Gyrotropic phase transitions

Koňák, Čestmı́r; Kopský, V.; Smutný, F.

doi:10.1088/0022-3719/11/12/012

Cited by 34 publications

(19 citation statements)

References 39 publications

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“…Interestingly, Fig. 4 further shows that all the ferroelectric vortices have exactly the same chirality, which is consistent with the fact that P 2 1 2 1 2 1 phases are allowed to have non-zero optical activity tensors [20] and non-zero gyrotropic tensors [18]. In fact, the P nmato-P 2 1 2 1 2 1 phase transitions fall in the category of the so-called gyrotropic phase transitions, that are characterized by the appearance of a spontaneous optical activity [16][17][18][19][20].…”

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confidence: 76%

“…This unusual coexistence of several order parameters leads to the formation of interpenetrated arrays of ferroelectric vortices and antivortices in the P 2 1 2 1 2 1 state never seen before in any ferroelectric bulk. Furthermore, the P nma-to-P 2 1 2 1 2 1 phase transition constitutes a rare example [16] of a so-called gyrotropic phase transition (that is characterized by the appearance of a spontaneous optical activity) [17][18][19][20]. In fact, to the best of our knowledge, this study reports the first pure gyrotropic phase transition ever predicted or observed in a perovskite material.…”

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confidence: 69%

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Phase Transitions in Epitaxial (−110)BiFeO3Films from First Principles

2011

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The effect of misfit strain on properties of epitaxial BiFeO3 films that are grown along the pseudocubic [110] direction, rather than along the usual [001] direction, is predicted from density-functional theory. These films adopt the monoclinic Cc space group for compressive misfit strains smaller in magnitude than ≃1.6% and for any investigated tensile strain. In this Cc phase, both polarization and the axis about which antiphase oxygen octahedra tilt rotate within the epitaxial plane as the strain varies. Surprisingly and unlike in (001) films, for compressive strain larger in magnitude than ≃1.6%, the polarization vanishes and two orthorhombic phases of Pnma and P2(1)2(1)2(1) symmetry successively emerge via strain-induced transitions. The Pnma-to-P2(1)2(1)2(1) transition is a rare example of a so-called pure gyrotropic phase transition, and the P2(1)2(1)2(1) phase exhibits original interpenetrated arrays of ferroelectric vortices and antivortices.

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confidence: 69%

Phase Transitions in Epitaxial (−110)BiFeO3Films from First Principles

2011

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“…Such group-theoretical analysis can be useful in the investigation of some phase transitions. 24 is important, that this method can be applied in the gyrotropic crystals, where the electromagnetic wave spec-…”

Section: Discussionmentioning

confidence: 99%

Vibrational circular dichroism and vibrational optical rotatory dispersion in molecular crystals. II. Selection rules

Lalov

Kotzev

1984

The Journal of Chemical Physics

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The selection rules for the contribution of the electric and magnetic dipole and electric quadrupole moments of the optical active vibrations to the gyrotropy of molecular crystals are derived by group-theoretical analysis. The peculiarities of nondegenerate and degenerate vibration modes are discussed. The selection rules for k → 0 case are tabulated for all 32 crystal classes, taking into account the time-reversal symmetry and Wigner co-representation theory.

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“…The simplicity of the method is rather well illustrated by a paper on gyrotropic phase transitions [42]. The first table (Table 2) you see below defines representations of the group D 4z in a specific orientation.…”

Section: Magnetoelectricitymentioning

confidence: 99%

Crystallography and Magnetic Phenomena

Kopský¹

2015

Symmetry

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This essay describes the development of groups used for the specification of symmetries from ordinary and magnetic point groups to Fedorov and magnetic space groups, as well as other varieties of groups useful in the study of symmetric objects. In particular, we consider the problem of some incorrectness in Vol. A of the International Tables for Crystallography. Some results of tensor calculus are presented in connection with magnetoelectric phenomena, where we demonstrate the use of Ascher's trinities and Opechowski's magic relations and their connection. Specific tensor decomposition calculations on the grounds of Clebsch Gordan products are illustrated.

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Gyrotropic phase transitions

Cited by 34 publications

References 39 publications

Phase Transitions in Epitaxial (−110)BiFeO3Films from First Principles

Phase Transitions in Epitaxial (−110)BiFeO3Films from First Principles

Vibrational circular dichroism and vibrational optical rotatory dispersion in molecular crystals. II. Selection rules

Crystallography and Magnetic Phenomena

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