Publications of Eric Bousquet
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See detailTB2J: a python package for computing magnetic interaction parameters
He, Xu; Helbig, Nicole ULiege; Verstraete, Matthieu ULiege et al

in Computer Physics Communications (2021)

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See detailUltrafast strain engineering and coherent structural dynamics from resonantly driven optical phonons in LaAlO3
Hortensius, J. R.; Afanasiev, D.; Sasani, Alireza ULiege et al

in npj Quantum Materials (2020), 5

Strain engineering has been extended recently to the picosecond timescales, driving ultrafast metal–insulator phase transitions and the propagation of ultrasonic demagnetization fronts. However, the ... [more ▼]

Strain engineering has been extended recently to the picosecond timescales, driving ultrafast metal–insulator phase transitions and the propagation of ultrasonic demagnetization fronts. However, the nonlinear lattice dynamics underpinning interfacial optoelectronic phase switching have not yet been addressed. Here we perform time-resolved all-optical pump-probe experiments to study ultrafast lattice dynamics initiated by impulsive light excitation tuned in resonance with a polar lattice vibration in LaAlO3 single crystals, one of the most widely utilized substrates for oxide electronics. We show that ionic Raman scattering drives coherent rotations of the oxygen octahedra around a high-symmetry crystal axis. By means of DFT calculations we identify the underlying nonlinear phonon–phonon coupling channel. Resonant lattice excitation is also shown to generate longitudinal and transverse acoustic wave packets, enabled by anisotropic optically induced strain. Importantly, shear strain wave packets are found to be generated with high efficiency at the phonon resonance, opening exciting perspectives for ultrafast material control. [less ▲]

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See detailABINIT: Overview and focus on selected capabilities
Romero, Aldo ULiege; Allan, Douglas C.; Amadon, Bernard et al

in Journal of Chemical Physics (2020), 152(12), 124102

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See detailCanonical Jahn-Teller Distortion Notations: Understanding Structural-Electronic Interplays in e1g Perovskites
Schmitt, Michaël ULiege; Zhang, Yajun ULiege; Mercy, Alain ULiege et al

Scientific conference (2019, October 17)

In this talk we give a introduction to teh canonial jahn-teller distortion notations for perovskites experience metal-to-insulator transtition phenoma at elevated temperature.

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See detailAtomic structure of Sr/Si(0 0 1)(1 × 2) surfaces prepared by Pulsed laser deposition
Parkelj Potočnik, T.; Zupanič, E.; Tong, Wenyi ULiege et al

in Applied Surface Science (2019), 471

A buffer layer formed by depositing a ½ monolayer of Sr on Si(0 0 1) is known to passivate the Si surface, while its surface structure constitutes a suitable template for the integration of various ... [more ▼]

A buffer layer formed by depositing a ½ monolayer of Sr on Si(0 0 1) is known to passivate the Si surface, while its surface structure constitutes a suitable template for the integration of various functional oxides with the existing Si platform. We used Pulsed Laser Deposition (PLD) to prepare a Sr/Si(0 0 1)(1 × 2) surface and analysed it using in-situ Reflection High-Energy Diffraction (RHEED) in combination with low-temperature Scanning Tunneling Microscopy (STM). The STM images reveal an atomically ordered surface with terraces composed of one-dimensional (1D) chains running along perpendicular directions on neighbouring terraces. The 1D chains are separated by 0.78 nm and exhibit a low-amplitude corrugation with a period of 0.39 nm. The measured values agree well with the size of the (1 × 2) unit cell observed for similar MBE-grown surfaces, while the density of the surface defects is somewhat higher in the presented case. According to simulated STM images based on DFT calculations, two types of surface defects were identified and explored: arrays of Sr vacancies and Sr adatoms. These results show that PLD can offer precise control for the preparation of high-quality Sr-buffered Si(0 0 1) surfaces. © 2018 Elsevier B.V. [less ▲]

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See detailLaMnO3 Revisited
Schmitt, Michaël ULiege; Zhang, Yajun ULiege; Mercy, Alain ULiege et al

Conference (2018, June 28)

We revisit the prototypical Jahn-Teller distorted perovskite LaMnO3. We introduce a new simple notation concatenating local and cooperative aspects of Jahn-Teller distortions in perovskites on the basis ... [more ▼]

We revisit the prototypical Jahn-Teller distorted perovskite LaMnO3. We introduce a new simple notation concatenating local and cooperative aspects of Jahn-Teller distortions in perovskites on the basis of irreducible representations of phonon modes and lattice strains. This description gives a rigorous orthogonal basis to study the interlock between individual lattice distortions, strains, electronic properties and magnetic orderings. By sampling the potential energy surface of the close competing ferromagnetic and A-type antiferromagnetic orders, we show that the main parameter promoting one magnetic potential energy surface with respect to the other is the value of tetragonal strain. On the basis of this knowledge, we reinvestigate the epitaxial strain phase diagram of thin films and clarify the origin of the intriguing ferromagnetic insulating phase found in LaMnO 3 films grown on SrTiO3. Finally we discuss the possibility of designing multiferroic RMnO 3-based superlattices including strong ferromagnetism from appropriate combination of epitaxial strain and cationic ordering. [less ▲]

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See detailThe PseudoDojo: Training and grading a 85 element optimized norm-conserving pseudopotential table
Setten, M. J. Van; Giantomassi, M.; Bousquet, Eric ULiege et al

in Computer Physics Communications (2018)

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See detailCoupling and electrical control of structural, orbital and magnetic orders in perovskites
Varignon, Julien ULiege; Bristowe, Nicholas ULiege; Bousquet, Eric ULiege et al

in Scientific Reports (2015), 5

Perovskite oxides are already widely used in industry and have huge potential for novel device applications thanks to the rich physical behaviour displayed in these materials. The key to the functional ... [more ▼]

Perovskite oxides are already widely used in industry and have huge potential for novel device applications thanks to the rich physical behaviour displayed in these materials. The key to the functional electronic properties exhibited by perovskites is often the so-called Jahn-Teller distortion. For applications, an electrical control of the Jahn-Teller distortions, which is so far out of reach, would therefore be highly desirable. Based on universal symmetry arguments, we determine new lattice mode couplings that can provide exactly this paradigm, and exemplify the effect from firstprinciples calculations. The proposed mechanism is completely general, however for illustrative purposes, we demonstrate the concept on vanadium based perovskites where we reveal an unprecedented orbital ordering and Jahn-Teller induced ferroelectricity. Thanks to the intimate coupling between Jahn-Teller distortions and electronic degrees of freedom, the electric field control of Jahn-Teller distortions is of general relevance and may find broad interest in various functional devices. [less ▲]

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