Phase transition of BiMnO3 multiferroic thin film by Landau–Ginzburg theory

2016 ◽  
Vol 30 (14) ◽  
pp. 1650082 ◽  
Author(s):  
Ahmad Musleh Alrub ◽  
Lye-Hock Ong ◽  
K.-H. Chew ◽  
J. M. Khoshman ◽  
Ghadeer N. Al Shabaan ◽  
...  
Keyword(s):  
Thin Film ◽  
Phase Transition ◽  
Free Energy ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Thermodynamic Properties ◽  
Magnetic Transition ◽  
Order Parameters ◽  
Energy Term ◽  
Magnetic Transition Temperature

Magnetoelectric (ME) multiferroic bismuth manganite (BiMnO[Formula: see text] has ferroelectric (FE) and ferromagnetic order parameters that coupled biquadratically. Landau free energy expression in these order parameters is proposed to investigate the phase transition and thermodynamic properties of a BiMnO3 film. The surface energy term is included in the free energy. We find that the ME coupling enhances the magnetic transition temperature. The magnetization and polarization order parameters are both increased strongly below the new magnetic transition temperature. The curves for magnetization and polarization versus temperature show that the phase transition is second-order. The entropy, free energy, and specific heat of the BiMnO3 multiferroic are calculated. Thickness-driven phase transitions for magnetization and polarization of BiMnO3 thin film are clearly indicated.

Effect of Co and Mg doping at Cu site on structural, magnetic and dielectric properties of α-Cu2V2O7

2021 ◽  
Author(s):  
Abja Keshar Kar ◽  
Bidisa Chattopadhyay ◽  
Ratnadwip Singha ◽  
Abhisikta Barman ◽  
Md Azaharuddin Ahmed ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Landau Theory ◽  
Critical Concentration ◽  
Magnetic Transition ◽  
Magnetic Phase Diagram ◽  
Ferromagnetic Behavior ◽  
Magnetic Transition Temperature ◽  
Mg Doping ◽  
Β Phase

Abstract We have studied the effect of doping of both magnetic (Co) and nonmagnetic (Mg) ions at the Cu site on phase transition in polycrystalline α-Cu2V2O7 through structural, magnetic, and electrical measurements. x-ray diffraction reveals that Mg doping triggers an onset of α- to β-phase structural transition in Cu2−xMgxV2O7 above a critical Mg concentration xc=0.15, and both the phases coexist up to x=0.25. Cu2V2O7 possesses a non-centrosymmetric(NCSM) crystal structure and antiferromagnetic (AFM) ordering along with a non-collinear spin structure in the α phase, originated from the microscopic Dzyaloshinskii-Moriya(DM) interaction between the neighboring Cu spins. Accordingly, a weak ferromagnetic behavior has been observed up to x=0.25. However, beyond this concentration, Cu2−xMgxV2O7 exhibits complex magnetic properties. A clear dielectric anomaly is observed in α-Cu2−xMgxV2O7 around the magnetic transition temperature, which loses its prominence with the increase in Mg doping. The analysis of experimental data shows that the magnetoelectric coupling is nonlinear, which is in agreement with the Landau theory of continuous phase transitions. Co doping, on the other hand, initiates a sharp α to β phase transition around the same critical concentration xc=0.15 in Cu2−xCoxV2O7 but the ferromagnetic behavior is very weak and can be detected only up to x=0.10. We have drawn the magnetic phase diagram which indicates that the rate of suppression in transition temperature is the same for both types of doping, magnetic (Co) and nonmagnetic (Zn/Mg).

Phase Transition and ThermodynamicProperties of OsN2 under High Pressure

2013 ◽  
Vol 401-403 ◽  
pp. 660-662
Author(s):  
Zhi Jian Fu ◽  
Li Jun Jia ◽  
Wei Long Quan
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Thermal Expansion ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Thermodynamic Properties ◽  
First Principles ◽  
Fluorite Structure ◽  
First Principles Calculations ◽  
Zero Temperature

The lattice parameters, phase transition, and thermodynamic properties of OsN2in pyrite and fluorite structure are investigated by first-principles calculations. The pressure and temperature induced phase transitions of OsN2from fluorite structure to pyrite structure have been obtained. It is found that the transition pressure of OsN2at zero temperature is 158.2 GPa, and there exists no transition temperature. In addition, the thermal expansion, the Debye temperature, and the Grüneisen parameter in diverse pressures and temperatures about these two structures have also been obtained. Key words: transition phase; thermodynamic properties; OsN2PACS numbers: 71.15.Mb, 64.70.Kb

Various types of holographic metal/superconductor phase transitions with dark matter sector

2016 ◽  
Vol 26 (06) ◽  
pp. 1750046
Author(s):  
Yan Peng ◽  
Tao Chen ◽  
Guohua Liu ◽  
Pengwei Ma
Keyword(s):  
Phase Transition ◽  
Black Hole ◽  
Dark Matter ◽  
Phase Transitions ◽  
Transition Temperature ◽  
De Sitter ◽  
Holographic Superconductor ◽  
Black Hole Background ◽  
Critical Phase ◽  
Matter Sector

We generalize the holographic superconductor model with dark matter sector by including the Stückelberg mechanism in the four-dimensional anti-de Sitter (AdS) black hole background away from the probe limit. We study effects of the dark matter sector on the [Formula: see text]-wave scalar condensation and find that the dark matter sector affects the critical phase transition temperature and also the order of phase transitions. At last, we conclude that the dark matter sector brings richer physics in this general metal/superconductor system.

