Mesoscopic fluctuating domains in strontium titanate

Fauqué, Benoît; Bourges, P.; Subedi, Alaska; Behnia, Kamran; Roessli, B.; Fennell, T.; Raymond, Stéphane; Steffens, P.

doi:10.1103/physrevb.106.l140301

Cited by 16 publications

(8 citation statements)

References 62 publications

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“…In both, the phonon mean-free-path is not a monotonous function of temperature, which has been tracked to abundance of momentumconserving phonon-phonon collisions 34,38 . In both, there is a non-trivial coupling between distinct phonon modes 39 .…”

Section: Discussionmentioning

confidence: 99%

The phonon thermal Hall angle in black phosphorus

Machida

Subedi

et al. 2023

Nat Commun

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The origin of phonon thermal Hall Effect (THE) observed in a variety of insulators is yet to be identified. Here, we report on the observation of a thermal Hall conductivity in a non-magnetic elemental insulator, with an amplitude exceeding what has been previously observed. In black phosphorus (BP), the longitudinal (κii), and the transverse, κij, thermal conductivities peak at the same temperature and at this peak temperature, the κij/κjj/B is ≈ 10−4−10−3 T−1. Both these features are shared by other insulators displaying THE, despite an absolute amplitude spreading over three orders of magnitude. The absence of correlation between the thermal Hall angle and the phonon mean-free-path imposes a severe constraint for theoretical scenarios of THE. We show that in BP a longitudinal and a transverse acoustic phonon mode anti-cross, facilitating wave-like transport across modes. The anisotropic charge distribution surrounding atomic bonds can pave the way for coupling between phonons and the magnetic field.

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Section: Discussionmentioning

confidence: 99%

The phonon thermal Hall angle in black phosphorus

Machida

Subedi

et al. 2023

Nat Commun

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“…Motivated by recent inelastic neutron scattering data [22], the soft modes observed in STO have been reinvestigated. In [22], special interest was devoted to the transverse optic/acoustic mode-mode coupling region, which followed the quantum fluctuation-dominated regime.…”

Section: Theorymentioning

confidence: 99%

SrTiO3: Thoroughly Investigated but Still Good for Surprises

Bussmann-Holder,

Kremer,

Roleder

et al. 2024

Condensed Matter

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For decades, SrTiO3 has been in the focus of research with seemingly never-ending new insights regarding its ground state properties, application potentials, its surface and interface properties, the superconducting state, the twin boundaries, domain functionalities, etc. Here, we focus on the already well-investigated lattice dynamics of STO and show that four different temperature regimes can be identified which dominate the elastic properties, the thermal conductivity, and the birefringence. These regimes are a low-temperature quantum fluctuation-dominated one, followed by an intermediate regime, a region of structural phase transition at ~105 K and its vicinity, and at high temperatures, a regime characterized by precursor and saturation effects. They can all be elucidated by lattice dynamical aspects. The relevant temperature dependences of the soft modes are discussed and their relationship to lattice polarizability is emphasized.

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“…Halide perovskites are of high interest due to their impressive efficiencies in solar cells 2,3 , and attractive applications in optoelectronics, electrocatalysis, and thermoelectrics [4][5][6] . Our understanding of perovskites' key properties is connected to deviations of the vibrational dynamics and electron-phonon coupling from the standard picture observed in conventional semiconductors 7,8 . For example, halide perovskites exhibit (i) ultralow thermal conductivities attributed to their low-energy vibrational densities and pecu-liar anharmonic characteristics 9,10 and (ii) limited carrier mobilities which have been discussed in terms of electron-phonon Fröhlich coupling 11 , dipolar scattering arising from anharmonic halide motion 12 , and polaronic transport 13 .…”

Section: Anharmonic Electron-phonon Coupling In Polymorphous Perovskitesmentioning

confidence: 99%

Anharmonic electron-phonon coupling in polymorphous perovskites

Zacharias

Volonakis

Giustino

et al. 2023

Preprint

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Anharmonicity and disorder are ubiquitous in the physics of perovskites and give rise to a variety of unique phenomena observed in scattering and spectroscopy experiments with profound consequences for device applications. Several of these phenomena still lack interpretation from a first-principles perspective. Recently, the concept of polymorphism has been introduced in calculations of perovskite compounds, yielding substantial improvements in describing their electronic and structural properties. However, hitherto no approach is available to account for anharmonicity and polymorphism in the phonon dynamics and electron-phonon couplings. Here, we develop a unified framework for the treatment of both relying on the special displacement method. Combining the self-consistent phonon theory of Hooton and the Allen-Heine theory of electron-phonon renormalized band structures, we demonstrate our approach for temperature-dependent band gaps of oxide and halide cubic perovskites, obtaining unprecedented agreement with experiments. We also uncover that polymorphism in halide perovskites induces phonon bunching and overdamping that lead to vibrational dynamics far from the ideal phonon picture, consistent with neutron scattering measurements. Moreover, our results suggest that accurate band gap predictions require corrections arising from polymorphism, spin-orbit coupling, hybrid functionals, and electron-phonon coupling. The present method provides the basis for investigating electron-phonon couplings in strongly anharmonic materials.

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Mesoscopic fluctuating domains in strontium titanate

Cited by 16 publications

References 62 publications

The phonon thermal Hall angle in black phosphorus

The phonon thermal Hall angle in black phosphorus

SrTiO3: Thoroughly Investigated but Still Good for Surprises

Anharmonic electron-phonon coupling in polymorphous perovskites

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