Calculation of the H-T phase diagram, magnetization and susceptibility in layered structures

Yurtseven, Hasan Hamit
Emre, B.
Acet, M.
The magnetic Field-temperature (H-T) phase diagram is calculated using the mean held theory by expanding the free energy in terms of the uniform and staggered magnetization for the ferromagnetic-antiferromagnetic transitions in the La0.6Nd0.4Mn2Si2 multilayer structures. Using our experimental measurements, analysis of the magnetization as a function of the magnetic held at constant temperatures from 45 K to 250 K is performed by a power-law formula close to the ferromagnetic-antiferromagnetic transitions. Also, by obtaining the magnetic field dependence of the isothermal susceptibility chi(T) from the M-H curves, chi(T) vs. H-H-c, is analyzed (H-c is the critical magnetic field) using a powerlaw formula for the antiferromagnetic-ferromagnetic (AF-FM) transitions in La0.6Nd0.4Mn2Si2. It is found that a discontinuous (first order) transition which occurs at the lowest (45 K) and the highest (250 K) temperatures, changes to a continuous one at a constant temperature at around 100 K as the magnetic Field carries the systems from the antiferromagnetic to the ferromagnetic phase. Values of the critical exponents associated with this transition are deduced and they are compared with the predictions of some theoretical models.


Calculation of a phase diagram for the ice II-V-VItransitions
Tari, O; Yurtseven, Hasan Hamit; Salihoglu, S (2000-12-01)
In this study we calculate the P - T phase diagram of ice II - V - VI using a mean field model. Our calculated phase line equations are fitted to the experimental data from the literature. There is a very good agreement between our calculated and experimentally observed P - T phase diagram of ice II - V - VI.
Calculation of the P-T phase diagram of nitrogen using a mean field model
Enginer, Y.; Algul, G.; Yurtseven, Hasan Hamit (2017-12-20)
The P-T phase diagram is calculated at low and moderate pressures by obtaining the phase line equations for the transitions considered in nitrogen using the Landau phenomenological model. For some transitions, a quadratic coupling between the order parameters is taken into account in the expansion of free energies in terms of the order parameters. A quadratic function in T and P is fitted to the experimental P-T data from the literature and the fitted parameters are determined.
Calculation of a generalised smectic–hexatic phase diagram in liquid crystals
Yurtseven, Hasan Hamit (Informa UK Limited, 2012-5)
This study gives a generalised smectic-hexatic phase diagram calculated by the Landau mean field theory. Our calculated phase line equations are fitted to the experimental phase lines, which represent first-order transition for the liquid crystals studied here. The temperature-and concentration-dependent phase lines calculated in this study describe the observed T-X phase diagram for the smectic-hexatic transitions. This indicates that the method of calculating the phase line equations from the mean field t...
Numerical simulation of thermal convection under the influence of a magnetic field by using solenoidal bases
Yarımpabuç, Durmuş; Tarman, Işık Hakan; Department of Engineering Sciences (2011)
The effect of an imposed magnetic field on the thermal convection between rigid plates heated from below under the influence of gravity is numerically simulated in a computational domain with periodic horizontal extent. The numerical technique is based on solenoidal basis functions satisfying the boundary conditions for both velocity and induced magnetic field. The expansion bases for the thermal field are also constructed to satisfy the boundary conditions. The governing partial differential equations are ...
Calculation of the soft mode frequency for the alpha beta transition in quartz
Yurtseven, Hasan Hamit (null; 2015-09-18)
The Raman frequencies of the lattice modes (147 cm-1 and 207 cm-1 are analyzed for the α-β transition in quartz according to a power-law formula with the critical exponent by using the experimental data. The temperature dependence of the Raman frequency is associated with the order parameter (polarization P) for this transition in the quartz crystal. The damping constant of the lattice modes studied here is calculated using the Raman frequencies at various temperatures for the α-β transition in quartz (Tc =...
Citation Formats
H. H. Yurtseven, B. Emre, and M. Acet, “Calculation of the H-T phase diagram, magnetization and susceptibility in layered structures,” JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, pp. 544–550, 2015, Accessed: 00, 2020. [Online]. Available: