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arXiv · 1002.1336

Incommensurate spin-density wave and magnetic lock-in transition in CaFe4As3

P. Manuel·L. C. Chapon·I. S. Todorov·D. Y. Chung·J. -P. Castellan·S. Rosenkranz·R. Osborn·P. Toledano·M. G. Kanatzidis
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Abstract

The magnetic structure for the newly discovered iron-arsenide compound \CaFeAs has been studied by neutron powder diffraction. Long-range magnetic order is detected below 85K, with an incommensurate modulation described by the propagation vector k=(0,$\delta$,0), $\delta\sim$ 0.39. Below $\sim$ 25K, our measurements detect a first-order phase transition where $\delta$ locks into the commensurate value 3/8. A model of the magnetic structure is proposed for both temperature regimes, based on Rietveld refinements of the powder data and symmetry considerations. The structures correspond to longitudinal spin-density-waves with magnetic moments directed along the \textit{b}-axis. A Landau analysis captures the change in thermodynamic quantities observed at the two magnetic transitions, in particular the drop in resistivity at the lock-in transition.

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P. Manuel, L. C. Chapon, I. S. Todorov, D. Y. Chung, J. -P. Castellan, S. Rosenkranz, R. Osborn, P. Toledano, M. G. Kanatzidis. 2010-02-05. Incommensurate spin-density wave and magnetic lock-in transition in CaFe4As3. https://doi.org/10.1103/physrevb.81.184402

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