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Observation of a new light-induced skyrmion phase in the Mott insulator Cu2OSeO3
Authors:
Alexey A. Sapozhnik,
Benoit Truc,
Phoebe Tengdin,
Emil Viñas Boström,
Thomas Schönenberger,
Simone Gargiulo,
Ivan Madan,
Thomas LaGrange,
Arnaud Magrez,
Claudio Verdozzi,
Angel Rubio,
Henrik M. Rønnow,
Fabrizio Carbone
Abstract:
We report the discovery of a novel skyrmion phase in the multiferroic insulator Cu2OSeO3 for magnetic fields below the equilibrium skyrmion pocket. This phase can be accessed by exciting the sample out of equilibrium with near-infrared (NIR) femtosecond laser pulses but can not be reached by any conventional field cooling protocol. From the strong wavelength dependence of the photocreation process…
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We report the discovery of a novel skyrmion phase in the multiferroic insulator Cu2OSeO3 for magnetic fields below the equilibrium skyrmion pocket. This phase can be accessed by exciting the sample out of equilibrium with near-infrared (NIR) femtosecond laser pulses but can not be reached by any conventional field cooling protocol. From the strong wavelength dependence of the photocreation process and via spin dynamics simulations, we identify the magnetoelastic effect as the most likely photocreation mechanism. This effect results in a transient modification of the magnetic interaction extending the equilibrium skyrmion pocket to lower magnetic fields. Once created, the skyrmions rearrange and remain stable over a long time, reaching minutes. The presented results are relevant for designing high-efficiency non-volatile data storage based on magnetic skyrmions.
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Submitted 15 December, 2022;
originally announced December 2022.
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Ultrafast generation of hidden phases via energy-tuned electronic photoexcitation in magnetite
Authors:
B. Truc,
P. Usai,
F. Pennacchio,
G. Berruto,
R. Claude,
I. Madan,
V. Sala,
T. LaGrange,
G. M. Vanacore,
S. Benhabib,
F. Carbone
Abstract:
Metal-insulator transitions (MIT) occurring in non-adiabatic conditions can evolve through high-energy intermediate states that are difficult to observe and control via static methods. By monitoring the out-of-equilibrium structural dynamics of a magnetite (Fe3O4) crystal via ultrafast electron diffraction, we show that MITs can evolve through different pathways by properly selecting the electroni…
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Metal-insulator transitions (MIT) occurring in non-adiabatic conditions can evolve through high-energy intermediate states that are difficult to observe and control via static methods. By monitoring the out-of-equilibrium structural dynamics of a magnetite (Fe3O4) crystal via ultrafast electron diffraction, we show that MITs can evolve through different pathways by properly selecting the electronic excitation with light. Near-infrared (800 nm) photons inducing d-d electronic transitions is found to favor the destruction of the long-range zigzag network of the trimerons and to generate a phase separation between cubic-metallic and monoclinic-insulating regions. Instead, visible light (400 nm) further promotes the long-range order of the trimerons by stabilizing the charge density wave fluctuations through the excitation of the oxygen 2p to iron 3d charge transfer and, thus, fosters a reinforcement of the monoclinic insulating phase. Our experiments demonstrate that tailored light pulses can drive strongly correlated materials into different hidden phases, influencing the lifetime and emergent properties of the intermediate states.
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Submitted 30 September, 2022;
originally announced October 2022.
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Imaging the ultrafast coherent control of a skyrmion crystal
Authors:
Phoebe Tengdin,
Benoit Truc,
Alexey Sapozhnik,
Lingyao Kong,
Nina del Ser,
Simone Gargiulo,
Ivan Madan,
Thomas Schoenenberger,
Priya R. Baral,
Ping Che,
Arnaud Magrez,
Dirk Grundler,
Henrik M. Rønnow,
Thomas Lagrange,
Jiadong Zang,
Achim Rosch,
Fabrizio Carbone
Abstract:
Exotic magnetic textures emerging from the subtle interplay between thermodynamic and topological fluctuation have attracted intense interest due to their potential applications in spintronic devices. Recent advances in electron microscopy have enabled the imaging of random photo-generated individual skyrmions. However, their deterministic and dynamical manipulation is hampered by the chaotic natu…
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Exotic magnetic textures emerging from the subtle interplay between thermodynamic and topological fluctuation have attracted intense interest due to their potential applications in spintronic devices. Recent advances in electron microscopy have enabled the imaging of random photo-generated individual skyrmions. However, their deterministic and dynamical manipulation is hampered by the chaotic nature of such fluctuations and the intrinsically irreversible switching between different minima in the magnetic energy landscape. Here, we demonstrate a method to coherently control the rotation of a skyrmion crystal by discrete amounts at speeds which are much faster than previously observed. By employing circularly polarized femtosecond laser pulses with an energy below the bandgap of the Mott insulator Cu2OSeO3, we excite a collective magnon mode via the inverse Faraday effect. This triggers coherent magnetic oscillations that directly control the rotation of a skyrmion crystal imaged by cryo-Lorentz Transmission Electron Microscopy. The manipulation of topological order via ultrafast laser pulses shown here can be used to engineer fast spin-based logical devices.
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Submitted 22 July, 2022; v1 submitted 9 October, 2021;
originally announced October 2021.