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Room-temperature magnon-phonon transduction in high-damping Co/Pt structures
Authors:
Gauravkumar Patel,
Takuma Sato,
Maximilian Frenzel,
Prakriti P. Joshi,
Ruslan Salikhov,
Ievgeniia Korniienko,
Dominik Legut,
Olav Hellwig,
Sebastian F. Maehrlein,
Kilian Lenz,
Jürgen Lindner
Abstract:
Quantum communication and information processing strongly benefit from the coupling between different quasi-particles, offering complementary advantages. Magnetoelastic materials inherently allow for direct coupling between magnetization dynamics and quantized lattice vibrations, called phonons. Near the ferromagnetic resonances, phonons may thus trade energy and angular momentum with uniformly pr…
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Quantum communication and information processing strongly benefit from the coupling between different quasi-particles, offering complementary advantages. Magnetoelastic materials inherently allow for direct coupling between magnetization dynamics and quantized lattice vibrations, called phonons. Near the ferromagnetic resonances, phonons may thus trade energy and angular momentum with uniformly precessing magnetization, called magnons, and enable transduction of information from magnetic to phononic modes, thereby paving the way for long-range transport of magnetic information without the need of magnetic material. Here, we employ tailored magnetic-nonmagnetic heterostructures, which simultaneously act as cavities for standing shear waves, to bring selective phonons and magnons into resonance. These Co films with Pt seed layers show extended linewidth and reduced amplitude of the phonon-resonant FMR lines, providing a hallmark of energy and angular momentum exchange. Complementarily, by theoretical modeling and ultra-fast coherent phonon spectroscopy, we identify the responsible transverse acoustic phonons as standing shear waves in the combined Co and Pt structure. We find a high crystal quality in conjunction with a large magnetoelastic coupling constant as a prerequisite for efficient magnon-phonon coupling of this type. Such resonant enhancement of magnon-phonon coupling in CMOS-compatible material provides an ideal material platform for future quantum transducers.
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Submitted 26 June, 2026;
originally announced June 2026.
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Wrinkle Mediated Phase Transitions in In$_2$Se$_3$
Authors:
Joseph L. Spellberg,
Lina Kodaimati,
Atreyie Ghosh,
Prakriti P. Joshi,
Sarah B. King
Abstract:
Crystalline phase transitions in two-dimensional materials enable precise control over electronic and ferroic properties, making them attractive materials for memory and energy storage applications. In$_2$Se$_3$ is particularly promising because its $α$ and $β'$ phases are both stable at room temperature but exhibit distinct ferroic behaviors. However, achieving reliable reversible switching betwe…
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Crystalline phase transitions in two-dimensional materials enable precise control over electronic and ferroic properties, making them attractive materials for memory and energy storage applications. In$_2$Se$_3$ is particularly promising because its $α$ and $β'$ phases are both stable at room temperature but exhibit distinct ferroic behaviors. However, achieving reliable reversible switching between these states remains challenging. Here, we show that controlled $β'\rightarrowα$ phase transitions in 2D In$_2$Se$_3$ become accessible through laser-induced wrinkling, establishing a room-temperature approach for manipulating ferroic states in In$_2$Se$_3$ thin films. Combined with thermal annealing for phase recovery, this approach eliminates cryogenic steps and mechanical perturbation while harnessing accumulated internal strain to generate multiphase heterostructures and direct domain reorganization. This pathway for phase transitions in In$_2$Se$_3$ opens the door for further development in ferroic device architectures and phase-change memory technologies.
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Submitted 22 July, 2025;
originally announced July 2025.
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Nano-imaging of the edge-dependent optical polarization anisotropy of black phosphorus
Authors:
Prakriti P. Joshi,
Ruiyu Li,
Joseph L. Spellberg,
Liangbo Liang,
Sarah B. King
Abstract:
The electronic structure and functionality of 2D materials is highly sensitive to structural morphology, opening the possibility for manipulating material properties, but also making predictable and reproducible functionality challenging. Black phosphorus (BP), a corrugated orthorhombic 2D material, has in-plane optical absorption anisotropy critical for applications such as directional photonics,…
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The electronic structure and functionality of 2D materials is highly sensitive to structural morphology, opening the possibility for manipulating material properties, but also making predictable and reproducible functionality challenging. Black phosphorus (BP), a corrugated orthorhombic 2D material, has in-plane optical absorption anisotropy critical for applications such as directional photonics, plasmonics, and waveguides. Here, we use polarization-dependent photoemission electron microscopy to visualize the anisotropic optical absorption of BP with 54 nm spatial resolution. We find the edges of BP flakes have a shift in their optical polarization anisotropy from the flake interior due to the 1D confinement and symmetry reduction at flake edges that alter the electronic charge distributions and transition dipole moments of edge electronic states, confirmed with first-principles calculations. These results uncover previously hidden modification of the polarization-dependent absorbance at the edges of BP, highlighting the opportunity for selective excitation of edge states of 2D materials with polarized light.
