Dilute Potts chain in a magnetic field

1984 ◽  
Vol 62 (1) ◽  
pp. 69-72 ◽  
Author(s):  
C. M. Chaves ◽  
Rosane Riera

The Potts lattice gas in the presence of a uniform magnetic field is solved exactly in one dimension. For negative values of the exchange parameter, the magnetization curve exhibits two or three steps, depending on the concentration of vacancies. These steps arise as a result of the competition between the exchange interaction and the magnetic field, and are associated with different structural distributions of vacancies and the magnetic ordering of one or both sublattices.

MRS Advances ◽  
2019 ◽  
Vol 4 (36) ◽  
pp. 1989-1999 ◽  
Author(s):  
Valery Sobol ◽  
Barys Korzun ◽  
Olga Mazurenko ◽  
Temirkhan Bizhigitov ◽  
Sabit Tomaev

ABSTRACTBismuth ferrite (BiFeO3) and La-, Nd- and Gd-substituted bismuth ferrite of the Bi1-xLaxFeO3, Bi1-xNdxFeO3, and Bi1-xGdxFeO3 types with the atomic part of the substitution element x equal up to 0.20 were synthesized by the solid-state reaction method using powders of oxides Bi2O3, Fe2O3, and La2O3, or Nd2O3, or Gd2O3 of pure grade quality and investigated using X-ray diffraction analysis. The magnetization was measured in the magnetic field up to 6.5⋅106 A/m at 5 and 300 K. It was found that the total substitution up to 0.20 atomic part of Bi by La, Nd, and Gd leads to the paramagnetic behavior of the doped bismuth ferrite at low temperatures in a wide range of magnetic field. Strong nonlinear dependence of magnetization on the magnetic field was detected and a ferromagnetic-like dependence of magnetization was observed for small magnetic fields. This can be explained by the exchange interaction between doping magnetic ions, as well as by the exchange interaction of these ions with ions of iron. The enhancement of magnetic properties with the increase of the content of the substitution is monotone and is more pronounced for the Bi1-xGdxFeO3 ceramics.


The stability of viscous flow between two coaxial cylinders maintained by a constant transverse pressure gradient is considered when the fluid is an electrical conductor and a uniform magnetic field is impressed in the axial direction. The problem is solved and the dependence of the critical number for the onset of instability on the strength of the magnetic field and the coefficient of electrical conductivity of the fluid is determined.


Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 467
Author(s):  
Fayçal Hammad ◽  
Alexandre Landry ◽  
Parvaneh Sadeghi

The relativistic wave equation for spin-1/2 particles in the interior Schwarzschild solution in the presence of a uniform magnetic field is obtained. The fully relativistic regime is considered, and the energy levels occupied by the particles are derived as functions of the magnetic field, the radius of the massive sphere and the total mass of the latter. As no assumption is made on the relative strengths of the particles’ interaction with the gravitational and magnetic fields, the relevance of our results to the physics of the interior of neutron stars, where both the gravitational and the magnetic fields are very intense, is discussed.


2018 ◽  
Vol 185 ◽  
pp. 09006
Author(s):  
Alexander Tyatyushkin

Small steady-state deformational oscillations of a drop of magnetic liquid in a nonstationary uniform magnetic field are theoretically investigated. The drop is suspended in another magnetic liquid immiscible with the former. The Reynolds number is so small that the inertia can be neglected. The variation of the magnetic field is so slow that the quasi-stationary approximation for the magnetic field and the quasi-steady approximation for the flow may be used.


Author(s):  
Rajesh Nimmagadda ◽  
Durga Prakash Matta ◽  
Rony Reuven ◽  
Lazarus Godson Asirvatham ◽  
Somchai Wongwises ◽  
...  

Abstract A 2D numerical investigation has been carried out to obtain the heat transfer performance of hybrid (Al2O3 + Ag) nanofluid in a lid driven cavity over solid block under the influence of uniform as well as non-uniform magnetic field. The geometrical domain consists of a cavity containing nanofluid that is driven by means of lid moving in one direction. This circulating nanofluid will extract enormous amount of heat from the solid block underneath the cavity resulting in conjugate heat transfer. A homogenous solver based on the finite volume method with conjugate heat transfer was developed and adopted in the existing study. The heat efficient hybrid nanofluid (HyNF) pair (2.4 vol.% Ag + 0.6 vol.% Al2O3) obtained by Nimmagadda and Venkatasubbaiah [1] is used in the present investigation. Moreover, efficient non-uniform sinusoidal magnetic field identified by Nimmagadda et al. [2] is also implemented and compared with uniform magnetic field. Furthermore, the magnetic field is applied over the geometrical domain along the two axial directions separately and the effective heat transfer performance is obtained. The significant impact of extensive parameters like Reynolds number, nanoparticle type, nanoparticle concentration, magnetic field type, magnetic field location and the strength of the magnetic field on heat transfer performance are systematically analyzed and presented.


