Ferroelectric transition in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Y</mml:mi><mml:mi mathvariant="normal">Mn</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>from first principles

Fennie, Craig J.; Rabe, Karin M.

doi:10.1103/physrevb.72.100103

Cited by 408 publications

(419 citation statements)

References 24 publications

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“…Our model is based on the general expression for the free energy of the hexagonal RMnO 3 series obtained from group theoretical considerations [21][22][23] and confirmed by DFT. 22 More specifically, DFT reveals that the K 3 mode nearly displays a continuous U (1) …”

Section: Monte-carlo (Mc) Simulationsmentioning

confidence: 99%

“…On the theoretical side, the two-transition scenario has initially been supported by density-functional-theory calculations 20 . A more detailed analysis, however, suggests improper ferroelectricity triggered by the lattice trimerization in a single-step transition 21,22 , in which secondary anomalies are yet possible due to the breaking of residual symmetries 23 . Direct measurement of the spontaneous polarization as function of temperature would clarify this puzzling situation.…”

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confidence: 99%

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Ferroelectricity in the multiferroic hexagonal manganites

et al. 2015

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1The emergence of the spontaneous polarization in the hexagonal RMnO 3 system (R = Sc, Y, In, Dy -Lu) is one of the singular properties and, at the same time, one of the greatest mysteries of this class of compounds. Taking YMnO 3 as reference compound for the series (see Methods), Curie temperatures inexplicably spreading from 910 K to 1250 K have been reported 10-16, 18, 19 . In some of these cases ferroelectricity has been claimed to emerge together with a trimerizing lattice distortion in a single-step transition 16,18,19 . In other cases these two features have been proposed to occur separately [10][11][12][13][14][15] . On the theoretical side, the two-transition scenario has initially been supported by density-functional-theory calculations 20 . A more detailed analysis, however, suggests improper ferroelectricity triggered by the lattice trimerization in a single-step transition 21,22 , in which secondary anomalies are yet possible due to the breaking of residual symmetries 23 . Direct measurement of the spontaneous polarization as function of temperature would clarify this puzzling situation. This was done once in a pyrocurrent measurement which pointed to an onset of ferroelectricity at 933 K 16 . All attempts to reproduce this experiment failed, however. Thus, in spite of 50 years of research, the emergence of the polar order in the hexagonal RMnO 3 multiferroics is surrounded by contradictions. This uncertainty extends to the universality class of this ferroelectric transition, as this basic question depends on the precise nature of the state undergoing the polar instability. The universality class and the corresponding critical behavior determines important physical properties from the macro-to the nanoscale. Understanding such functionalities is infinitely more difficult if the emergence of the ferroelectric order itself is unclear. Thus, for putting the intense research on the unusual properties of ferroelectric order in the hexagonal RMnO 3 system 2, 3, 5,8,9 onto a solid basis, this situation must be resolved. 2Here we present nonlinear optical experiments in which the electromagnetic field of a frequency-doubled light wave couples directly and linearly to the spontaneous polarization of YMnO 3 .They reveal a polarization emerging at T C 1259 K with a subdued increase in amplitude showing no anomalies or discontinuities. Piezoresponse force microscopy (PFM) confirms that the ferroelectric domain pattern is seeded right below T C . Monte-Carlo simulations reveal how topologically created vortex-like defects in the MnO 5 tilt pattern determine the ferroelectric state and many of its unusual properties. In particular, we show that the "second transition" below T C is not associated to a phase transition, but caused by a finite-size scaling effect.At room temperature, the spontaneous polarization P s = 5.6 µC/cm 2 of YMnO 3 is observed together with unit-cell-trimerizing tilts of the MnO 5 bipyramids and Y displacements along the c axis. The tilt is parameterized 22, 23 by the observable amplitude ...

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Section: Monte-carlo (Mc) Simulationsmentioning

confidence: 99%

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confidence: 99%

Ferroelectricity in the multiferroic hexagonal manganites

et al. 2015

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“…A symmetry analysis [15,24,25] shows that there are three possible paths from the high temperature P6 3 /mmc phase to the room temperature ferroelectric P6 3 cm phase, summarized in figure 1. Fennie et al [25] and Kim et al [23] supported the path of a single transition (at ∼1270 K), driven by a K 3 order parameter which couples to a secondary zone centre order parameter (associated with − 2 ) to induce ferroelectricity. In contrast to this, some studies [14,24,26] have suggested one of the paths that involves an intermediate phase between the paraelectric P6 3 /mmc phase and the ferroelectric P6 3 cm phase.…”

Section: Introductionmentioning

confidence: 99%

Elastic anomalies associated with structural and magnetic phase transitions in single crystal hexagonal YMnO₃

Thomson

Chatterji

Howard

et al. 2014

J. Phys.: Condens. Matter

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Resonant ultrasound spectroscopy has been used to measure the elastic and anelastic behaviour through known structural and magnetic phase transitions in single crystal hexagonal YMnO 3 . Anomalous elastic behaviour is observed at the high temperature structural transition at ∼1260 K, with a discontinuity in the elastic constants and nonlinear recovery below T c , consistent with λeQ 2 s coupling. There is no change in dissipation associated with this high temperature transition, and no evidence in the elastic or anelastic behaviour for any secondary transition at ∼920 K, thus supporting the thesis of a single high temperature transformation. Elastic stiffening is observed on cooling through T N , in accordance with previous studies, and the excess elastic constant appears to scale with the square of the magnetic order parameter. The strains incurred at T N are a factor of ∼20 smaller than those at the structural transition, implying very weak λeQ 2 m coupling and a dominant contribution to the variation in the elastic constants from λe 2 Q 2 m . The increased acoustic dissipation above T N is consistent with an order-disorder process.

