Electrical-Transport and Magnetodielectric Properties in YMnO₃/La_0.67Sr_0.33MnO₃ Heterostructure

Abstract

In this work, the heterostructure YMnO3/La0.67Sr0.33MnO3 was deposited on SrTiO3(110) substrate by pulsed laser deposition. X-ray diffraction measurements indicated that YMnO3 film consists of coexisting hexagonal phase (h-YMnO3) and orthorhombic phase (o-YMnO3). In the low temperature range from 20 to 200 K, the transport mechanism is dominated by the Schottky emission model. In the high temperature range above 240 K, a space-charge-limited-current behavior is observed under high electric fields. Remarkable magnetoresistivity effects were detected for H = 0.8 T, with MR = −16% near the Néel temperature of o-YMnO3, TN′, and MR = −54% near the Néel temperature of h-YMnO3, TN. At f = 10 kHz, there exist two anomalies of the dielectric constant without an applied magnetic field at about 40 and 80 K, which correspond to the TN′ value of o-YMnO3 and the TN value of h-YMnO3, respectively, demonstrating the coupling between the antiferromagnetic and ferroelectric properties at low temperature. Additionally, the distinct magnetodielectric response of the film originates from the orthorhombic phase rather than the hexagonal phase.