Rotation and deformation of the optical indicatrix of hematite during the magnetic field‐induced phase transition

1978 ◽  
Vol 49 (3) ◽  
pp. 2192-2194
Author(s):  
C. Leycuras ◽  
E. G. Rudachevskii ◽  
H. Le Gall ◽  
V. S. Merkoulov
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Optical Indicatrix ◽  
The Magnetic Field

SPECTRAL PROPERTIES AND SYMMETRIES OF DOUBLE COVERINGS OF GRAPHS WITH APPLICATIONS TO SUPERCONDUCTIVITY

2005 ◽  
Vol 15 (02) ◽  
pp. 301-324
Author(s):  
JACOB RUBINSTEIN ◽  
MICHELLE SCHATZMAN
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Phase Transitions ◽  
Ground State ◽  
Spectral Properties ◽  
Embedded Graph ◽  
Symmetry Constraints ◽  
The Laplace Operator ◽  
The Magnetic Field ◽  
Double Coverings

Let M be a planar embedded graph, and let [Formula: see text] be its double covering. We count the multiplicity of the ground states of the Laplace operator on [Formula: see text] under certain symmetry constraints. The examples of interest for us are ladder-like graphs made out of n, identical rectangles. We find that in the case of an odd n, the multiplicity of the ground state is 2, and if n, is even, the ground state is simple. This result gives an answer to a conjecture by Parks on the type of phase transitions that can occur in a superconducting ladder: Parks conjectured that in the case when the magnetic field is one half fluxoid per rectangle, the phase transition would be continuous in the case of a ladder made out of two rectangles. Our result indeed implies Parks conjecture and generalizes it to any even ladder. The mathematics of this paper is a mixture of topology, symmetry arguments and comparison theorem between the eigenvalues of Laplace operators on graphs with well chosen boundary conditions.

scholarly journals Precessing Ball Solitons in Kinetics of a Spin-Flop Phase Transition

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
V. V. Nietz
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Uniaxial Anisotropy ◽  
Precession Frequency ◽  
Initial Condition ◽  
Configuration Energy ◽  
Wide Range ◽  
Kinetics Of ◽  
New Phase ◽  
The Magnetic Field

The fundamentals of precessing ball solitons (PBS), arising as a result of the energy fluctuations during spin-flop phase transition induced by a magnetic field in antiferromagnets with uniaxial anisotropy, are presented. The PBS conditions exist within a wide range of amplitudes and energies, including negative energies relative to an initial condition. For each value of the magnetic field, there exists a precession frequency for which a curve of PBS energy passes through a zero value (in bifurcation point), and hence, in the vicinity of this point the PBS originate with the highest probability. The characteristics of PBS, including the time dependences of configuration, energy, and precession frequency, are considered. As a result of dissipation, the PBS transform into the macroscopic domains of a new phase.

Pressure Dependence of the de Haas – van Alphen Effect in Ytterbium

1974 ◽  
Vol 52 (17) ◽  
pp. 1622-1627 ◽  
Author(s):  
A. J. Slavin ◽  
W. R. Datars
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Phase Transformation ◽  
Pressure Dependence ◽  
Experimental Error ◽  
Solid Helium ◽  
Field Direction ◽  
Magnetic Field Direction ◽  
Pressure Medium ◽  
The Magnetic Field

The de Haas–van Alphen effect and the h.c.p.–f.c.c. phase transformation of ytterbium were studied with the magnetic field along the [0001] direction in the h.c.p. phase, using pressures up to 4 kbar. Solid helium was used as the pressure medium. The pressure dependence of the three dHvA frequencies in the h.c.p. phase for the [0001] magnetic field direction was linear within experimental error with dF/dP = −1.2 ± 0.2 T/kbar for F(P = 0) of 35.4 T, dF/dP = 0.30 ± 0.03 T/kbar for F(P = 0) of 142.5 T, and dF/dP = −0.78 ± 0.10 T/kbar for F(P = 0) of 156.4 T. The dHvA amplitude in the h.c.p. phase was independent of pressure up to the phase transition and no dHvA effect was observed in the f.c.c. phase. The pressure of the phase transformation at 1.2 K was determined to be 2.15 ± 0.05 kbar.

scholarly journals EFFECT OF MUONS ON THE PHASE TRANSITION IN MAGNETIZED PROTO-NEUTRON STAR MATTER

2002 ◽  
Vol 11 (09) ◽  
pp. 1505-1513
Author(s):  
ASHA GUPTA ◽  
V. K. GUPTA ◽  
S. SINGH ◽  
J. D. ANAND
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Neutron Star ◽  
Transition Density ◽  
Nuclear Density ◽  
Muon Neutrinos ◽  
Neutron Star Matter ◽  
Chemical Potentials ◽  
The Magnetic Field ◽  
Proto Neutron Star

We study the effect of the inclusion of muons and the muon neutrinos on the phase transition from nuclear to quark matter in a magnetized proto-neutron star and compare our results with those obtained by us without the muons. We find that the inclusion of muons changes slightly the nuclear density at which transition occurs. However the dependence of this transition density on various chemical potentials, temperature and the magnetic field remains quantitatively the same.

scholarly journals Намагниченность и гигантское магнетосопротивление поликристаллов TbSb при низких температурах

2019 ◽  
Vol 61 (8) ◽  
pp. 1470
Author(s):  
М.П. Волков ◽  
Н.Н. Степанов
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Antiferromagnetic Phase ◽  
Positive Magnetoresistance ◽  
The Magnetic Field