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“…But for the improper FEs, the FE mode is no longer the primary order parameter, i.e., the polarization is induced by one or two rotational modes. [13][14][15][16][17][18][19][20][21][22][23][24][25] To verify whether the ½111 -superlattice LaCoO 3 /LaAlO 3 is an improper FE or not, the stability of the FE mode will be examined. We adopt the ISOTROPY software 33 to obtain the symmetry-adapted phonon modes in the low-symmetry FE structure.…”

Section: General Design Guidelinesmentioning

confidence: 99%

“…12 The typical example of the conventional improper FEs is hexagonal manganite YMnO 3 , 13 where the FE buckling (P mode) of the Y-O planes is induced by the non-polar MnO 5 polyhedra tilt (Q mode). 13,14 The free energy expansion in this system contains the coupling term (PQ 3 ) between the Q and P, indicating that the non-polar distortion Q must be reversed. 15 The hybrid improper ferroelectricity (HIF) was recently discovered in the artificial superlattice PbTiO 3 /SrTiO 3 , 16 where the ferroelectricity is induced by a trilinear coupling (PQ 1 Q 2 ) between the FE mode (P) and two oxygen octahedral rotational modes (Q 1 and Q 2 , respectively).…”

Section: Introductionmentioning

confidence: 99%

Designing new ferroelectrics with a general strategy

Xiang

2017

npj Quant Mater

107

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The presence of a switchable spontaneous electric polarization makes ferroelectrics ideal candidates for the use in many applications such as memory and sensors devices. Since known ferroelectrics are rather limited, finding new ferroelectric materials has become a flourishing field. One promising route is to design the improper ferroelectrics. However, previous approach based on the Landau theory is not easily adopted for systems that are unrelated to the Pbnm perovskite structure. To this end, we develop a general design rule that is applicable to any system. By combining this rule with the density functional theory calculations, we identify previously unrecognized classes of ferroelectric materials. It is shown that the R3c perovskite structure can become ferroelectric by substituting half of the B-site cations. Compound ZnSrO 2 with a non-perovskite layered structure can also be ferroelectric through the anion substitution. Moreover, our approach can be used to design new multiferroics as illustrated in the case of fluorine substituted LaMnO 3 . 13 where the FE buckling (P mode) of the Y-O planes is induced by the non-polar MnO 5 polyhedra tilt (Q mode). 13,14 The free energy expansion in this system contains the coupling term (PQ 3 ) between the Q and P, indicating that the non-polar distortion Q must be reversed. 15 The hybrid improper ferroelectricity (HIF) was recently discovered in the artificial superlattice PbTiO 3 /SrTiO 3 , 16 where the ferroelectricity is induced by a trilinear coupling (PQ 1 Q 2 ) between the FE mode (P) and two oxygen octahedral rotational modes (Q 1 and Q 2 , respectively). The HIF was also found in the double-layered Ruddlesden-Popper (RP) perovskite A 3 B 2 O 7 (A=Ca, Sr; B=Mn,Ti), 17-19 the 1:1 A-cation ordering perovskite-type superlattice, 20-23 A-cation ordering RP NaRTiO 4 (R = Y, La, Nd, Sm-Ho), 24 the 2:2 B-cation ordered superlattice, 25 and metal-organic perovskite material. 26 In the above-mentioned theoretically designed FEs, one usually starts from a high-symmetry structure (e.g., cubic perovskite structure), then the effect of atomic substitution and soft phonon modulations are examined to see whether the ferroelectricity can be induced or not. Finally, the trilinear coupling mechanism is discussed to understand the origin of improper ferroelectricity. This procedure is indeed informative. However, it is tedious and its applicability to other type of compounds is limited since even the

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Ferroelectric transition inYMnO3from first principles

Cited by 408 publications

References 24 publications

Ferroelectricity in the multiferroic hexagonal manganites

Ferroelectricity in the multiferroic hexagonal manganites

Elastic anomalies associated with structural and magnetic phase transitions in single crystal hexagonal YMnO₃

Designing new ferroelectrics with a general strategy

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Ferroelectric transition inYMnO3from first principles

Cited by 408 publications

References 24 publications

Ferroelectricity in the multiferroic hexagonal manganites

Ferroelectricity in the multiferroic hexagonal manganites

Elastic anomalies associated with structural and magnetic phase transitions in single crystal hexagonal YMnO3

Designing new ferroelectrics with a general strategy

Contact Info

Product

Resources

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Elastic anomalies associated with structural and magnetic phase transitions in single crystal hexagonal YMnO₃