Structural dynamics in hybrid halide perovskites: Bulk Rashba splitting, spin texture, and carrier localization

Zheng, Chao; Yu, Shidong; Rubel, Oleg

doi:10.1103/physrevmaterials.2.114604

Cited by 23 publications

(34 citation statements)

References 52 publications

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“…Symmetry considerations point toward the existence of electronic symmetries that are not revealed in static DFT calculations, supporting the presence of significant dynamical symmetry breaking mechanisms that have recently been suggested. 26,[56][57][58] This demonstrates the critical role of the experimental geometry in the optical characterization of novel 2D materials, and likely accounts for the wide variation of previous interpretations of sideband emission in HOIPs.…”

Section: Bodymentioning

confidence: 75%

Bright magnetic dipole radiation from two-dimensional lead-halide perovskites

et al. 2020

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Light-matter interactions in semiconductor systems are uniformly treated within the electric dipole (ED) approximation, as multipolar interactions are considered "forbidden". Here, we demonstrate that this approximation inadequately describes light emission in novel two-dimensional hybrid organic-inorganic perovskite materials (2D HOIPs) -a class of solution processable layered semiconductor with promising optoelectronic properties. Consequently, photoluminescence (PL) spectra become strongly dependent on the experimental geometry, a fact that is often overlooked, though critical for correct optical characterization of materials. Using energy-momentum and time-resolved spectroscopies, we experimentally demonstrate that low-energy sideband emission in 2D HOIPs exhibits a highly unusual, multipolar polarization and angle dependence. Using combined electromagnetic and quantum-mechanical analyses, we attribute this radiation pattern to an out-of-plane oriented magnetic dipole transition arising from the 2D character of the excited and ground state orbitals. Symmetry arguments point toward the presence of significant inversion symmetry-breaking mechanisms that are currently under great debate. These results provide a new perspective on the origins of unexpected sideband emission in HOIPs, clarify discrepancies in previous literature, and generally challenge the paradigm of ED-dominated light-matter interactions in novel optoelectronic materials. 1 arXiv:1901.05136v2 [cond-mat.mtrl-sci]

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Section: Bodymentioning

confidence: 75%

Bright magnetic dipole radiation from two-dimensional lead-halide perovskites

et al. 2020

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“…This underestimation was due to the lack of stochastic thermal distortions of the PbI 6 octahedra, which further opened the gap by ca. 0.5 eV at room temperature [35,36]. Table 6 captures the matrix elements and their anisotropy caused by the reduced (pseudo-cubic) symmetry of the unit cell.…”

Section: Illustrative Applicationsmentioning

confidence: 99%

Length-Gauge Optical Matrix Elements in WIEN2k

Rubel

Blaha

2022

Computation

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Hybrid exchange-correlation functionals provide superior electronic structure and optical properties of semiconductors or insulators as compared to semilocal exchange-correlation potentials due to admixing a portion of the non-local exact exchange potential from a Hartree–Fock theory. Since the non-local potential does not commute with the position operator, the momentum matrix elements do not fully capture the oscillator strength, while the length-gauge velocity matrix elements do. So far, length-gauge velocity matrix elements were not accessible in the all-electron full-potential WIEN2k package. We demonstrate the feasibility of computing length-gauge matrix elements in WIEN2k for a hybrid exchange-correlation functional based on a finite difference approach. To illustrate the implementation we determined matrix elements for optical transitions between the conduction and valence bands in GaAs, GaN, (CH3NH3)PbI3 and a monolayer MoS2. The non-locality of the Hartree–Fock exact exchange potential leads to a strong enhancement of the oscillator strength as noticed recently in calculations employing pseudopotentials (Laurien and Rubel: arXiv:2111.14772 (2021)). We obtained an analytical expression for the enhancement factor for the difference in eigenvalues not captured by the kinetic energy. It is expected that these results can also be extended to other non-local potentials, e.g., a many-body GW approximation.

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“…This underestimation is due to the lack of stochastic thermal distortions of the PbI 6 octahedra, which further opens the gap by ca. 0.5 eV at room temperature [33,34]. Table VI captures the matrix elements and their anisotropy caused by a reduced (pseudo-cubic) symmetry of the unit cell.…”

Section: Illustrative Applicationsmentioning

confidence: 99%

Length-gauge optical matrix elements in WIEN2k

Rubel,

Blaha

2021

Preprint

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Hybrid exchange-correlation functionals provide superior electronic structure and optical properties of semiconductors or insulators as compared to semilocal exchange-correlation potentials due to admixing a portion of the non-local exact exchange potential from a Hartree-Fock theory.Since the non-local potential does not commute with the position operator, the momentum matrix elements do not fully capture the oscillator strength, while the length-gauge velocity matrix elements do. So far, length-gauge velocity matrix elements were not accessible in the all-electron full-potential WIEN2k package. We demonstrate the feasibility of computing length-gauge matrix elements in WIEN2k for a hybrid exchange-correlation functional based on a finite difference approach. To illustrate the implementation we determined matrix elements for optical transitions between the conduction and valence bands in GaAs, GaN, (CH 3 NH 3 )PbI 3 and a monolayer MoS 2 .The non-locality of the Hartree-Fock exact exchange potential leads to a strong enhancement of the oscillator strength as noticed recently in calculations employing pseudopotentials [Laurien and Rubel: arXiv:2111.14772 (2021)]. We obtained an analytical expression for the enhancement factor in terms of the difference in eigenvalues not captured by the kinetic energy. It is expected that these results can also be extended to other non-local potentials, e.g., a many-body GW approximation.This paper is dedicated to the 80 th birthday of Professor Karlheinz Schwarz, the founder of the WIEN2k DFT package. I. INTRODUCTIONCalculations of linear optical properties of solids require matrix elements for electric dipole transitions. Momentum matrix elementsare widely used in full-potential codes with periodic boundary conditions [1] when optical properties are computed with local potentials (e.g., LDA or GGA XC functionals) and referred in the literature as a velocity gauge. (Atomic units will be used throughout the paper.

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Structural dynamics in hybrid halide perovskites: Bulk Rashba splitting, spin texture, and carrier localization

Cited by 23 publications

References 52 publications

Bright magnetic dipole radiation from two-dimensional lead-halide perovskites

Bright magnetic dipole radiation from two-dimensional lead-halide perovskites

Length-Gauge Optical Matrix Elements in WIEN2k

Length-gauge optical matrix elements in WIEN2k

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