2013 ◽  
Vol 770 ◽  
pp. 374-377
Author(s):  
Apichart Sankote ◽  
Kheamrutai Thamaphat ◽  
Supanee Limsuwan

In this work, a method to measuring the magnitude of a uniform magnetic field in space using current balance was described. A simple experimental set was designed and constructed using low-cost materials. This constructed current balance consists of copper sheet, weight pan, and acrylic sheet. A copper sheet was cut into a U-shape and attached at the end of acrylic balance arm. A weight pan was hanged in the opposite side of the balance arm with high sensitivity to a small torque. The horizontal segment of the U-shaped copper sheet, which the length l was 3 cm, was located inside the influence of an uniform magnetic field produced by two parallel bar magnets with opposite poles facing each other. The magnetic field direction was perpendicular to the horizontal segment. When a current was supplied to the copper sheet, the magnetic force acting on a horizontal segment of length l carrying a current I in a magnetic field B was given by. In the experiment, the current was varied from 0 1 A. For each value of applied current, the magnetic force on a thin straight sheet of length l was measured by adding masses to the pan until the balance arm moved to the equilibrium between opposing gravitational and magnetic forces. The results showed that the magnetic force increased linearly with increasing applied current. By plotting a linear graph of magnetic force versus applied current, the magnetic field B can be calculated from . The calculated and actual values of B were 100.32 and 100.13 mT, respectively. This constructed current balance is an excellent tool for high school and undergraduate fundamental physics courses. Students will be excited when they see the balance arm rising or going down due to magnitude and direction of current flowing in a conductor wire.


1986 ◽  
Vol 89 ◽  
Author(s):  
M. Gorska ◽  
J. R. Anderson ◽  
Z. Golacki

AbstractThe magnetization and magnetic susceptibility of Bridgman-grown Pb1-xGdxTe have been measured over a temperature range from 2 to 300 K and in magnetic fields from 0.01 to 50 κOe. The x-values of the crystals ranged from 0.03 to 0.07. The magnetic susceptibility followed a Curie-Weiss behavior, χ = C/(T + θ), with positive θ implying an antiferromagnetic exchange interaction between Gd ions. The magnetic field dependence of the magnetization was fitted to a modified Brillouin function with parameter values that agreed fairly well with those from Curie-Weiss plots. The magnitude of θ was comparable to the value found for Pb1-xMnxTe for similar x values; but since the ion spin is bigger for Gd this suggests that the exchange interaction in Gd-doped PbTe is roughly half the value in Mn-doped PbTe.


1963 ◽  
Vol 18 (8-9) ◽  
pp. 889-895
Author(s):  
F. Schwirzke

The radial density distribution for a plasma in a uniform magnetic field was studied in dependence of pressure and distance of the conducting end plates. It was possible to confirm experimentally the dependence of the radial distribution of the finite length in direction of the field lines. The influence of the magnetic field, of the pressure, and of the length of the plasma column on the radial density profile is, in different gases, qualitatively in accordance with the “short-circuiting” theory of A. SIMON.


1995 ◽  
Vol 384 ◽  
Author(s):  
V.V. Ustinov ◽  
V.I. Minin ◽  
L.N. Romashev ◽  
A.B. Semerikov ◽  
A.R. Del

ABSTRACTWe study the magnetoresistance of [Fe/Cr]30/MgO superlattices grown by molecular beam epitaxy at a various magnetic field directions. The theory of the orientation dependence of the effect is developed. It is shown that the magnetic field strength dependence of magnetoresistance can be calculated for arbitrary orientation of magnetic field if this dependence is known for in-plane and perpendicular-to-plane magnetic fields. It is noted that the magnetization curve can be obtained by making use of the results of the magnetoresistance measurements.


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