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Submitted 6 April, 2022; v1 submitted 5 October, 2021;
originally announced October 2021.
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Decoding Ultrafast Polarization Responses in Lead Halide Perovskites by the Two-Dimensional Optical Kerr Effect
Authors:
Sebastian F. Maehrlein,
Prakriti P. Joshi,
Lucas Huber,
Feifan Wang,
Marie Cherasse,
Yufeng Liu,
Dominik M. Juraschek,
Edoardo Mosconi,
Daniele Meggiolaro,
Filippo de Angelis,
X. -Y. Zhu
Abstract:
The ultrafast polarization response to incident light and ensuing exciton/carrier generation are essential to outstanding optoelectronic properties of lead halide perovskites (LHPs). A large number of mechanistic studies in the LHP field to date have focused on contributions to polarizability from organic cations and the highly polarizable inorganic lattice. For a comprehensive understanding of th…
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The ultrafast polarization response to incident light and ensuing exciton/carrier generation are essential to outstanding optoelectronic properties of lead halide perovskites (LHPs). A large number of mechanistic studies in the LHP field to date have focused on contributions to polarizability from organic cations and the highly polarizable inorganic lattice. For a comprehensive understanding of the ultrafast polarization response, we must additionally account for the nearly instantaneous hyperpolarizability response to the propagating light field itself. While light propagation is pivotal to optoelectronics and photonics, little is known about this in LHPs in the vicinity of the bandgap where stimulated emission, polariton condensation, superfluorescence, and photon recycling may take place. Here we develop two-dimensional optical Kerr effect (2D-OKE) spectroscopy to energetically dissect broadband light propagation and dispersive nonlinear polarization responses in LHPs. In contrast to earlier interpretations, the below-bandgap OKE responses in both hybrid CH3NH3PbBr3 and all-inorganic CsPbBr3 perovskites are found to originate from strong hyperpolarizability and highly anisotropic dispersions. In both materials, the nonlinear mixing of anisotropically propagating light fields result in convoluted oscillatory polarization dynamics. Based on a four-wave mixing model, we quantitatively derive dispersion anisotropies, reproduce 2D-OKE frequency correlations, and establish polarization dressed light propagation in single crystal LHPs. Moreover, our findings highlight the importance of distinguishing the often-neglected anisotropic light propagation from underlying coherent quasi-particle responses in various forms of ultrafast spectroscopy.
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Submitted 24 October, 2020; v1 submitted 15 August, 2020;
originally announced August 2020.
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Experimental demonstration of correlated flux scaling in photoconductivity and photoluminescence of lead-halide perovskites
Authors:
Hee Taek Yi,
Pavel Irkhin,
Prakriti P. Joshi,
Yuri N. Gartstein,
Xiaoyang Zhu,
Vitaly Podzorov
Abstract:
Lead-halide perovskites attracted attention as materials for high-efficiency solar cells and light emitting applications. Among their attributes are solution processability, high absorbance in the visible spectral range and defect tolerance, as manifested in long photocarrier lifetimes and diffusion lengths. The microscopic origin of photophysical properties of perovskites is, however, still uncle…
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Lead-halide perovskites attracted attention as materials for high-efficiency solar cells and light emitting applications. Among their attributes are solution processability, high absorbance in the visible spectral range and defect tolerance, as manifested in long photocarrier lifetimes and diffusion lengths. The microscopic origin of photophysical properties of perovskites is, however, still unclear and under debate. Here, we have observed an interesting universal scaling behavior in a series of (hybrid and all-inorganic) perovskite single crystals investigated via simultaneous measurements of the Hall effect, photoconductivity and photoluminescence. A clear correlation between photoconductivity and photoluminescence as functions of the incident photon flux is observed. While photoconductivity exhibits a crossover in the power-law dependence between power exponents 1 and 1/2, photoluminescence exhibits a crossover between power exponents 2 and 3/2. This correlation is found in all the studied compounds irrespective of the cation type (organic or inorganic) or crystallographic phases. We propose phenomenological microscopic mechanisms that explain these interesting non-trivial power exponents and crossovers between them in this broad class of lead-halide perovskites.
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Submitted 30 March, 2018;
originally announced April 2018.