Magnetic-field-induced sign reversal of transient photoreflectance inCd1−xMnxTe:Paramagnetic shift at low manganese concentration

1998 ◽  
Vol 58 (8) ◽  
pp. 4522-4530 ◽  
Author(s):  
W. Farah ◽  
D. Scalbert ◽  
M. Nawrocki ◽  
Yu. G. Semenov
Keyword(s):  
Magnetic Field ◽  
Manganese Concentration ◽  
Sign Reversal

Transient fields of a current loop source above a layered earth

Geophysics ◽  
1982 ◽  
Vol 47 (7) ◽  
pp. 1068-1077 ◽  
Author(s):  
G. M. Hoversten ◽  
H. F. Morrison
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Electric Fields ◽  
Current Loop ◽  
Wave Form ◽  
Sign Reversal ◽  
Circular Loop ◽  
Single Ring ◽  
Smoke Ring ◽  
A Current

The electric field induced within four layered models by a repetitive current wave form in a circular loop transmitter is presented along with the resulting magnetic fields observed on the surface. The behavior of the induced electric field as a function of time explains the observed sign reversal of the vertical magnetic field on the surface. In addition, the differences between magnetic field responses for different models are explained by the behavior of the induced electric fields. The pattern of the induced electric field is shown to be that of a single “smoke ring,” as described by Nabighian (1979), which is distorted by layering but which remains a single ring system rather than forming separate smoke rings in each layer.

scholarly journals Thermoelectric current in topological insulator nanowires with impurities

2018 ◽  
Vol 9 ◽  
pp. 1156-1161 ◽  
Author(s):  
Sigurdur I Erlingsson ◽  
Jens H Bardarson ◽  
Andrei Manolescu
Keyword(s):  
Magnetic Field ◽  
Topological Insulator ◽  
Temperature Difference ◽  
Impurity Concentration ◽  
Magnetic Impurities ◽  
Perpendicular Magnetic Field ◽  
Sign Reversal ◽  
Charge Current ◽  
Zero Voltage ◽  
The Magnetic Field

In this paper we consider charge current generated by maintaining a temperature difference over a nanowire at zero voltage bias. For topological insulator nanowires in a perpendicular magnetic field the current can change sign as the temperature of one end is increased. Here we study how this thermoelectric current sign reversal depends on the magnetic field and how impurities affect the size of the thermoelectric current. We consider both scalar and magnetic impurities and show that their influence on the current are quite similar, although the magnetic impurities seem to be more effective in reducing the effect. For moderate impurity concentration the sign reversal persists.

Magnetic Field Induced Sign Reversal of the Anomalous Hall Effect in a Pyrochlore FerromagnetNd2Mo2O7: Evidence for a Spin Chirality Mechanism

2003 ◽  
Vol 90 (25) ◽  
Author(s):  
Y. Taguchi ◽  
T. Sasaki ◽  
S. Awaji ◽  
Y. Iwasa ◽  
T. Tayama ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Hall Effect ◽  
Anomalous Hall Effect ◽  
Sign Reversal

scholarly journals Ultrasmall magnetic field-effect and sign reversal in transistors based on donor/acceptor systems

2017 ◽  
Vol 8 ◽  
pp. 1104-1114 ◽  
Author(s):  
Thomas Reichert ◽  
Tobat P I Saragi
Keyword(s):  
Magnetic Field ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Magnetic Field Effect ◽  
Charge Carrier Density ◽  
Magnetic Field Effects ◽  
Organic Field Effect Transistors ◽  
Transport Channel ◽  
Sign Reversal ◽  
Donor Acceptor

We present magnetoresistive organic field-effect transistors featuring ultrasmall magnetic field-effects as well as a sign reversal. The employed material systems are coevaporated thin films with different compositions consisting of the electron donor 2,2',7,7'-tetrakis-(N,N-di-p-methylphenylamino)-9,9'-spirobifluorene (Spiro-TTB) and the electron acceptor 1,4,5,8,9,12-hexaazatriphenylene hexacarbonitrile (HAT-CN). Intermolecular charge transfer between Spiro-TTB and HAT-CN results in a high intrinsic charge carrier density in the coevaporated films. This enhances the probability of bipolaron formation, which is the process responsible for magnetoresistance effects in our system. Thereby even ultrasmall magnetic fields as low as 0.7 mT can influence the resistance of the charge transport channel. Moreover, the magnetoresistance is drastically influenced by the drain voltage, resulting in a sign reversal. An average B 0 value of ≈2.1 mT is obtained for all mixing compositions, indicating that only one specific quasiparticle is responsible for the magnetoresistance effects. All magnetoresistance effects can be thoroughly clarified within the framework of the bipolaron model.

