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Confinement-controlled pathways to complex skyrmionic textures in Co/W/Pt multilayers
Authors:
Y. Al Sadi,
R. Sbiaa,
W. Al Saidi,
M. Souier,
G. Lezier,
O. Marbouh,
M. T. Z. Myint,
Y. Dusch,
S. Al Harthi,
A. Talbi,
N. Tiercelin,
S. N. Piramanayagam
Abstract:
Magnetic skyrmions and higher-order topological spin textures offer rich opportunities for multi-level information encoding, yet their deterministic stabilization and transformation under geometric confinement at room temperature remain poorly understood. Here, we demonstrate that geometric confinement acts as a robust and universal control parameter that governs a hierarchical transformation path…
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Magnetic skyrmions and higher-order topological spin textures offer rich opportunities for multi-level information encoding, yet their deterministic stabilization and transformation under geometric confinement at room temperature remain poorly understood. Here, we demonstrate that geometric confinement acts as a robust and universal control parameter that governs a hierarchical transformation pathway of chiral spin textures in Pt/Co/W multilayer micro-tracks. As the confinement increases, extended labyrinth domains fragment into isolated skyrmions, followed by the systematic suppression of skyrmion pairs and the preferential stabilization of compact higher-order textures. We find that confinement strongly enhances the formation of skyrmioniums via recombination and promotes their subsequent evolution into uniform skyrmion bags by capturing additional skyrmions. Statistical analysis reveals a confinement-driven redistribution of topological populations, with skyrmion bags emerging as the dominant state in the narrowest tracks. Supported by micromagnetic simulations, our results establish geometric confinement as a deterministic selector of complex topological textures and reveal a previously unexplored route for engineering higher-order skyrmionic states at room temperature. These findings provide a scalable materials strategy for multistate skyrmion-based spintronic and memory architectures.
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Submitted 15 April, 2026;
originally announced April 2026.
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Microfabricated multi-axis cell for integrated atomic devices
Authors:
L. Péroux,
A. Dewilde,
A. Mursa,
A. Mazzamurro,
J. Bonhomme,
Q. Tanguy,
E. Klinger,
L. Gauthier-Manuel,
O. Gaiffe,
A. Talbi,
R. Boudot,
P. Pernod,
J. -F. Clément,
V. Maurice,
N. Passilly
Abstract:
Microfabricated alkali vapor cells enable the miniaturization of atomic sensors, but require collective wafer-level integration of complex features. In many applications, including magnetometers, gyroscopes, magneto-optical traps, and fluorescence imaging, multiple optical accesses are needed to enhance performance. Yet, achieving this without compromising manufacturability remains challenging. In…
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Microfabricated alkali vapor cells enable the miniaturization of atomic sensors, but require collective wafer-level integration of complex features. In many applications, including magnetometers, gyroscopes, magneto-optical traps, and fluorescence imaging, multiple optical accesses are needed to enhance performance. Yet, achieving this without compromising manufacturability remains challenging. In this work, we present a wafer-level fabrication approach that enables three orthogonal optical pathways in microfabricated alkali vapor cells, using fully scalable and collective processes. Our method relies on the thermal reflow of glass preforms, shaped by laser-assisted etching (LAE) and bonded between silicon frames. The relatively low surface roughness produced by LAE allows effective reflow, which further smooths the surfaces without significantly compromising the optical planarity of the windows. This process results in multi-axis vapor cells featuring embedded, optics-grade lateral windows. We evaluate the device performance through both single-beam and dual-beam atomic magnetometry measurements. Magnetic sensitivities better than 200 fT/sqrt(Hz) are demonstrated along each of the three orthogonal axes, confirming the potential of the approach for tri-axis magnetic field sensing at sub-picotesla resolution. This fabrication strategy opens new perspectives for versatile, high-performance atomic sensors, fully compatible with wafer-level integration and mass production.
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Submitted 26 September, 2025;
originally announced September 2025.
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Locally-sealed microfabricated vapor cells filled from an ex situ Cs source
Authors:
L. Péroux,
A. Dewilde,
R. Chutani,
A. Mazzamurro,
J. Bonhomme,
A. Mursa,
J. -F. Clément,
A. Talbi,
P. Pernod,
N. Passilly,
V. Maurice
Abstract:
Microfabricated alkali vapor cells are key to enable miniature devices such as atomic clocks and optically pumped magnetometers with reduced size, weight and power. Yet, more versatile fabrication methods are still needed to further expand their use cases. Here, we demonstrate a novel approach to collectively fill and seal microfabricated cesium cells using locally-sealed microchannels patterned w…
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Microfabricated alkali vapor cells are key to enable miniature devices such as atomic clocks and optically pumped magnetometers with reduced size, weight and power. Yet, more versatile fabrication methods are still needed to further expand their use cases. Here, we demonstrate a novel approach to collectively fill and seal microfabricated cesium cells using locally-sealed microchannels patterned within one of the glass substrates comprising the cells. Unlike current methods that rely on wafer-level anodic bonding as the last sealing step, an approach based on local sealing opens the path to features so far limited to traditional glass-blown cells, including the ability to deposit temperature-sensitive antirelaxation coatings, reaching lower background gas pressure without an additional gettering material or filling with diverse atomic or molecular species.
