Temperature dependence of the magnetic excitations in the modified triangular induced moment antiferromagnet RbFeBr3 at the soft mode point (abstract)

1991 ◽  
Vol 69 (8) ◽  
pp. 6232-6232 ◽  
Author(s):  
D. Visser ◽  
B. Dorner ◽  
A. Harrison
Keyword(s):  
Temperature Dependence ◽  
Soft Mode ◽  
Magnetic Excitations

The temperature dependence of the photoinduced soft mode in Sn2P2S6 crystal

2019 ◽  
Vol 33 (08) ◽  
pp. 1950061
Author(s):  
K. A. Brekhov ◽  
N. A. Ilyin ◽  
E. D. Mishina ◽  
P. A. Prudkovskii ◽  
G. Kh. Kitaeva
Keyword(s):  
Phase Transition ◽  
Femtosecond Laser ◽  
Curie Temperature ◽  
Temperature Dependence ◽  
Oscillation Frequency ◽  
Phonon Mode ◽  
Soft Mode ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Curie Temperature Tc

In this paper, we present the results of the temperature dependence studies of the photoinduced phonon mode which appears in a ferroelectric-semiconductor Sn2P2S6 (SPS) crystal under the influence of femtosecond laser pulses. We show that its behavior reminds the soft mode one near the phase transition. However, the observed decrease in the oscillation frequency in the vicinity of Curie temperature Tc is much weaker than previously reported. This can be explained by the shadowing of the pure soft mode by its interaction with other photoinduced modes.

Temperature dependence of the magnetic excitations in Nd2CuO4

1999 ◽  
Vol 196-197 ◽  
pp. 473-474
Author(s):  
A. Metz ◽  
N.M. Pyka ◽  
M. Loewenhaupt ◽  
A.A. Menovsky ◽  
R. van de Kamp
Keyword(s):  
Temperature Dependence ◽  
Magnetic Excitations

Theory of Ferroelectric Phase Transitions in Pure and Mixed Perovskites.

2002 ◽  
Vol 718 ◽  
Author(s):  
Yizhak Yacoby ◽  
Yakov Girshberg
Keyword(s):  
Temperature Dependence ◽  
Ferroelectric Phase ◽  
Paraelectric Phase ◽  
Soft Mode ◽  
Critical Concentration ◽  
Comprehensive Model ◽  
Coupling Constant ◽  
Phonon Coupling ◽  
Ferroelectric Phase Transitions ◽  
Basic Experimental Data

AbstractWe present a comprehensive model of ferroelectricity in oxygen perovskite crystals that account quantitatively for both displacive like and order-disorder like properties. The model assumes that in the paraelectric phase, the system has a soft mode, interacting with spontaneous disordered off-center displacements. The resulting theory is shown to quantitatively explain the properties of two representative perovskites: KNbO3 and PbTiO3. We have further extended this theory to explain the properties of mixed incipient ferroelectrics with small concentrations of ferroelectricity inducing ions such as KTa1-xNbxO3. The model quantitatively reproduces the basic experimental data in the quantum regime: the temperature dependence of the inverse dielectric function, the impurity and temperature dependence of the renormalized soft mode vibrational frequency and the impurity concentration dependence of the transition temperature Tc. In particular we show that, the critical concentration for Tc=0 is determined by the ion tunneling frequency, the bare soft mode parameters and the pseudospin - phonon coupling constant.

On the temperature dependence of the magnetic excitations

2005 ◽  
Vol 364 (1-4) ◽  
pp. 55-70 ◽  
Author(s):  
U. Köbler ◽  
A. Hoser ◽  
W. Schäfer
Keyword(s):  
Temperature Dependence ◽  
Magnetic Excitations

scholarly journals Temperature dependence of the magnetic excitations in Gd

1981 ◽  
Vol 52 (3) ◽  
pp. 2231-2233 ◽  
Author(s):  
J. W. Cable ◽  
N. Wakabayashi ◽  
R. M. Nicklow
Keyword(s):  
Temperature Dependence ◽  
Magnetic Excitations

Temperature Dependence of Soft Mode Frequency and Dielectric Constant in Ferroelectric PbHPO[sub 4] Crystal

2011 ◽  
Author(s):  
Trilok Chandra Upadhayay ◽  
Mayank Joshi ◽  
P. K. Bajpai ◽  
K. S. Ojha ◽  
K. N. Singh
Keyword(s):  
Dielectric Constant ◽  
Temperature Dependence ◽  
Soft Mode ◽  
Mode Frequency

scholarly journals Calculation of the Spontaneous Polarization and the Dielectric Constant as a Function of Temperature for

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Hamit Yurtseven ◽  
Sema Şen
Keyword(s):  
Dielectric Constant ◽  
Transition Temperature ◽  
Temperature Dependence ◽  
Spontaneous Polarization ◽  
Atmospheric Pressure ◽  
Ferroelectric Phase ◽  
Paraelectric Phase ◽  
Soft Mode ◽  
Increasing Temperature ◽  
Mode Response

The temperature dependence of the spontaneous polarizationPis calculated in the ferroelectric phase of KH2PO4(KDP) at atmospheric pressure (TC= 122 K). Also, the dielectric constantεis calculated at various temperatures in the paraelectric phase of KDP at atmospheric pressure. For this calculation ofPandε, by fitting the observed Raman frequencies of the soft mode, the microscopic parameters of the pure tunnelling model are obtained. In this model, the proton-lattice interaction is not considered and the collective proton mode is identified with the soft-mode response of the system. Our calculations show that the spontaneous polarization decreases continuously in the ferroelectric phase as approaching the transition temperatureTC. Also, the dielectric constant decreases with increasing temperature and it diverges in the vicinity of the transition temperature (TC= 122 K) for KDP according to the Curie-Weiss law.

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