Anisotropic photostriction and deformation potentials in perovskite semiconductors

Mikhail Nestoklon^a

^aTechnische Universität Dortmund, 44227 Dortmund, Germany

Proceedings of MATSUS Spring 2026 Conference (MATSUSSpring26)

H2 Halide perovskites for quantum technologies

Barcelona, Spain, 2026 March 23rd - 27th

Organizers: Quinten Akkerman, Simon Boehme and Maksym Kovalenko

Oral, Mikhail Nestoklon, presentation 336
Publication date: 15th December 2025

Perovskite semiconductors attract a lot of attention due to their intriguing optical and electrical properties. Ultrafast spectroscopy of coherent acoustic phonons employs excitation and detection by short femtosecond laser pulses in pump-probe techniques, representing a powerful method to investigate the lattice dynamics. This method exploits excitation of stress associated with the thermoelastic coupling in metals or with the photostriction in semiconductors. In most settings, the longitudinal acoustic (LA) phonons are generated. The methods to induce transverse acoustic (TA, shear) phonons: excitation at the crystalline surface of low symmetry [1] and the inverse piezoelectric mechanism [2] fail in centrosymmetric halide perovskites, where the mechanisms of generation of shear acoustic waves are still under debate.
In [3], a new mechanism for efficient optical generation of shear strain in perovskite semiconductors via the giant anisotropic photostriction of the tetragonal crystal lattice is revealed and elaborated. Coherent TA phonons with amplitudes comparable to LA modes are observed in the tetragonal phase of a Cs₂AgBiBr₆ crystal using time-domain Brillouin spectroscopy by femtosecond laser pulses. One of the two TA modes is excited with polarization direction given by the projection of the c-axis on the sample surface. In cubic phase only LA strain pulse is generated. The weak temperature dependence of the photogenerated coherent phonons provides evidence for the non-thermal nature of the effect, i.e., for the photostrition.
To further elaborate the microscopic origin of the giant anisotropic photostriction, the DFT calculations were performed. The calculations reproduce different sign of photostriction in teteragonal phase of CsPbI₃ [4] and predict similar effect in teteragonal double perovskite Cs₂AgBiBr₆. Calculations of deformation potentials demonstrate the essential importance of the optical deformation potential of the mode associated with octahedron rotation mode in Γ-point.

References:

[1] Matsuda, O.; Wright, O. B.; Hurley, D. H.; Gusev, V. ; Shimizu, K. Coherent shear phonon generation and detection with picosecond laser acoustics. Phys. Rev. B 2008, 77, 224110.

[2] Ruello, P.; Gusev, V. E. Physical mechanisms of coherent acoustic phonons generation by ultrafast laser action” Ultrasonics 2015, 56, 21.

[3] Horiachyi, D.O.; Nestoklon, M.O.; Akimov, I.A.; Trifonov, A.V.; Siverin, N.V.; Kopteva, N.E.; Kosarev, A.N.; Yakovlev, D.R.; Gusev, V.E.; Fries, M.; Trukhina, O.; Dyakonov, V.; Bayer, M. Efficient launching of shear phonons in photostrictive halide perovskites. Science Adv. 2025, 11, eadw9172.

[4] Paillard, C.; Bellaiche, L. Light: A new handle to control the structure of cesium lead iodide”, Phys. Rev. B 2003, 107, 054107.

Acknowledgements:

Author acknowledges the financial support by the Deutsche Forschungsgemeinschaft within the SPP 2196 (project AK40/13-1, no. 506623857)

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