Neutrons for Science and Industry
# Topological magnetic structures in MnGe: Neutron diffraction and symmetry analysis

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Europe/Berlin

PH HS 3 (Physics Department)

Description

From new neutron powder diffraction experiments on the chiral cubic (*P2 _{1}3*) magnet manganese germanide (MnGe), we analyze all of the possible crystal symmetry-allowed magnetic superstructures [1]. The incommensurate propagation vectors

The magnetic structures in MnGe are compared with topological magnetism in the candidate magnetic Weyl semimetal CeAlGe** ** [2], where the topological properties of a phase stable at intermediate magnetic fields parallel to the *c* axis are suggested by observation of the THE as well. CeAlGe has polar tetragonal *I4 _{1}md* crystal symmetry with the magnetic structure based on two propagation vectors along [100] and [010] axes in tetragonal plane with periodicity about 70 Å. The multi-

Both 3+2 structures in MnGe and CeAlGe host lattices of magnetic particle-like objects called (anti)merons *Q*=±1/2 with half-integer topological numbers. Calculations show that in the external magnetic fields perpendicular to the propagation plane the total charge per magnetic cell abruptly changes from *Q*=0 to skyrmion-like charge *|Q|*=1 in accordance with is the experimental observation of the THE in the same field range.

[1] V. Pomjakushin, I. Plokhikh, J. S. White, Y. Fujishiro, N. Kanazawa, Y. Tokura, and E. Pomjakushina, Phys. Rev. B **107**, 024410 (2023)

[2] P. Puphal, V. Pomjakushin, N. Kanazawa, V. Ukleev, D. J. Gawryluk, J. Ma, M. Naamneh, N. C. Plumb, L. Keller, R. Cubitt, E. Pomjakushina, and J. S. White, Phys. Rev. Lett. **124**, 017202 (2020)

Organized by

Dr. Theresia Heiden-Hecht

Dr. Jitae Park

Videoconference