Partial ordering and phase elasticity in the MnGe short-period helimagnet

N. Martin 1, * I. Mirebeau 1 C. Franz 2 G. Chaboussant 3 L. Fomicheva 4 N. Fomicheva 4 A. Tsvyashchenko 4
* Corresponding author
3 GIM - Groupe Interfaces et matériaux
LLB - UMR 12 - Laboratoire Léon Brillouin : DRF/IRAMIS/LLB, IRAMIS - Institut Rayonnement Matière de Saclay : DRF/IRAMIS/LLB
Abstract : We study the helimagnetic ground state of the MnGe cubic alloy using small-angle neutron scattering and a high-resolution method, the so-called MIEZE spectroscopy. Upon cooling below the Néel temperature $T_N$ = 170(5) K, we observe the proliferation of long-wavelength $gapless$ spin fluctuations, concomitant with a continuous evolution of the helical correlation length. These fluctuations disappear at $T_{com}$ = 32(5) K when the helical period becomes commensurate with the lattice. We propose to describe this intermediate phase as a soliton lattice, promoting nonlinear collective modes, or $phasons$, over a large temperature interval. We discuss the possible relevance of our results to the previously observed magnetotransport anomalies.
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N. Martin, I. Mirebeau, C. Franz, G. Chaboussant, L. Fomicheva, et al.. Partial ordering and phase elasticity in the MnGe short-period helimagnet. Physical Review B : Condensed matter and materials physics, American Physical Society, 2019, 99, pp.100402. ⟨10.1103/PhysRevB.99.100402⟩. ⟨cea-02074769⟩

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