(07D909) Magnetic and dielectric properties of layered perovskite Gd_2Ti_2O_7 thin film epitaxially stabilized on a perovskite single crystal

摘要

Layered perovskite (LP) titanates, Ln_2Ti_2O_7 (Ln = lanthanoids), are ferroelectric materials containing magnetic Ln~(3+) ions at A-site. Metastable LP-Gd_2Ti_2O_7 was fabricated in epitaxial thin film form on lattice-matched perovskite substrates and its dielectric and magnetic properties were investigated. The (100)-oriented LP-Gd_2Ti_2O_7 films were epitaxially grown on (110) plane of (LaAlO_3)_(0.3)-(SrAl_(0.5)Ta_(0.5)O_3)_(0.7) (LSAT) and Nb-doped SrTiO_3 by using a pulsed laser deposition method. Piezoresponse force microscope measurements revealed that LP-Gd_2Ti_2O_7 has spontaneous polarization along the b-axis at room temperature, strongly suggesting room temperature ferroelectricity. Magnetization measurements showed paramagnetic behavior with weak antiferromagnetic interaction around 2K. Small positive magneto-dielectric effect (Δε/ε~ 10~(-5) order) was also confirmed at 10 K.