20 research outputs found
On the theory of phase transition in muliferroics
In this paper we investigate peculiarities of phase transition high-symmetry
- incommensurate phase in inhomogeneous systems. We obtain the nonlinear
dispersion law and then present a renormalization group analysis of phase
transitions in multiferroics. We have determined the dependence of critical
indices on the nonextensivity parameter of the system
Electronic properties and phase transitions in low-dimensional semiconductors
We present the first review of the current state of the literature on
electronic properties and phase transitions in TlX and TlMX2 (M = Ga, In; X =
Se, S, Te) compounds. These chalcogenides belong to a family of the
low-dimensional semiconductors possessing chain or layered structure. They are
of significant interest because of their highly anisotropic properties, semi-
and photoconductivity, non-linear effects in their I-V characteristics
(including a region of negative differential resistance), switching and memory
effects, second harmonic optical generation, relaxor behavior and potential
applications for optoelectronic devices. We review the crystal structure of TlX
and TlMX2 compounds, their transport properties under ambient conditions,
experimental and theoretical studies of the electronic structure, transport
properties and semiconductor-metal phase transitions under high pressure, and
sequences of temperature-induced structural phase transitions with intermediate
incommensurate states. Electronic nature of the ferroelectric phase transitions
in the above-mentioned compounds, as well as relaxor behavior, nanodomains and
possible occurrence of quantum dots in doped and irradiated crystals is
discussed.Comment: 70 pages, 38 figure