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Long-period helical structures and twist-grain boundary phases induced by chemical substitution in the Mn$_{1−x}$ (Co, Rh)$_x$ Ge chiral magnet

N. Martin 1, 2 Maxime Deutsch 3 G. Chaboussant 4, 2 F. Damay 2, 1 P. Bonville 5 L. Fomicheva 6 A. Tsvyashchenko 6, 7 U. Rössler 8 I. Mirebeau 2, 1
1 GDP - Groupe Diffraction Poudres
LLB - UMR 12 - Laboratoire Léon Brillouin : DRF/IRAMIS/LLB, IRAMIS - Institut Rayonnement Matière de Saclay : DRF/IRAMIS/LLB
4 GIM - Groupe Interfaces et matériaux
IRAMIS - Institut Rayonnement Matière de Saclay : DRF/IRAMIS/LLB, LLB - UMR 12 - Laboratoire Léon Brillouin : DRF/IRAMIS/LLB
5 LNO - Laboratoire Nano-Magnétisme et Oxydes
SPEC - UMR3680 - Service de physique de l'état condensé, IRAMIS - Institut Rayonnement Matière de Saclay
Abstract : We study the evolution of helical magnetism in MnGe chiral magnet upon partial substitution of Mn for 3$d$-Co and 4$d$-Rh ions. At high doping levels, we observe spin helices with very long periods—more than ten times larger than in the pure compound—and sizable ordered moments. This behavior calls for a change in the energy balance of interactions leading to the stabilization of the observed magnetic structures. Strikingly, neutron scattering unambiguously shows a double periodicity in the observed spectra at x=0.5 and >0.2 for Co- and Rh-doping, respectively. In analogy with observations made in smectic liquid crystals, we suggest that it may reveal the presence of magnetic “twist grain boundary” phases, involving a dense short-range correlated network of magnetic screw dislocations. The dislocation cores are here tentatively described as smooth textures, made of nonradial double-core skyrmions.
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https://hal.univ-lorraine.fr/hal-01709628
Contributor : Maxime Deutsch <>
Submitted on : Thursday, February 15, 2018 - 10:41:34 AM
Last modification on : Friday, March 5, 2021 - 3:11:17 PM

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N. Martin, Maxime Deutsch, G. Chaboussant, F. Damay, P. Bonville, et al.. Long-period helical structures and twist-grain boundary phases induced by chemical substitution in the Mn$_{1−x}$ (Co, Rh)$_x$ Ge chiral magnet. Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 2017, 96, pp.020413(R). ⟨10.1103/PhysRevB.96.020413⟩. ⟨hal-01709628⟩

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