scholarly journals Sign reversal in magnetic field amplification by relativistic laser-driven microtube implosions

2020 ◽  
Vol 117 (24) ◽  
pp. 244101
Author(s):  
K. Weichman ◽  
M. Murakami ◽  
A. P. L. Robinson ◽  
A. V. Arefiev
Keyword(s):  
Magnetic Field ◽  
Sign Reversal ◽  
Field Amplification

Transport Properties of Superconductors in the Mixed State

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3102-3105 ◽  
Author(s):  
Jan Koláček ◽  
Petr Vašek
Keyword(s):  
Magnetic Field ◽  
Magnetic Field Dependence ◽  
Equations Of Motion ◽  
Charge Carriers ◽  
Hall Voltage ◽  
Sign Reversal ◽  
New Formula ◽  
The Magnetic Field ◽  
Properties Of Superconductors ◽  
State Charge

The Hall voltage sign reversal is consistently explained by the model in which vortices with the superconducting and normal state charge carriers are regarded as three independent subsystems mutually connected by interactions. The equations of motion for these three subsystems are solved simultaneously and a new formula for the Hall resistivity is obtained. It is shown that by this model it is possible to explain qualitatively experimental data. Despite of the fact that the pinning forces have not been taken into account the formula qualitatively explains not only the double Hall voltage sign reversal observed in Bi and Tl based superconductors below the critical temperature but also the magnetic field dependence of the Hall conductivity.

scholarly journals High magnetic field induced charge density waves and sign reversal of the Hall coefficient in graphite

2010 ◽  
Vol 22 (43) ◽  
pp. 436004 ◽  
Author(s):  
Amit Kumar ◽  
Jean-Marie Poumirol ◽  
Walter Escoffier ◽  
Michel Goiran ◽  
Bertrand Raquet ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Charge Density ◽  
High Magnetic Field ◽  
Hall Coefficient ◽  
Charge Density Waves ◽  
Density Waves ◽  
Sign Reversal ◽  
Induced Charge Density ◽  
Induced Charge

MAGNETIC DEPENDENCE OF HALL SIGN REVERSAL FOR Gd1-xPrxBa2Cu3O7-δ IN A VORTEX STATE

2002 ◽  
Vol 16 (22) ◽  
pp. 853-860 ◽  
Author(s):  
V. DAADMEHR ◽  
H. NAGHSHARA ◽  
M. AKHAVAN
Keyword(s):  
Magnetic Field ◽  
High Temperature Superconductors ◽  
Vortex State ◽  
Complex Nature ◽  
Field Region ◽  
Sign Reversal ◽  
Hall Resistivity ◽  
Sign Change ◽  
Magnetic Field Region ◽  
The Magnetic Field

We have investigated the sign reversal of Hall effect in high-temperature superconductors in the vortex state as a function of temperature for several samples of Gd 1-x Pr x Ba 2 Cu 3 O 7-δ with 0.2 ≥ x ≥ 0 in a magnetic field of 0–2 T. Multiple sign reversals of Hall resistivity have been observed in under-doped and partially over-doped samples. The Gd 1-x Pr x Ba 2 Cu 3 O 7-δ sample with x = 0.1 shows double sign change in Hall resistivity with variation of magnetic field, and a single sign reversal with variation of temperature. While for the x = 0.15 and x = 0.2 samples, no sign reversal is observed, for the x < 0.1 sample, one sign change of Hall resistivity with temperature over the magnetic field region is observed. The tan (θ H ) also shows a similar double sign reversal of Hall resistivity. This can be related to the particle-hole asymmetry and the complex nature of the Fermi surface.

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