Confirmation of spatial coexistence of magneto-electric coupling in Bi 0.7Dy 0.3FeO 3 thin films integrated with Si/ZnO film for MEMS and memory applications

摘要

Spatial presence of ferroelectric and magnetic domain structure of the multiferroic dysprosium (Dy)-modified BiFeO3(Bi0.7Dy0.3FeO3or BDFO) deposited on ZnO at the macroscopic level is investigated in this paper. BDFO thin film is deposited on Si/ZnO using pulsed laser deposition (PLD) technique. Magnetic properties are observed by saturated magnetic hysteresis at room temperature. Ferroelectric hysteresis loop (P–E) is used to compare the response of magnetic field on ferroelectric properties at room temperature of BDFO and BDFO/ZnO thin films. The changes in ferroelectric hysteresis loops with magnetic field ensures about the magnetoelectric (M–E) coupling in BDFO/ZnO films. A well-saturated ferroelectric hysteresis loop with remarkable improvement in remanent polarization (～1.72μC/cm2) is observed. The obtained results confirm the coexistence of ferromagnetic and ferroelectric ordering with significant coupling at room temperature. The coupling behavior and magnetic transition are also verified using multimode atomic force microscope by applying bias between sample and MFM tip. The leakage current density is measured in the order of 10?5A/cm2. Integration of BDFO films with ZnO piezoelectric thin film suggests in principle its potential in applications of micro electro mechanical systems (MEMS) as well as in memory devices and in strong history dependent systems.