽  
Orbital Interaction ◽  
Spin Orbital ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
The Magnetic Field ◽  
Good Agreement

The magnetic field dependence of ultrasonic attenuation α (B) of slow shear waves in the ZnSe:Cr2+crystal at a number of fixed temperatures fromT=1.4 K to 20 K in magnetic fields of up toB=14 T were investigated. For magnetic fieldsBabove 5 T we found that the attenuation increases with B monotonically, and at a given temperature it is proportional to the magnitude of relaxation attenuation atB=0. We show that the magnetic field dependent attenuation is due to the change in populations of the lowest energy levels of the impurity centers CrZn4Se, produced by the Jahn-Teller effect and split by the spin-orbital interaction and the magnetic field. The calculations carried out without fitting parameters are in good agreement with the experimental data.

scholarly journals First in-orbit results of the vector magnetic field measurement of the High Precision Magnetometer onboard the China Seismo-Electromagnetic Satellite

2019 ◽  
Vol 71 (1) ◽  
Author(s):  
Bin Zhou ◽  
Bingjun Cheng ◽  
Xiaochen Gou ◽  
Lei Li ◽  
Yiteng Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Precision ◽  
Magnetic Field Measurement ◽  
Vector Data ◽  
Magnetic Field Data ◽  
Night Side ◽  
The Difference ◽  
The Magnetic Field ◽  
Ground Calibration ◽  
Data Calibration

Abstract The High Precision Magnetometer (HPM) is one of the main payloads onboard the China Seismo-Electromagnetic Satellite (CSES). The HPM consists of two Fluxgate Magnetometers (FGM) and the Coupled Dark State Magnetometer (CDSM), and measures the magnetic field from DC to 15 Hz. The FGMs measure the vector components of the magnetic field; while the CDSM detects the magnitude of the magnetic field with higher accuracy, which can be used to calibrate the linear parameters of the FGM. In this paper, brief descriptions of measurement principles and performances of the HPM, ground, and in-orbit calibration results of the FGMs are presented, including the thermal drift and magnetic interferences from the satellite. The HPM in-orbit vector data calibration includes two steps: sensor non-linearity corrections based on on-ground calibration and fluxgate linear parameter calibration based on the CDSM measurements. The calibration results show a reasonably good stability of the linear parameters over time. The difference between the field magnitude calculated from the calibrated FGM components and the magnitude directly measured by the CDSM is just 0.5 nT (1σ) when the linear parameters are fitted separately for the day- and the night-side. Satellite disturbances have been analyzed including soft and hard remanence as well as magnetization of the magnetic torquer, radiation from the Tri-Band Beacon, and interferences from the rotation of the solar wing. A comparison shows consistency between the HPM and SWARM magnetic field data. Observation examples are introduced in the paper, which show that HPM data can be used to survey the global geomagnetic field and monitor the magnetic field disturbances in the ionosphere.

The Magnetic Anisotropy of Stretched Rubber as a Function of the Tension to Which It Is Subjected

1945 ◽  
Vol 18 (1) ◽  
pp. 8-9 ◽  
Author(s):  
Eugénie Cotton-Feytis
Keyword(s):  
Magnetic Field ◽  
Magnetic Anisotropy ◽  
Uniaxial Crystal ◽  
Horizontal Magnetic Field ◽  
First Approximation ◽  
The Difference ◽  
The Times ◽  
Angular Displacements ◽  
The Magnetic Field ◽  
Oscillation Method

Abstract From the standpoint of its magnetic anisotropy, stretched rubber is comparable in a first approximation to a uniaxial crystal, in which the direction of the axis is the same as the direction of elongation. It is possible to measure this anisotropy by means of the oscillation method used by Krishnan, Guha and Banerjee in studying crystals. The sample to be examined is suspended in a uniform horizontal magnetic field in such a manner that its axis is horizontal. It is then so arranged that the torsion of the suspension wire is zero when the rubber sample is in a position of equilibrium in the field. The times of oscillation T′ and T for very small angular displacements around this position, in the presence and then in the absence of the magnetic field, are then recorded. In this way the difference between the specific susceptibilities in the direction of the axis and in the horizontal direction perpendicular to the axis is calculated by application of the equation:

Effect of a static magnetic field onEscherichia coliadhesion and orientation

2016 ◽  
Vol 62 (11) ◽  
pp. 944-952 ◽  
Author(s):  
Lotfi Mhamdi ◽  
Nejib Mhamdi ◽  
Naceur Mhamdi ◽  
Philippe Lejeune ◽  
Nicole Jaffrezic ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Bacterial Adhesion ◽  
Parallel Magnetic Field ◽  
Field Orientation ◽  
Static Magnetic Fields ◽  
Preliminary Study ◽  
The Difference ◽  
The Magnetic Field

This preliminary study focused on the effect of exposure to 0.5 T static magnetic fields on Escherichia coli adhesion and orientation. We investigated the difference in bacterial adhesion on the surface of glass and indium tin oxide-coated glass when exposed to a magnetic field either perpendicular or parallel to the adhesion surface (vectors of magnetic induction are perpendicular or parallel to the adhesion surface, respectively). Control cultures were simultaneously grown under identical conditions but without exposure to the magnetic field. We observed a decrease in cell adhesion after exposure to the magnetic field. Orientation of bacteria cells was affected after exposure to a parallel magnetic field. On the other hand, no effect on the orientation of bacteria cells was observed after exposure to a perpendicular magnetic field.

