Evolution of helimagnetic correlations when approaching the quantum critical point of Mn1-xFexSi

Evolution of helimagnetic correlations when approaching the quantum critical point of Mn1-xFexSi

Pappas, C. (TU Delft RST/Neutron and Positron Methods in Materials)
Leonov, A.O. (Hiroshima University)
Bannenberg, L.J. (TU Delft RID/TS/Instrumenten groep)
Fouquet, P (Institut Laue-Langevin)
Wolf, T. (Karlsruhe Institut für Technologie)
Weber, F (Karlsruhe Institut für Technologie)

2021-01-08

We present a comprehensive investigation of the evolution of helimagnetic correlations in Mn1−xFexSi with increasing doping. By combining polarized neutron scattering and high resolution neutron spin echo spectroscopy we investigate three samples with x = 0.09, 0.11, and 0.14, i.e., with compositions on both sides of the concentration x∗∼0.11 where the helimagnetic Bragg peaks disappear and between x∗ and the quantum critical concentration xC∼0.17, where TC vanishes. We find that the abrupt disappearance of the long range helical periodicity at x∗ does not affect the precursor fluctuating correlations. These build up with decreasing temperature in a similar way as for the parent compound MnSi. Also the dynamics bears strong similarities to MnSi. The analysis of our results indicates that frustration, possibly due to achiral Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions, increases with increasing Fe doping. We argue that this effect explains both the expansion of the precursor phase with increasing x and the abrupt disappearance of long range helimagnetic periodicity at x∗.

http://resolver.tudelft.nl/uuid:8e7aaafa-04fc-4cb3-80fe-75614017602c

https://doi.org/10.1103/PhysRevResearch.3.013019

2643-1564

Physical Review Research, 3 (1), 1-7

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© 2021 C. Pappas, A.O. Leonov, L.J. Bannenberg, P Fouquet, T. Wolf, F Weber