Evidence of Magnetoelectric Coupling in Pb(Fe0.5Nb0.5)O3 Ceramics Through Impedance Spectroscopy and Electromechanical Resonance Measurements

2009 ◽  
Vol 1161 ◽  
Author(s):  
Oscar Raymond ◽  
Reinaldo Font ◽  
Nelson S. Almodovar ◽  
Jorge J. Portelles ◽  
Jesús M Siqueiros
Keyword(s):  
Magnetic Field ◽  
Impedance Spectroscopy ◽  
Applied Magnetic Field ◽  
Electromechanical Coupling ◽  
Complex Dielectric Constant ◽  
Antiferromagnetic Order ◽  
Small Signal ◽  
Large Signal ◽  
Signal Response ◽  
Electromechanical Resonance

AbstractMultifunctional materials such as the single phase compound Pb(Fe0.5Nb0.5)O3 (PFN), where ferroelectric and antiferromagnetic order coexist, are very promising and have great interest from the academic and technological points of view. In this work, coupling of the ferroelectric and magnetic ordering has been observed. For this study, a combination of the small signal response using the impedance spectroscopy technique and the electromechanical resonance method with the large signal response through standard ferroelectric measurement, has been used with and without an applied magnetic field. The measurements to determine the electrical properties of the ceramic were performed as functions of the bias and poling electric fields. A simultaneous analysis of the complex dielectric constant , impedance , electric modulus , and the electromechanical coupling factors is presented. The results are correlated with a previous study of structural, morphological, small signal dielectric frequency-temperature response, and the ferroelectric hysteretic, magnetic and magnetodielectric behaviors. The observed shifts of the resonance and antiresonance frequency values can be associated with change of the domain size favored by the readjustment of the oxygen octahedron when the magnetic field is applied.From P-E hysteresis loops obtained without and with an external applied magnetic field a maximum value of dc magnetoelectric coefficient αME = 4 kV/cm T (400 mV/cm Oe) was obtained.

scholarly journals Antiferromagnetic order induced by an applied magnetic field in a high-temperature superconductor

Nature ◽  
2002 ◽  
Vol 415 (6869) ◽  
pp. 299-302 ◽  
Author(s):  
B. Lake ◽  
H. M. Rønnow ◽  
N. B. Christensen ◽  
G. Aeppli ◽  
K. Lefmann ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
Applied Magnetic Field ◽  
High Temperature Superconductor ◽  
Antiferromagnetic Order

MESFET large-signal model based on small-signal measurements for time-domain CAD

1988 ◽  
Vol 24 (15) ◽  
pp. 973 ◽  
Author(s):  
A. Ouslimani ◽  
G. Vernet ◽  
J.C. Henaux ◽  
P. Crozat ◽  
R. Adde
Keyword(s):  
Time Domain ◽  
Small Signal ◽  
Large Signal ◽  
Signal Model ◽  
Model Based

scholarly journals Generation of Reverse Meniscus Flow by Applying An Electromagnetic Brake

2021 ◽  
Author(s):  
Alexander Vakhrushev ◽  
Abdellah Kharicha ◽  
Ebrahim Karimi-Sibaki ◽  
Menghuai Wu ◽  
Andreas Ludwig ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Lorentz Force ◽  
Applied Magnetic Field ◽  
Numerical Study ◽  
Flow Direction ◽  
Experimental Studies ◽  
Submerged Entry Nozzle ◽  
Mean Flow ◽  
Slab Caster ◽  
The Mean

AbstractA numerical study is presented that deals with the flow in the mold of a continuous slab caster under the influence of a DC magnetic field (electromagnetic brakes (EMBrs)). The arrangement and geometry investigated here is based on a series of previous experimental studies carried out at the mini-LIMMCAST facility at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The magnetic field models a ruler-type EMBr and is installed in the region of the ports of the submerged entry nozzle (SEN). The current article considers magnet field strengths up to 441 mT, corresponding to a Hartmann number of about 600, and takes the electrical conductivity of the solidified shell into account. The numerical model of the turbulent flow under the applied magnetic field is implemented using the open-source CFD package OpenFOAM®. Our numerical results reveal that a growing magnitude of the applied magnetic field may cause a reversal of the flow direction at the meniscus surface, which is related the formation of a “multiroll” flow pattern in the mold. This phenomenon can be explained as a classical magnetohydrodynamics (MHD) effect: (1) the closure of the induced electric current results not primarily in a braking Lorentz force inside the jet but in an acceleration in regions of previously weak velocities, which initiates the formation of an opposite vortex (OV) close to the mean jet; (2) this vortex develops in size at the expense of the main vortex until it reaches the meniscus surface, where it becomes clearly visible. We also show that an acceleration of the meniscus flow must be expected when the applied magnetic field is smaller than a critical value. This acceleration is due to the transfer of kinetic energy from smaller turbulent structures into the mean flow. A further increase in the EMBr intensity leads to the expected damping of the mean flow and, consequently, to a reduction in the size of the upper roll. These investigations show that the Lorentz force cannot be reduced to a simple damping effect; depending on the field strength, its action is found to be topologically complex.

scholarly journals Stability of nonaxisymmetric ferrofluid flow in rotating cylinders with magnetic field

2005 ◽  
Vol 2005 (23) ◽  
pp. 3727-3737 ◽  
Author(s):  
Jitender Singh ◽  
Renu Bajaj
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Critical Value ◽  
Annular Space ◽  
Rotating Cylinders ◽  
The Stability

Effect of an axially applied magnetic field on the stability of a ferrofluid flow in an annular space between two coaxially rotating cylinders with nonaxisymmetric disturbances has been investigated numerically. The critical value of the ratioΩ∗of angular speeds of the two cylinders, at the onset of the first nonaxisymmetric mode of disturbance, has been observed to be affected by the applied magnetic field.

scholarly journals Phase boundary dynamics of bubble flow in a thick liquid metal layer under an applied magnetic field

2020 ◽  
Vol 5 (6) ◽  
Author(s):  
Mihails Birjukovs ◽  
Valters Dzelme ◽  
Andris Jakovics ◽  
Knud Thomsen ◽  
Pavel Trtik
Keyword(s):  
Magnetic Field ◽  
Liquid Metal ◽  
Phase Boundary ◽  
Applied Magnetic Field ◽  
Metal Layer ◽  
Bubble Flow ◽  
Boundary Dynamics
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