On the terbium antimonide TbSb polycrystals, the dependences of the magnetization M and the resistance R on the temperature T in the range of 2 ÷ 300 K and on the magnetic field H up to H = 14 T have been studied. On the dependences M (H) at each temperature, a feature (kink) was observed associated with the metamagnetic phase transition. Giant positive magnetoresistance of TbSb in the region of the antiferromagnetic phase has been found.

scholarly journals Numerical Simulation of the Phase Transition Control in a Cylindrical Sample Made of Ferromagnetic Shape Memory Alloy

Computation ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 38
Author(s):  
Anatoli A. Rogovoy ◽  
Olga S. Stolbova
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Shape Memory ◽  
Outer Surface ◽  
Original Position ◽  
Cubic Phase ◽  
Temperature Phase ◽  
Martensitic State ◽  
Ferromagnetic Shape Memory ◽  
The Magnetic Field

The paper considers ferromagnetic alloys, which exhibit the shape memory effect during phase transition from the high-temperature cubic phase (austenite) to the low-temperature tetragonal phase (martensite) in the ferromagnetic state. In these alloys, significant macroscopic strains are generated during the direct temperature phase transition from the austenitic to the martensitic state, provided that the process proceeds under the action of the applied mechanical stresses. The critical phase transition temperatures in such alloys depend not only on the stress fields, but also on the magnetic field. By changing the magnetic field, it is possible to control the process of phase transition. In this work, within the framework of the finite deformation theory, we develop a model that allows us to describe the process of the control of the direct (austenite-martensite) and reverse (martensite-austenite) phase transitions in ferromagnetic shape memory polycrystalline materials under the action of external force, thermal, and magnetic fields with the aid of the magnetic field. In view of the fact that the magnetic field affects the material deformation, which, in turn, changes the magnetic field, we formulated and solved a coupled boundary value problem. As an example, we considered the problem of a shift of the outer surface of a long hollow cylinder made of ferromagnetic alloy. The numerical implementation of the problem was based on the finite element method using the step-by-step loading procedure. Complete recovery of the strains accumulated during the direct phase transition and reverting of the axially-displaced outer surface of the cylinder to its original position occurred both on heating of the sample to the temperatures of the reverse phase transition and at a constant temperature, when the magnetic field previously applied in the martensitic state was removed.

Magnetic Properties and Phase Diagram of Quasi-two-dimensional Na2Co2TeO6 Single Crystal Under High Magnetic Field

2021 ◽  
Author(s):  
Guiling Xiao ◽  
Zhengcai Xia ◽  
Yujie Song ◽  
Lixia Xiao
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Phase Diagram ◽  
Magnetic Phase ◽  
Magnetic Coupling ◽  
Experimental Results ◽  
Antiferromagnetic Coupling ◽  
Magnetic Field Direction ◽  
Antiferromagnetic Ordering ◽  
The Magnetic Field

Abstract We investigated the magnetic characteristics of Na2Co2TeO6 at different temperatures and magnetic field. The experimental results indicated that the magnetic field can disturb the antiferromagnetic interaction and lead to the disorder. Magnetization curves measured with different angles θ (θ is between the magnetic field direction and c axis) express the magnetocrystalline anisotropy in this system. when the angle θ=0 (magnetic field parallel to c axis), two continuous magnetic phase transitions at critical temperature TN1 and TN3 were observed. As θ changes, TN1 is almost independent on θ, indicating the magnetic ordering at TN1 was a spontaneous behavior with a robust AFM characteristic. On the other hand, as θ increases from 0 to 180, TN3 presents extreme value at θ=90 (magnetic field perpendicular to c axis). It indicates that TN3 were sensitive to temperature and magnetic fields. At some angles closing to ab plane, an additional phase transition was observed at TN2. This phase transition at TN2 may mainly result from the long range antiferromagnetic ordering within ab-plane. Furthermore, the magnetization measurement up to 50 T revealed the strong antiferromagnetic coupling in the system, and in which the magnetic coupling within the honeycomb layers is strong and the magnetic coupling interaction between honeycomb layers is weaker. Based on the experimental results, we have obtained the complete magnetic phase diagram.

Phase Transition in 2D Anisotropic Ising Model with Next-Nearest Neighbor Interactions in a Magnetic Field

SPIN ◽  
2018 ◽  
Vol 08 (03) ◽  
pp. 1850010
Author(s):  
D. Farsal ◽  
M. Badia ◽  
M. Bennai
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Phase Diagram ◽  
Monte Carlo ◽  
Magnetic Susceptibility ◽  
Critical Temperature ◽  
Ising Model ◽  
Nearest Neighbor ◽  
Two Dimensional ◽  
The Magnetic Field

The critical behavior at the phase transition of the ferromagnetic two-dimensional anisotropic Ising model with next-nearest neighbor (NNN) couplings in the presence of the field is determined using mainly Monte Carlo (MC) method. This method is used to investigate the phase diagram of the model and to verify the existence of a divergence at null temperature which often appears in two-dimensional systems. We analyze also the influence of the report of the NNN interactions [Formula: see text] and the magnetic field [Formula: see text] on the critical temperature of the system, and we show that the critical temperature depends on the magnetic field for positive values of the interaction. Finally, we have investigated other thermodynamical qualities such as the magnetic susceptibility [Formula: see text]. It has been shown that their thermal behavior depends qualitatively and quantitatively on the strength of NNN interactions and the magnetic field.

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