Observations of a Very Large Critical Length Scale in SrTi<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

Rj, Nelmes; Pd, Hatton; Vass, H.

doi:10.1103/physrevlett.60.2172

Cited by 20 publications

(7 citation statements)

References 15 publications

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“…Notably, these peaks occur at the R-point zone-boundary points, which should not be observed given the cubic Pm 3m crystal structure. Moreover, as a function of temperature, these features are considerably sharper (narrower) at 115 K compared to 300 K. Specifically, the average full-width at half maximum of the R-point feature changed on average by 15.8% between 300 K and 115 K. This is consistent with the trend in previous X-ray scattering experiments [41], and has been attributed to the temperature-dependent softening of the R-point phonon mode [2, 41,42,[51][52][53].…”

supporting

confidence: 87%

Validation of machine-learned interatomic potentials via temperature-dependent electron thermal diffuse scattering

Kim¹,

Xu²,

LeBeau³

2023

Preprint

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Machine-learned interatomic potentials (MLIPs) show promise in accurately describing the physical properties of materials, but there is a need for a higher throughput method of validation. Here, we demonstrate using that MLIPs and molecular dynamics can accurately capture the potential energy landscape and lattice dynamics that are needed to describe electron thermal diffuse scattering. Using SrTiO3 as a test-bed at cryogenic and room temperatures, we compare electron thermal diffuse scattering simulations using different approximations to incorporate thermal motion. Only when the simulations are based on quantum mechanically accurate MLIPs in combination with path-integral molecular dynamics that include nuclear quantum effects, there is excellent agreement with experiment

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supporting

confidence: 87%

Validation of machine-learned interatomic potentials via temperature-dependent electron thermal diffuse scattering

Kim¹,

Xu²,

LeBeau³

2023

Preprint

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“…Within neutron scattering from the system, the observation of an anomalous E 0 central peak has indicated unexpected slow or static dynamics above the phase transition [7,8]. Within x-ray scattering from the system, the observation of an anomalous central peak at the R-point in reciprocal space has indicated an unexpected second critical length scale [9][10][11][12][13][14][15]. This Letter addresses the origins and precise criticality of the x-ray critical scattering central peak component.…”

mentioning

confidence: 91%

“…The central peak critical scattering component has been previously observed in x-ray data at temperatures well above T C and has been the subject of much debate [9][10][11][12][13][14][15]. This feature has generated continuing scientific interest as it could represent a second critical length scale of the system, in principle violating the scaling hypothesis central to many modern theories of phase transitions [19].…”

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confidence: 94%

Dynamic Fluctuations and Static Speckle in Critical X-Ray Scattering fromSrTiO3

et al. 2007

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We report a study of critical x-ray scattering from SrTiO3 near the antiferrodistortive structural phase transition at T(C) approximately 105 K. A line shape analysis of the thermal diffuse scattering results in the most precise experimental determination to date of the critical exponent gamma. The microscopic mechanism behind the anomalous "central peak" critical scattering component is clarified here by the first-ever observation of a static coherent diffraction pattern (speckle pattern) within the anomalous critical scattering of SrTiO3. This observation allows us to directly attribute the origins of the central peak to Bragg diffraction from remnant static disorder above T(C).

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“…First elucidated by Larkin and Khmelnitskii [19,20], this was developed into a detailed theory by Levanyuk and Sigov [21,22], and independently, by Imry and Wortis [21]. These have been experimentally measured unambiguously by Ryan et al [22] and Nelmes et al [25] via X-ray and neutron scattering.…”

Section: Critical Phenomena In Ferroelectrics -A Quick Primermentioning

confidence: 99%

“…yielded d = 2.55±0. 25, for which the theory [4,5] predicted Λ = 1.65. Here P s is spontaneous polarization.…”

mentioning

confidence: 99%

Fractal Dimensions in Switching Kinetics of Ferroelectrics

Scott

2007

Ferroelectrics

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Early work by the author with Prof. Ishibashi [Scott et al., J. Appl. Phys. 64, 787 (1988)] showed that switching kinetics in ferroelectrics satisfy a constraint on current transients compatible with d = 2.5 dimensionality. At that time with no direct observations of the domains, it was not possible to conclude whether this was a true Hausdorff dimension or a numerical artefact caused by an approximation in the theory (which ignored the dependence of domain wall velocity upon domain diameter). Recent data suggest that the switching dimensionality is truly fractal with d = 2.5. The critical exponent β characterizing the order parameter P(T) can be written as a continuous function, which is exact within hyperscaling; here ν and η are the exponents characterizing the pair correlation function G(r,T) and the structure factor S(q,T). For d=2.5 the estimate is that β is approximately ¼. I. IntroductionTwenty years ago the author used current transients i(t) = dD/dt to determine details about switching kinetics in ferroelectric thin films; here t is time and D is the displacement vector, approximately equal to polarization P in a ferroelectric. The initial study [1] used potassium nitrate, KNO 3 , but similar studies of lead zirconate titanate PZT followed shortly thereafter [2]. Later work by Shur [3] extended this particular modelling technique. The theory used for this data-fitting was developed originally by Ishibashi and Takagi [4,5], and is based upon the analogous problem of grain growth in crystallization due to Avrami [6]. The theory is falsifiable in a nice way by the fact that it affords constraints that test the self-consistency of the model; in particular the dimensionless ratio i(p) t(p)/P s = Λ (1.)

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Observations of a Very Large Critical Length Scale in SrTiO3

Cited by 20 publications

References 15 publications

Validation of machine-learned interatomic potentials via temperature-dependent electron thermal diffuse scattering

Validation of machine-learned interatomic potentials via temperature-dependent electron thermal diffuse scattering

Dynamic Fluctuations and Static Speckle in Critical X-Ray Scattering fromSrTiO3

Fractal Dimensions in Switching Kinetics of Ferroelectrics

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