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Authors
S. Rößler [1], D. Cherian [2], C. Koz [1], Ph. Materne [3], M. Doerr [3], U. K. Rößler [4], Suja Elizabeth [2], H.-H. Klauß[3], U. Schwarz[1], S. Wirth[1] [1] Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, D-01187 Dresden, Germany. [2] Department of Physics, C.V. Raman Avenue, Indian Institute of Science, Bangalore 560012, India. [3] Institut für Festkörperphysik, Technische Universität Dresden, D-01062 Dresden, Germany [4] IFW Dresden, Postfach 270016, D-01171 Dresden, Germany. Recent experiments suggest that Fe1+yTe, the parent compound of the Fe-chalcogenide superconductors, behaves differently than the pnictide counterparts: it exhibits an antiferromagnetic order that is not driven by Fermi surface nesting and a relatively large ordered moment on the Fe sublattices [1, 2]. Here, we show that the magnetic and structural phase transitions are extremely sensitive to such tuning parameters as Fe composition and application of external pressure. Further, for y > 0.12, upon cooling, a continuous magnetic transition takes place at temperatures above the structural transition [3]. In such cases we identify a magnetically inhomogeneous precursor state above the Néel temperature by using Mössbauer spectroscopy. The observed quasi-static moments with short-range correlations can be understood based on a phenomenological Landau theory as a soliton-liquid state that precedes the low-temperature incommensurate helimagnetic phase. This helimagnetic phase undergoes a further magneto-elastic transition at lower temperatures which can be interpreted as a lock-in transition, where the magnetic transformation from the helical into collinear structure drives a structural first-order transition. The succession of the different phases suggests a strong spin-lattice coupling in Fe1+yTe. [1] W. Bao et al., Phys. Rev. Lett. 102, 247001 (2009). [2] E. E. Rodriguez et al., Phys. Rev. B 84, 064403 (2011). [3] S. Rößer et al., Phys. Rev. B 84, 174506 (2011). |
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