Dresden 2020 – wissenschaftliches Programm
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TT 35.11: Vortrag
Mittwoch, 18. März 2020, 12:30–12:45, HSZ 304
Magnetodielectric and magnetoelastic coupling in the frustrated fcc antiferromagnet (NH4)2IrCl6 — •Nazir Khan and Alexander A. Tsirlin — Experimental Physics VI, University of Augsburg, 86135 Augsburg, Germany
Magnetodielectric and magnetoelastic phenomena in the fcc antifluorite (NH4)2IrCl6 single crystal have been investigated using thermodynamic, dielectric and magnetostriction measurements. The compound is an antiferromagnetic Mott insulator with the charge gap Δ=0.9 eV and Néel temperature TN=2.2 K. The antiferromagnetic ordering leads to a decrease in temperature-dependent dielectric constant at zero applied field. Further, in the magnetically ordered state the dielectric constant and macroscopic sample length show a strong magnetic field dependence. The dielectric constant increases monotonically with increasing field without any saturation up to a field 14 T where it exhibits a magnetocapacitance of about 0.6%. The magentodielectric phenomenon in the present system is believed to be due to the magnetostrictive effects and spin-phonon coupling. The magnetostrictive effects are evident from the temperature and field dependence of the macroscopic length change. Spin-phonon coupling results when the energy scale of a soft phonon mode associated with the rotation of IrCl6 octahedra becomes comparable with that of a magnetic interaction or magnetic field.
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