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Séminaire MCBT : mercredi 23 novembre 2022 à 11h00

Estéfani Marchiori (University of Basel)

Titre : Realspace imaging of magnetic phases in a chiral magnet


Institut Néel, Salle K223
Résumé : The chiral magnet Cu 2 OSeO 3 is a ferroelectric material that exhibits a variety of interesting magnetic phases, including two distinct topological skyrmion spin textures. Skyrmion phases exist at relatively high temperatures of tens of Kelvin because they require thermal fluctuations to become thermodynamically stable in bulk materials. Recently, smallangle neutron scattering measurements (SANS) revealed a second lowtemperature skyrmion phase in Cu 2 OSeO 3 [1,2]. Distinct from the wellknown hightemperature phase, this lowtemperature phase is highly hysteretic and believed to be stabilized by cubic anisotropy. To understand the mixed magnetic phases and the new skyrmion phase in Cu 2 OSeO 3 , we performed magnetic imaging of a bulk single crystal using scanning SQUIDontip microscopy with sub100nm spatial resolution [3]. In this talk, I shall discuss the disordered lowtemperature skyrmion phase, domain formation, and helimagnetic phases observed.

[1] Chacon, A., et al. Nat. Phys. 14, 936 (2018)
[2] Qian, F., et al. Sci. Adv. 4, eaat7323 (2018)
[3] Marchiori, E., et al. Nat. Rev. Phys. 4, 49 (2022)