INDUCED CHANGES OF THERMOTROPIC PROPERTIES OF PHASE TRANSITIONS BETWEEN SMECTIC A MESOPHASE AND ISOTROPIC LIQUID: EFFECT OF SURFACES

2006 ◽  
Vol 20 (14) ◽  
pp. 821-833 ◽  
Author(s):  
ARIF NESRULLAJEV ◽  
ŞENER OKTIK
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Transition ◽  
Phase Transitions ◽  
Isotropic Liquid ◽  
Smectic A ◽  
Phase Transition Temperatures ◽  
Smectic A Phase ◽  
Induced Changes ◽  
Thermotropic Properties

In this work, the effect of thin films on the thermotropic and thermo-optical properties and peculiarities of the phase transitions between the smectic A and isotropic liquid have been investigated. Peculiarities of the heterophase regions of the straight smectic A-isotropic liquid and reverse isotropic liquid-smectic A phase transitions have been studied. Change of morphologic properties of the heterophase regions, shift of the phase transition temperatures and the change of temperature widths of these heterophase regions under thin film influence have been observed.

Effect of A-site cation substitution on magnetic transition temperature of (LaCa) MnO3

1999 ◽  
Vol 42 (7) ◽  
pp. 758-762
Author(s):  
Kebin Li ◽  
Shouguo Wang ◽  
Rongsheng Cheng ◽  
Xijun Li ◽  
Denglu Hou ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Magnetic Transition ◽  
Cation Substitution ◽  
Magnetic Transition Temperature ◽  
A Site

Phase Transitions

2019 ◽  
pp. 205-222
Author(s):  
Robert H. Swendsen
Keyword(s):  
Phase Transition ◽  
Free Energy ◽  
Phase Transitions ◽  
Helmholtz Free Energy ◽  
Equations Of State ◽  
Van Der Waals ◽  
Ideal Gas ◽  
Phase Rule ◽  
Clapeyron Equation ◽  
Maxwell Construction

Phase transitions are introduced using the van der Waals gas as an example. The equations of state are derived from the Helmholtz free energy of the ideal gas. The behavior of this model is analyzed, and an instability leads to a liquid-gas phase transition. The Maxwell construction for the pressure at which a phase transition occurs is derived. The effect of phase transition on the Gibbs free energy and Helmholtz free energy is shown. Latent heat is defined, and the Clausius–Clapeyron equation is derived. Gibbs' phase rule is derived and illustrated.

scholarly journals The Effect of Selected Anions on Dipalmitoylphosphatidylcholine Phase Transitions

2002 ◽  
Vol 57 (7-8) ◽  
pp. 712-716 ◽  
Author(s):  
Adriana Przyczyna ◽  
Bożenna Różycka-Roszk ◽  
Marek Langner
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Salt Concentration ◽  
Half Width ◽  
Main Phase ◽  
Interface Properties ◽  
Transition Enthalpy ◽  
Peak Half Width

The effect of three anions, Cl-, Br- and I-, on the phase transitions of dipalmitoylphosphatidylcholine (DPPC) was measured. Main phase transition was modestly affected by these anions in the salt concentration range 0.2 M. For Cl- and Br- the temperature of main phase transition was lower (by about 0.5 °C), its half-width modestly larger and enthalpy practically unchanged, all three parameters were altered to a much larger degree. Main phase transition temperature was 1.5 °C lower and the peak half-width significantly smaller. These changes were not accompanied by any alteration in main phase transition enthalpy. Iodide shifted the pretransition temperature toward lower values and increased its half-width to such an extent that at concentrations above 100 mm it was practically undetectable. Besides cations, the presence of anions also has a distinct effect on lipid bilayer interface properties.

Direct Synthesis of Chromium Perovskite Oxyhydride with a High Magnetic-Transition Temperature

2014 ◽  
Vol 126 (39) ◽  
pp. 10545-10548 ◽  
Author(s):  
Cédric Tassel ◽  
Yoshihiro Goto ◽  
Yoshinori Kuno ◽  
James Hester ◽  
Mark Green ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Magnetic Transition ◽  
Direct Synthesis ◽  
Magnetic Transition Temperature

Magnetic Phase Transitions and Magnetocaloric Effect in R2Fe17 (R = Y, Tb, Er)

2015 ◽  
Vol 233-234 ◽  
pp. 204-207 ◽  
Author(s):  
S.A. Nikitin ◽  
I.A. Ovchenkova ◽  
Georgiy A. Tskhadadze ◽  
Konstantin P. Skokov
Keyword(s):  
Transition Temperature ◽  
Magnetocaloric Effect ◽  
Magnetic Phase ◽  
Magnetic Transition ◽  
Exchange Interactions ◽  
Thermodynamic Theory ◽  
Magnetic Phase Transitions ◽  
Magnetic Transition Temperature ◽  
Local Fluctuations ◽  
Direct Measurements

The direct measurements of the magnetocaloric effect (MCE) and the magnetization for R2Fe17 (R = Y, Tb, Dy) compounds are reported. The maximal values of the MCE for different R2Fe17 compounds are almost the same at the Curie temperature and are equal to 0.8 – 0.85 K at ΛH = 13.5 kOe. The field dependencies of the magnetization and MCE and the dependence of MCE via magnetization deviates from the classical regularities and describes by the thermodynamic theory attracting the higher terms. Obviously the occurrence of the mixed exchange interactions in these compounds leads to the requirement of consideration both thermal and local fluctuations of the exchange integrals near the magnetic transition temperature.

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