V.—Dissymmetrical Separations in the Zeeman Effect in Tungsten and Molybdenum

1909 ◽  
Vol 29 ◽  
pp. 75-83 ◽  
Author(s):  
Robert Jack
Keyword(s):  
Magnetic Field ◽  
Wave Length ◽  
Zeeman Effect ◽  
Normal Type ◽  
Single Spectrum ◽  
Large Numbers ◽  
Middle Component ◽  
The Absolute ◽  
The Difference ◽  
The Magnetic Field

It has been mentioned by Professor Voigt of Göttingen in his newly published book and by Professor Zeeman of Amsterdam in the Physikalische Zeitschrift, that I have found examples of strongly marked dissymmetry in studying the Zeeman Effect in tungsten and molybdenum. Professor Zeeman has also discovered and published such cases of dissymmetry in other elements. Not only have many examples of normal dissymmetry been found, but almost as many cases of abnormal dissymmetry. To explain those terms, normal and abnormal, let us consider that the single spectrum line is broken up, when the light is in the magnetic field, into the three components, 1, 2, 3, where the numbers begin from the component which has the shortest wave-length. In the normal dissymmetrical triplet the middle component is nearer the component on the red side than that on the violet one, i.e. for the normal type the interval 1–2 is greater than the interval 2–3, but in the abnormal dissymmetrical triplet 2 is nearer to 1 than to 3. These observations of Professor Zeeman and myself, which were made at the same time in the Universities of Amsterdam and Göttingen, having been communicated to Professor Voigt, he wrote and published in the above-mentioned book an extension to his and Professor H. A. Lorentz's theories of the Zeeman Effect. In his original theory Professor Voigt had shown that, considering the electrons as uncoupled, cases of normal dissymmetry might arise among the Zeeman triplets, this dissymmetry being accompanied by a greater intensity of the red component than the violet one. He pointed out also that the ‘absolute’ dissymmetry or the difference between the absolute displacements of the red and violet components should be independent of the magnetic field strength used to produce the Zeeman Effect. To explain the large numbers of complicated types of Zeeman Effect which have been found —in the study of the Zeeman Effect in tungsten I discovered lines with no fewer than 17 to 19 components, the largest numbers hitherto found—Professors Voigt and Lorentz made use in their theories of couplings between electrons of the same vibration frequencies.

Characteristics of Magneto-Rheological Elastomer under Stick-Slip Condition

2020 ◽  
Vol 842 ◽  
pp. 193-198
Author(s):  
Kwang Hee Lee ◽  
Chul Hee Lee
Keyword(s):  
Magnetic Field ◽  
Glass Plate ◽  
Static Friction ◽  
Low Noise ◽  
Friction Behavior ◽  
Stick Slip ◽  
The Difference ◽  
Magneto Rheological ◽  
Squeal Noise ◽  
The Magnetic Field

This paper examines the characteristics of stick-slip phenomena between the glass plate and Magneto-Rheological Elastomer (MRE) surface. Stick-slip phenomena are the spontaneous jerking motion that occurs while two objects are sliding over each other, usually accompanied by noise. Stick-slip is generated when it involves discontinuous frictional degradation when moving from static friction to dynamic friction. The phenomena can lead to uneven wear patterns, vibration and squeal noise which cause a shorter lifespan for the corresponding mechanical elements. MREs are kind of function materials to consist of a polymeric matrix with embedded ferromagnetic particles. Mechanical properties of the MREs can be controlled by the application of magnetic fields. The magnetic field-based controllability can be applied to the control of stick-slip phenomena. The friction experiment is conducted with the Reciprocating Friction Tester (RFT). The sliding speed of the RFT should be in low-speed conditions in order to make the stick-slips relatively easy to occur. A uniform magnetic field and a weight load are applied to the MRE sample to observe the effect of various experimental parameters on the movement of the stick-slip. In addition, frictional sounds due to the stick-slip phenomenon under different loads and magnetic field strength are measured and analyzed. The results of this experiment show that as the strength of the magnetic field increases, the difference in stiffness between the wipers-glass decreases, mitigating fricatives. The result is expected to be well applied to low-noise automotive wipers based on the controllability of friction behavior and squeal noise.

