Magnetic and Optical properties of strained films of multiferroic GdMnO3

TL;DR

This study investigates how strain affects the magnetic and optical properties of GdMnO3 thin films, revealing strain-dependent changes in spin ordering and optical spectra through magnetometry and magneto-optic spectroscopy.

Contribution

It provides new insights into the strain-induced modifications of magnetic and optical behaviors in multiferroic GdMnO3 films using combined spectroscopic and magnetometric techniques.

Findings

Strain influences the spin ordering in GdMnO3 films.

Optical spectra show distinct behavior of charge transfer and band edge transitions under magnetic field.

Neel temperatures and coercive fields vary with strain.

Abstract

The effects of strain on a film of mulitferroic GdMnO3 are investigated using both magnetometry and magneto-optic spectroscopy. Optical spectra, in the energy range 1.5eV - 3.5eV, were taken in Faraday geometry in an applied magnetic field and also at remanence. This yielded rich information on the effects of strain on the spin ordering in these films. Epitaxial films of GdMnO3 were grown on SrTiO3 and LaAlO3 substrates. The LaAlO3 was twinned and so produced a highly strained film whereas the strain was less for the film grown on SrTiO3. The Ne\'el temperatures and coercive fields were measured using zero field data and hysteresis loops obtained using a SQUID magnetometer. Optical absorption data agreed with earlier work on bulk materials. The two well known features in the optical spectrum, the charge transfer transition between Mn d states at ~2eV and the band edge transition from the oxygen p band to the d states at ~3eV are observed in the magnetic circular dichroism; however they behaved very differently both as a function of magnetic field and temperature. This is interpreted in terms of the magnetic ordering of the Mn spins.