| 1. |
- Langlois, M., et al.
(författare)
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First scattered light detection of a nearly edge-on transition disk around the T Tauri star RY Lupi
- 2018
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 614
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Tidskriftsartikel (refereegranskat)abstract
- Context. Transition disks are considered sites of ongoing planet formation, and their dust and gas distributions could be signposts of embedded planets. The transition disk around the T Tauri star RY Lup has an inner dust cavity and displays a strong silicate emission feature. Aims. Using high-resolution imaging we study the disk geometry, including non-axisymmetric features, and its surface dust grain, to gain a better understanding of the disk evolutionary process. Moreover, we search for companion candidates, possibly connected to the disk. Methods. We obtained high-contrast and high angular resolution data in the near-infrared with the VLT/SPHERE extreme adaptive optics instrument whose goal is to study the planet formation by detecting and characterizing these planets and their formation environments through direct imaging. We performed polarimetric imaging of the RY Lup disk with IRDIS (at 1.6 mu m), and obtained intensity images with the IRDIS dual-band imaging camera simultaneously with the IFS spectro-imager (0.9-1.3 mu m). Results. We resolved for the first time the scattered light from the nearly edge-on circumstellar disk around RY Lup, at projected separations in the 100 au range. The shape of the disk and its sharp features are clearly detectable at wavelengths ranging from 0.9 to 1.6 mu m. We show that the observed morphology can be interpreted as spiral arms in the disk. This interpretation is supported by in-depth numerical simulations. We also demonstrate that these features can be produced by one planet interacting with the disk. We also detect several point sources which are classified as probable background objects.
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| 2. |
- Bommanaboyena, S. P., et al.
(författare)
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Readout of an antiferromagnetic spintronics system by strong exchange coupling of Mn2Au and Permalloy
- 2021
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- In antiferromagnetic spintronics, the read-out of the staggered magnetization or Néel vector is the key obstacle to harnessing the ultra-fast dynamics and stability of antiferromagnets for novel devices. Here, we demonstrate strong exchange coupling of Mn2Au, a unique metallic antiferromagnet that exhibits Néel spin-orbit torques, with thin ferromagnetic Permalloy layers. This allows us to benefit from the well-established read-out methods of ferromagnets, while the essential advantages of antiferromagnetic spintronics are only slightly diminished. We show one-to-one imprinting of the antiferromagnetic on the ferromagnetic domain pattern. Conversely, alignment of the Permalloy magnetization reorients the Mn2Au Néel vector, an effect, which can be restricted to large magnetic fields by tuning the ferromagnetic layer thickness. To understand the origin of the strong coupling, we carry out high resolution electron microscopy imaging and we find that our growth yields an interface with a well-defined morphology that leads to the strong exchange coupling.
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| 3. |
- Jourdan, M., et al.
(författare)
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Writing information by current pulses in antiferromagnetic Mn2Au
- 2023
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Ingår i: 2023 IEEE International Magnetic Conference - Short Papers, INTERMAG Short Papers 2023 - Proceedings. - 9798350338362
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Konferensbidrag (refereegranskat)abstract
- Antiferromagnets (AFMs) are promising for future spintronic applications because of their fast dynamics and lack of stray fields. For the required switching of the Néel vector (staggered magnetization), a current induced bulk Néel spin-orbit torque (NSOT) is most promising. Here we demonstrate current pulse induced complete, remanent, and reversible Néel vector switching of epitaxial Mn2Au(001) thin films. A current polarity dependence demonstrates an NSOT acting on AFM domain walls. We correlate direct imaging of the Néel vector reorientation by x-ray photoemission electron microscopy with measurements of the associated anisotropic magnetoresistance [1].
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| 4. |
- Reimers, S., et al.
(författare)
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Current-driven writing process in antiferromagnetic Mn2Au for memory applications
- 2023
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Ingår i: Nature Communications. - 2041-1723. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Current pulse driven Néel vector rotation in metallic antiferromagnets is one of the most promising concepts in antiferromagnetic spintronics. We show microscopically that the Néel vector of epitaxial thin films of the prototypical compound Mn2Au can be reoriented reversibly in the complete area of cross shaped device structures using single current pulses. The resulting domain pattern with aligned staggered magnetization is long term stable enabling memory applications. We achieve this switching with low heating of ≈20 K, which is promising regarding fast and efficient devices without the need for thermal activation. Current polarity dependent reversible domain wall motion demonstrates a Néel spin-orbit torque acting on the domain walls.
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