Effects of temperature and electric field on order parameters in ferroelectric hexagonal manganites

Abstract

In Landau-Devonshire phase transition theory, the order parameter represents a unique property for a disorder-order transition at the critical temperature. Nevertheless, for a phase transition with more than one order parameter, such behaviors can be quite different and system-dependent in many cases. In this work, we investigate the temperature (T) and electric field (E) dependence of the two order parameters in improper ferroelectric hexagonal manganites, addressing the phase transition from the high-symmetry P6 3 /mmc structure to the polar P6 3 cm structure. It is revealed that the trimerization as the primary order parameter with two components: the trimerization amplitude Q and phase U, and the spontaneous polarization P emerging as the secondary order parameter exhibit quite different stability behaviors against various T and E. The critical exponents for the two parameters Q and P are 1/2 and 3/2, respectively. As temperature increases, the window for the electric field E enduring the trimerization state will shrink. An electric field will break the Z 2 part of the Z 2 ÂZ 3 symmetry. The present work may shed light on the complexity of the vortex-antivortex domain structure evolution near the phase transition temperature.

Динамика Предельно Коротких Импульсов В Примесных Двухуровневых Системах В Рамках Подхода Глаубера-=sup=-1-=/Sup=-

“…Широко известно, что сегнетоэлектрики являются удобным средством изучения структурных фазовых переходов (ФП), испытывая ФП второго рода типа " порядок−беспорядок" [6]. Это позволяет управлять их свойствами при помощи изменения температуры [7]. Отметим также, что двухуровневая система представляет собой простейшую квантовую модель, которая используется при изучении взаимодействия света с веществом.…”

Dynamics of extremely short pulses in two-level impurity systems in the framework of the glauber approach-=SUP=-1-=/SUP=-

“…It is widely known that ferroelectrics are a convenient means of studying structural phase transitions (PT) by experiencing a PT of the second kind " order−disorder" [6]. This allows you to control their properties by changing the temperature [7]. Note also that a two-level system is the simplest quantum model that is used in studying the interaction of light with matter.…”