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TT: Fachverband Tiefe Temperaturen

TT 35: Frustrated Magnets - Strong Spin-Orbit Coupling 1 (joint session TT/MA)

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 T_N=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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[2] Jaye K. Harada et al., Phys. Rev. B 93, 104404 (2016)