scholarly journals Shape of a slowly rotating star measured by asteroseismology

2016 ◽  
Vol 2 (11) ◽  
pp. e1601777 ◽  
Author(s):  
Laurent Gizon ◽  
Takashi Sekii ◽  
Masao Takata ◽  
Donald W. Kurtz ◽  
Hiromoto Shibahashi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Rotation Period ◽  
Solar Radius ◽  
Spherically Symmetric ◽  
Convective Envelope ◽  
Stellar Radius ◽  
Nearby Stars ◽  
The Difference ◽  
Rotating Star ◽  
The Magnetic Field

Stars are not perfectly spherically symmetric. They are deformed by rotation and magnetic fields. Until now, the study of stellar shapes has only been possible with optical interferometry for a few of the fastest-rotating nearby stars. We report an asteroseismic measurement, with much better precision than interferometry, of the asphericity of an A-type star with a rotation period of 100 days. Using the fact that different modes of oscillation probe different stellar latitudes, we infer a tiny but significant flattening of the star’s shape of ΔR/R = (1.8 ± 0.6) × 10−6. For a stellar radius R that is 2.24 times the solar radius, the difference in radius between the equator and the poles is ΔR = 3 ± 1 km. Because the observed ΔR/R is only one-third of the expected rotational oblateness, we conjecture the presence of a weak magnetic field on a star that does not have an extended convective envelope. This calls to question the origin of the magnetic field.

scholarly journals ERROR IN MEASURING THE MAGNETIC LIQUID MAGNETIZATION BY THE NUCLEAR MAGNETIC RESONANCE, CAUSED BY THE UNCERTAINTY OF THE EFFECTIVE FIELD CONSTANT

2021 ◽  
Vol 57 ◽  
pp. 15-18
Author(s):  
Alexander I. Zhernovoy ◽  
◽  
Ilya A. Yakimenko ◽  
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Effective Field ◽  
Magnetic Liquid ◽  
Different Shapes ◽  
The Difference ◽  
The Magnetic Field

The magnetic liquid magnetization is usually determined by measuring the magnetic field strength, which linearly depends on the effective field constant of the liquid and the demagnetization coefficient of the sample. The article proposes to measure the magnetic field strength, generated by the same magnetic liquid in the samples of different shapes, and to determine the magnetization relying on the difference in strength, generated by the samples of various shapes, taking advantage of the fact that the effective field constant does not depend on the shape of the sample

scholarly journals Changes with Height of Longitudinal Magnetic Field in Active Regions

1993 ◽  
Vol 141 ◽  
pp. 24-31
Author(s):  
S.I. Gopasyuk
Keyword(s):  
Magnetic Field ◽  
Field Intensity ◽  
Longitudinal Magnetic Field ◽  
Magnetic Field Intensity ◽  
Transverse Electric ◽  
Active Regions ◽  
Line Profiles ◽  
Current Value ◽  
The Difference ◽  
The Magnetic Field

Results of a study of longitudinal magnetic fields in active regions are presented. The observed magnetic field strength increases with height in the photosphere. The maximum of the magnetic field intensity coincides with the level where the central parts of λ5324,2 Å FeI and λ5269,5 FeI line profiles are formed. On the Hβ formation level the observed magnetic field intensity is smaller as compared with the potential one calculated on the basis of the observed field in FeI λ5253, 5Å line. The difference between the observed magnetic field and potential one is explained in terms of transverse electric currents. The current value can mount to 3×1011 A.

Visualization of magnetic field corresponding to acoustic signal and estimation of magnetic source based on symmetry of magnetic field distribution

2021 ◽  
Vol 263 (6) ◽  
pp. 610-618
Author(s):  
Takuto Kurosawa ◽  
Eri Ishizuka ◽  
Yasuhiro Oikawa ◽  
Minoru Konno ◽  
Masatoshi Asakawa ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Distribution ◽  
Acoustic Signal ◽  
Magnetic Field Distribution ◽  
Magnetic Source ◽  
The Difference ◽  
The Magnetic Field ◽  
The Invisible

A magnetic field corresponding to an acoustic signal is generated from an antenna, and by using a coil, can be again converted to an acoustic signal. It is possible to estimate where the invisible antenna is with the distribution of the received signal. The estimation is applied to a maintenance of a gas pipe on the situation that the distance from the entrance to a maintenance area is known, but piping route isn't. It is possible to identify maintenance areas of a gas pipe by inserting the antenna to it. The estimation has been done by listening to the received signal manually. However, it is difficult for people to identify accurate point because the difference in the volume for each places is subtle. To solve this problem, we visualized the distribution of the received signal, and estimated the magnetic field with only the acoustic signal. Then, we proposed a method to calculate where the invisible antenna is automatically by using symmetry of the distribution of the received signal.

Sign in / Sign up

Export Citation Format

Share Document