| AVS 58th Annual International Symposium and Exhibition | |
| Magnetic Interfaces and Nanostructures Division | Thursday Sessions |
| Session MI-ThM |
| Session: | Emerging Magnetic Characterization and Results |
| Presenter: | Ju Choi, University of California Los Angeles |
| Authors: | J.H. Choi, University of California Los Angeles T.E. Quickel, University of California Los Angeles S. Tolbert, University of California Los Angeles J.P. Chang, University of California Los Angeles |
| Correspondent: | Click to Email |
Multiferroic materials induced polarization under external magnetic field H, or induced magnetization under external electric field E. Magnetoelectric (ME) phenomena in multiferroic materials holds considerable promises because of their potential applications in spintronics, such as magneto-electric sensors, magneto-capacitive devices, and electrically driven magnetic data storage. The ultimate goal for practical device application of multiferroic materials is dependent on how to create strong ME coupling between different types of ferroic order. The strictive interaction between the piezoelectricity of the ferroelectric (FE) phase and the magnetostriction of the ferromagnetic (FM) phase lead to produce larger ME coefficients than single phase multiferroic materials. Thus, the research has been directed towards designing engineered multiferroic composite materials in the form of horizontal multilayer (2-2), vertical superstructures (3-1) or other nanoparticle composite structures (3-0) in a precise controlled manner.
In this work, the BiFeO3 (BFO) and Pb(ZrTi)O3 (PZT) thin film were synthesized by radical enhanced atomic layer deposition (RE-ALD). RE-ALD is a gas-phase technique in which precursor vapors are pulsed alternately into the reaction chamber and the thin film growth proceeds through surface reactions in a self limiting manner. The advantages of ALD include excellent conformality, simple and accurate thickness control and good uniformity on large areas. In order to demonstrate conformal deposition of engineered multiferroic materials in the form of 3-0 or 2-2 configuration, PZT and BFO was deposited onto a mesoporous CoFe2O4 (CFO) substrate by RE-ALD.
The mesoporous CFO films were found to be fully filled by ALD PZT and BFO. The composition and crystal structure of the PZT-CFO and BFO-CFO systems were confirmed by X-ray Photon Spectroscopy and X-ray Diffraction (XRD), respectively. More detail crystal structure were investigated by synchrotron XRD and extended x-ray absorption fine structure spectroscopy (EXAFS). The magnetic and ferroelectric properties for the PZT-CFO or BFO-CFO systems were characterized by a superconducting quantum interference device (SQUID) magnetometer and piezoresponse force microscopy (PFM). Magnetic properties such as coercive magnetic field (Hc) and saturation moment (Ms) were systematically analyzed on composite systems and the pure CFO substrate. In addition, The P-E loops for PZT-CFO and BFO-CFO thin films were measured at room temperature and the saturation polarization (Ps) and coercive field (Ec) were investigated with respect to thickness and crystal plan.