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Submitted 15 February, 2025;
originally announced February 2025.
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Flow separation control design with experimental validation
Authors:
T. Arnoult,
G. Acher,
V. Nowinski,
P. Vuillemin,
C. Briat,
P. Pernod,
C. Ghouila-Houri,
A. Talbi,
E. Garnier,
C. Poussot-Vassal
Abstract:
Flow control aims at modifying a natural flow state to reach an other flow state considered as advantageous. In this paper, active feedback flow separation control is investigated with two different closed-loop control strategies, involving a reference signal tracking architecture. Firstly, a data-driven control law, leading to a linear (integral) controller is employed. Secondly, a phenomenologic…
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Flow control aims at modifying a natural flow state to reach an other flow state considered as advantageous. In this paper, active feedback flow separation control is investigated with two different closed-loop control strategies, involving a reference signal tracking architecture. Firstly, a data-driven control law, leading to a linear (integral) controller is employed. Secondly, a phenomenological/model-driven approach, leading to a non-linear positive (integral) control strategy is investigated. While the former benefits of a tuning simplicity, the latter prevents undesirable effects and formally guarantees closed-loop stability. Both control approaches were validated through wind tunnel experiments of flow separation over a movable NACA 4412 plain flap. These control laws were designed with respect to hot film measurements, performed over the flap for different deflection angles. Both control approaches proved efficient in avoiding flow separation. The main contribution of this work is to provide practitioners simple but yet efficient ways to design a flow separation controller. In addition, a complete validation campaign data-set is provided.
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Submitted 21 September, 2023;
originally announced September 2023.
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Giant magnetoelastic coupling in Love acoustic waveguide based on uniaxial multilayered TbCo2/FeCo nanostructured thin film on Quartz ST-cut
Authors:
Aurelien Mazzamurro,
Yannick Dusch,
Philippe Pernod,
Olivier Bou Matar,
Ahmed Addad,
Abdelkrim Talbi,
Nicolas Tiercelin
Abstract:
Coupling between dynamic strain and magnetization in ferromagnetic thin films has attracted special consideration as it presents both intriguing fundamental physics problems and technological importance for potential multi-functional devices and information handling. The dynamic strain can be generated by acoustic waves including bulk, surface or guided waves. In this work, we propose the theoreti…
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Coupling between dynamic strain and magnetization in ferromagnetic thin films has attracted special consideration as it presents both intriguing fundamental physics problems and technological importance for potential multi-functional devices and information handling. The dynamic strain can be generated by acoustic waves including bulk, surface or guided waves. In this work, we propose the theoretical and experimental investigation of the interaction of pure shear horizontal (SH) wave with a uniaxial multilayered TbCo2/FeCo thin film in a delay line configuration fabricated on Quartz ST-90X cut. We evaluate theoretically the evolution of phase velocity as a function of magnetic field and experimentally the variation of the transmission coefficient. A piezomagnetic model was developed allowing us to calculate the elastic stiffness constants of the multilayer as a function of the applied magnetic field. The model was also implemented for acoustic waves dispersion curves calculation. We show that the evolution of phase velocity is dominated by the C66 elastic stiffness constant variation as expected for the case of shear horizontal surface wave. The fabricated device let us exciting both fundamental and third harmonic shear mode at 410 MHz and 1.2 GHz, respectively. For both modes, the theoretical results corroborate very well the experimental ones. At 1.2 GHz the mode exhibits a maximum phase velocity shift close to 2.5% and an attenuation reaching 500 dB/cm, for a sensitivity as high as 250 ppm/Oe. The reported theoretical model and experimental results are of tremendous interest for the development of advanced devices for magnetic field sensing applications as well as investigating magnon-phonon interaction at a fundamental level.
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Submitted 22 January, 2020; v1 submitted 2 August, 2019;
originally announced August 2019.
