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TT: Fachverband Tiefe Temperaturen

TT 69: Correlated Electrons: Spin Systems and Itinerant Magnets - Chiral Magnets

TT 69.3: Vortrag

Mittwoch, 2. April 2014, 15:30–15:45, HSZ 204

Spin chirality flips in transition-metal monogermanides — •Sven-Arne Siegfried¹, Evgeny.V. Altenbayev^2,3, Nadezhda M. Chubova², Vadim Dyadkin^4,2, Evgeny V. Moskvin^2,3, Vladimir Dimitriev⁴, Dirk Menzel⁵, Charles D. Dewhurst⁶, Andre Heinemann¹, Dimitry Chernyshov⁴, Ravil A. Sadykov^7,8, Sergey N. Axenov⁷, Ludmila N. Formicheva⁸, Anatoly V. Tsvyshchenko^8,9, Dieter Lott¹, Andreas Schreyer¹, and Sergey V. Grigoriev^2,3 — ¹Helmholtz-Zentrum Geesthacht, Germany — ²Petersburg Nuclear Physics Institute, Russia — ³Saint-Petersburg State University, Russia — ⁴Swiss Norwegian Beamlines at ESRF, France — ⁵TU Braunschweig, Germany — ⁶Institute Laue-Langevin, France — ⁷Institute for Nuclear Research, Russia — ⁸Institute for High Pressure Physics, Russia — ⁹Moscow State University, Russia

The Mn_1−xFe_xGe compounds are helimagnetically ordered within the full concentration range. Small-angle neutron diffraction measurements show a change of the helical wavevector from | k | = 2.23 nm⁻¹ for pure MnGe passing through a minimum at x ≈ 0.75 (with | k | → 0) to a value of | k | = 0.09 nm⁻¹ for pure FeGe. The helical structure transforms to a ferromagnetic-like one for x → x_c, along with a change of the magnetic chirality for x < x_c and x > x_c. Further studies reveal similar behaviour for Fe_1−xCo_xGe compounds [2]. We argue that this behaviour is caused not by the different signs of the Dzyaloshinskii-Moriya interaction but rather by the complex multi-shell exchange interaction.

[1] S.V. Grigoriev et al.,Phys. Rev. Lett. 110, 207201 (2013)

[2] S.V. Grigoriev et al., to be published.