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Close Correlation between Magnetic Properties and the Soft Phonon Mode of the Structural Transition in BaFe2A s2 and SrFe2As2

Published

Author(s)

Daniel E Parshall, L. Pintschovius, J. L. Niedziela, J.-P. Castellan, D. Lamago, R. Mittal, Th. Wolf, D. Reznik

Abstract

Parent compounds of Fe-based superconductors undergo a structural phase transition from a tetragonal to an orthorhombic structure. We investigated the temperature dependence of the frequencies of transverse acoustic (TA) phonons that extrapolate to the shear vibrational mode at the zone center, which corresponds to the orthorhombic deformation of the crystal structure at low temperatures in BaFe2As2 and SrFe2As2. We found that acoustic phonons at small wavevectors soften gradually towards the transition from high temperatures, tracking the increase of the size of slowly fluctuation magnetic domains. On cooling below the transition to base temperature the phonons harden, following the square of the magnetic moment (which we find is proportional to the anisotropy gap). Our results provide evidence for close correlation between magnetic and phonon properties in Fe-based superconductors.
Citation
Physical Review B
Volume
91
Issue
13

Keywords

phonon, ferropnictide, magnetoelastic coupling

Citation

, D. , Pintschovius, L. , , J. , Castellan, J. , Lamago, D. , Mittal, R. , Wolf, T. and Reznik, D. (2015), Close Correlation between Magnetic Properties and the Soft Phonon Mode of the Structural Transition in BaFe<sub>2</sub>A s<sub>2</sub> and SrFe<sub>2</sub>As<sub>2</sub>, Physical Review B, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=918242 (Accessed April 14, 2024)
Created April 27, 2015, Updated February 19, 2017