Experimental Methods
This chapter introduces some relevant technologies and experimental methods used in the investigation of electrical control of magnetization. It mainly includes the sample preparation techniques: pulsed laser deposition and magnetron sputtering; the sampl
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Experimental Methods
This chapter will introduce the relevant technologies and experimental methods employed for the work of the thesis. It mainly includes the sample preparation techniques: pulsed laser deposition (PLD) and magnetron sputtering; the sample measurement and characterization techniques: (i) the experimental methods used to characterize the macroscopic magnetic properties of the samples, including the superconducting quantum interference device (SQUID), electron spin resonance (ESR), magneto-optical Kerr effect (MOKE) techniques; (ii) the experimental methods used to characterize the macroscopic ferroelectric and piezoelectric properties of the samples, including ferroelectric hysteresis loops and strain curves measurement techniques; (iii) the experimental methods used to characterize the microscopic magnetic and ferroelectric properties, including scanning probe microscopy (SPM), X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques; and the electric transport measurement techniques used for the investigation of electric field tunable spintronic devices.
2.1 Sample Preparation Techniques 2.1.1 Pulsed Laser Deposition Method With the development of laser technology and the relevant applications, a new kind of thin film preparation technology which employs laser as the heat source, i.e., pulsed laser deposition, was first attempted by Smith et al. Later it was developed by Vankatesan et al. in Bell Laboratories of the USA [1] and was widely used in the preparation of high-temperature superconducting, ferroelectric materials, and magnetic oxides. The principle and basic configuration of the pulsed laser deposition [2, 3] is shown in Fig. 2.1. When a high-energy pulsed laser beam emitted by a laser generator passes through a series of optical system and is finally focused on the target inside a chamber, the temperature of the target surface is instantaneously heated up S. Zhang, Electric-Field Control of Magnetization and Electronic Transport in Ferromagnetic/Ferroelectric Heterostructures, Springer Theses, DOI: 10.1007/978-3-642-54839-0_2, Springer-Verlag Berlin Heidelberg 2014
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2 Experimental Methods
Fig. 2.1 Schematic diagram of the PLD technology (Reprinted from Ref. [3], Copyright 2010, with permission from Elsevier)
to 2000–3000 K by the high-energy density released from the focused laser beam. Due to the high temperature, the materials inside the target are instantaneously vaporized and ionized, forming complex plasma containing atoms, molecules, ions, and neutral particles. With the continuous absorption of laser energy and further ionization of the materials in the target, the temperature and pressure inside the plasma increase rapidly. As a result, the plasma was ejected perpendicular to the target surface due to the ultra-high-pressure gradient and forms a plume (plasma plume). In the diffusion process of the plasma plume, the interaction between the plasma and the atmosphere inside the chamber will continuously increase the ionization process and the c
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