Low temperature incommensurately modulated and noncollinear spin structure in FeCr2S4

FeCr2S4 orders magnetically at T-N approximate to 170 K. According to neutron diffraction, the ordered state down to 4.2 K is a simple collinear ferrimagnet maintaining the cubic spinel structure. Later studies, however, claimed trigonal distortions below similar to 60 K coupled to the formation of a spin glass type ground state. To obtain further insight, muon spin rotation/relaxation (mu SR) spectroscopy was carried out between 5 and 200 K together with new Fe-57 Mossbauer measurements. Below similar to 50 K, our data point to the formation of an incommensurately modulated noncollinear spin arrangement like a helical spin structure. Above 50 K, the spectra are compatible with collinear ferrimagnetism, albeit with a substantial spin disorder on the scale of a few lattice constants. These spin lattice distortions become very large at 150 K and the magnetic state is now better characterized as consisting of rapidly fluctuating short-range ordered spins. The Neel transition is of second order, but ill defined, extending over a range of similar to 10 K. The Mossbauer data around 10 K confirm the onset of orbital freezing and are also compatible with the noncollinear order of iron. The absence of a major change in the quadrupole interaction around 50 K renders the distortion of crystal symmetry to be small.

Krimmel, A. (author)
Hartmann, OlaUppsala universitet,Institutionen för fysik och materialvetenskap(Swepub:uu)oha30325 (author)
Wäppling, RogerUppsala universitet,Institutionen för fysik och materialvetenskap (author)
Wagner, F. E. (author)
Litterst, F. J. (author)
Tsurkan, V. (author)
Loidl, A. (author)
Uppsala universitetInstitutionen för fysik och materialvetenskap (creator_code:org_t)

By the author/editor: Kalvius, G. M.; Krimmel, A.; Hartmann, Ola; Wäppling, Roger; Wagner, F. E.; Litterst, F. J.; show more...; Tsurkan, V.; Loidl, A.; show less...

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