Long-period helical structures and twist-grain boundary phases induced by chemical substitution in the Mn$_{1−x}$ (Co, Rh)$_x$ Ge chiral magnet - Université de Lorraine
Journal Articles Physical Review B: Condensed Matter and Materials Physics (1998-2015) Year : 2017

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

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.

Domains

Cristallography

Dates and versions

hal-01709628 , version 1 (15-02-2018)

Identifiers

Cite

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), 2017, 96, pp.020413(R). ⟨10.1103/PhysRevB.96.020413⟩. ⟨hal-01709628⟩
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