THz and infrared studies of multiferroic hexagonal Y_(1-x)Eu_xMnO_3 (x=0 - 0.2) ceramics

Abstract

We report an investigation of hexagonal Y_(1-x)Eu_xMnO_3 ceramics with x=0, 0.1 and 0.2 using infrared and THz spectroscopies in the temperature range between 5 and 900 K. The temperature dependence of the THz permittivity reveals a kink near the antiferromagnetic phase transition temperature T_N ~ 70 K giving evidence of a strong spin-lattice coupling. Below T_N two absorption peaks were revealed in the THz spectra close to 43 and 73 cm-1. While the first peak corresponds to a sharp antiferromagnetic resonance exhibiting softening on heating towards TN, the second one may be attributed to an impurity mode or a multiphonon absorption peak. High-temperature THz spectra measured up to 900 K reveal only small gradual increase of the permittivity in agreement with a weak phonon softening observed in the infrared reflectance spectra upon heating. This corresponds to an improper ferroelectric character of the phase transition proposed from first principle calculations by Fennie and Rabe [Phys. Rev. B 72 (2005), pp. 100103(R)].

Phase Transitions, accepted

References in corpus (3)

• The ferroelectric transition in YMnO${}_3$ from first principles
• Unconventional spin fluctuations in the hexagonal antiferromagnet YMnO${}_3$
• Experimental evidence for an intermediate phase in the multiferroic YMnO3

Cited by in corpus (6)

• Hexagonal RMnO${}_3$: a model system for 2D triangular lattice antiferromagnets
• Terahertz and infrared spectroscopic evidence of phonon-paramagnon coupling in hexagonal piezomagnetic YMnO3
• Magnons and crystal field transitions in hexagonal REMnO3 (RE = Er, Tm, Yb, Lu) single crystals
• Unusual ferroelectric and magnetic phases in multiferroic 2H-BaMnO${}_3$ ceramics
• h-ErMnO3 absorbance, reflectivity and, emissivity in the THz to mid-infrared from 2 K to 1700 K: carrier screening, Fröhlich resonance, small polarons, and bipolarons
• Far- and Mid-infrared Emission and Reflectivity of Orthorhombic and Cubic ErMnO3: polarons and bipolarons