Influence of Concentration Fluctuations on Relaxation Processes in Spin Glasses
1
Physik-Department E21, Technische Universität München, 85747 Garching, Germany
2
Heinz-Maier-Leibnitz-Zentrum (MLZ), Technische Universität München, Lichtenbergstr. 1, 85748 Garching, Germany
3
Institute for Materials Science, University of Stuttgart, Heisenbergstr. 3, 70569 Stuttgart, Germany
4
Karlsruhe Institute for Technology, KNMF and IAM-WK, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
5
Forschungszentrum Jülich GmbH, JCNS Outstation at MLZ, Lichtenbergstr. 1, 85747 Garching, Germany
6
Brookhaven National Laboratory, Department of Physics, Upton, NY 11973, USA
*
Author to whom correspondence should be addressed.
Quantum Beam Sci. 2018, 2(4), 26; https://doi.org/10.3390/qubs2040026
Received: 21 June 2018 / Revised: 20 November 2018 / Accepted: 21 November 2018 / Published: 28 November 2018
(This article belongs to the Special Issue Magnetic Materials and Magnetism)
Using the unique combination of atomically resolved atom probe tomography (APT) and volume averaged neutron (resonance) spin echo (NRSE and NSE) experiments, the influence of nano-scaled clusters on the spin relaxation in spin glasses was studied. For this purpose, the phase transition from the paramagnetic phase to the spin glass phase in an Fe-Cr spin glass with a composition of Fe Cr was studied in detail by means of NRSE. The microstructure was characterised by APT measurements, which show local concentration fluctuations of Fe and Cr on a length scale of 2 to 5 nm, which lead (i) to the coexistence of ferro- and anti-ferromagnetic clusters and (ii) a change of the magnetic properties of the whole sample, even in the spin glass phase, where spins are supposed to be randomly frozen. We show that a generalized spin glass relaxation function, which was successfully used to describe the phase transition in diluted spin glasses, can also be used for fitting the spin dynamics in spin glasses with significant concentration fluctuations.
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Keywords:
spin glasses; disordered systems; magnetism; neutron spin echo
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MDPI and ACS Style
Wagner, J.N.; Häußler, W.; Holderer, O.; Bauer, A.; Shapiro, S.M.; Böni, P. Influence of Concentration Fluctuations on Relaxation Processes in Spin Glasses. Quantum Beam Sci. 2018, 2, 26.
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