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Autler-Townes splitting and acoustically induced transparency based on Love waves interacting with pillared meta-surface
Authors:
Yuxin Liu,
Abdelkrim Talbi,
El Houssaine El Boudouti,
Olivier Bou Matar,
Philippe Pernod,
Bahram Djafari-Rouhani
Abstract:
Autler-Townes Splitting (ATS) and Electromagnetically Induced Transparency (EIT) are similar phenomena but distinct in nature. They have been widely discussed and distinguished by employing the Akaike information criterion (AIC). However, such work is lacking in acoustic system. In this work, the interaction of Love waves with two-line pillared meta-surface is numerically investigated by Finite El…
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Autler-Townes Splitting (ATS) and Electromagnetically Induced Transparency (EIT) are similar phenomena but distinct in nature. They have been widely discussed and distinguished by employing the Akaike information criterion (AIC). However, such work is lacking in acoustic system. In this work, the interaction of Love waves with two-line pillared meta-surface is numerically investigated by Finite Element Method. Acoustic analogue of ATS, Fabry-Perot resonance and cavity modes are first demonstrated in two lines of identical pillars by varying the distance between the pillar lines. By detuning the radius of one line of pillars, Fabry-Perot resonance along with two different pillar resonances give rise to the acoustic analogue of EIT (AIT) when the distance between the pillar lines is a multiple of half wavelength. ATS and AIT formula models are used to fit the transmission spectra, showing good agreements with numerical results. The quality of the fit models is quantitatively evaluated by resorting to the AIC. We show that theoretical and analytical discrimination between ATS and AIT are methodologically complementary. These results should have important consequences for potential acoustic applications such as wave control, designing of meta-materials and bio-sensors.
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Submitted 29 May, 2019; v1 submitted 11 March, 2019;
originally announced March 2019.
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Interaction of Love waves with coupled cavity modes in a 2D holey phononic crystal
Authors:
Yuxin Liu,
Abdelkrim Talbi,
Bahram Djafari-Rouhani,
El Houssaine El Boudouti,
Lucie Drbohlavova,
Vincent Mortet,
Olivier Bou Matar,
Philippe Pernod
Abstract:
The interaction of Love waves with square array of pillars deposited on a cavity defined in a 2D holey phononic crystal is numerically investigated using Finite Element Method. First, the existence of SH surface modes is demonstrated separately for phononic crystals that consist of square arrayed holes, or rectangular arrayed Ni pillars, respectively in, or on, a SiO2 film deposited on a ST-cut qu…
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The interaction of Love waves with square array of pillars deposited on a cavity defined in a 2D holey phononic crystal is numerically investigated using Finite Element Method. First, the existence of SH surface modes is demonstrated separately for phononic crystals that consist of square arrayed holes, or rectangular arrayed Ni pillars, respectively in, or on, a SiO2 film deposited on a ST-cut quartz substrate. The coupling between SH modes and torsional mode in pillars induces a transmission dip that occurs at a frequency located in the range of the band-gap of the holey phononic crystal. Second, a cavity is constructed by removing lines of holes in the holey phononic crystal and results in a transmission peak that matches the dip. The optimal geometrical parameters enable us to create a coupling of the cavity mode and the localized pillar mode by introducing lines of pillars into the cavity, which significantly improved the efficiency of the cavity without increasing the crystal size. The obtained results will pave the way to implement advanced designs of high-performance electroacoustic sensors based on coupling modes in phononic crystals.
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Submitted 2 March, 2019; v1 submitted 9 November, 2018;
originally announced November 2018.
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Highly confined Love waves modes by defect states in a holey SiO2 /quartz phononic crystal
Authors:
Yuxin Liu,
Abdelkrim Talbi,
Philippe Pernod,
Olivier Matar
Abstract:
Highly confined Love modes are demonstrated in a phononic crystal based on a square array of etched holes in SiO 2 deposited on the ST-cut quartz. An optimal choice of the geometrical parameters contributes to a wide stop-band for shear waves' modes. The introduction of a defect by removing lines of holes leads to the nearly flat modes within the band gap and consequently paves the way to implemen…
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Highly confined Love modes are demonstrated in a phononic crystal based on a square array of etched holes in SiO 2 deposited on the ST-cut quartz. An optimal choice of the geometrical parameters contributes to a wide stop-band for shear waves' modes. The introduction of a defect by removing lines of holes leads to the nearly flat modes within the band gap and consequently paves the way to implement advanced designs of electroacoustic filters and high-performance cavity resonators. The calculations are based on the finite element method in considering the elastic and piezoelectric properties of the materials. Interdigital transducers are employed to measure the transmission spectra. The geometrical parameters enabling the appearance of confined cavity modes within the band gap and the efficiency of the electric excitation were investigated.
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Submitted 1 October, 2018;
originally announced October 2018.