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Microstructure, Magnetic and Transport Properties of Fe3O4 Based Heterostructures

Author: ZhangLeTao
Tutor: BaiHaiLi
School: Tianjin University
Course: Materials Physics and Chemistry
Keywords: Heterojunction Magneto-transport properties Magnetoresistance Interface Spin polarization.
CLC: TN304.21
Type: Master's thesis
Year: 2010
Downloads: 26
Quote: 0
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Abstract


Semi-metal - semiconductor heterojunction has potential applications in spin injection, pn junction, as well as magnetic random access memory. In recent years, Fe 3 O 4 as a high Curie temperature, the preparation of simple semi-metallic material by people's attention, and silicon is the most technologically modern industrial production mature, the most widely used semiconductor material; heterojunction by these two types of materials in the field of spintronics has important research value. On the other hand, the semi-metal - semiconductor heterostructures magnetoresistance is often in contrast with the semi-metallic intrinsic magnetoresistance symbol; heterojunction produce magnetic resistance for many reasons, including double the current model, interface, space charge effects. Caused the Fe 3 O 4 based heterojunction magnetoresistance reason a variety, so we prepared on single-crystal Si substrate of Fe 3 O 4 film and change the barrier material, and to study the impact of the barrier material on the magneto-transport properties of the heterojunction. DC reactive magnetron sputtering and RF magnetron sputtering the prepared Fe O 4 of MgO-Fe 3 O < sub> 4 / MgO, Fe 3 O 4 / MgO / Fe 3 O 4 differences the homojunction Fe O 4 Si-Fe 3 O 4 / Si, Fe 3 O 4 / MgO / Si, Fe 3 O 4 / SiO2/Si, Fe 3 O 4 / MgO/SiO2/Si heterojunction microstructure, interface composition, magnetic and transport properties of the system. Fe 3 O 4 / MgO, Fe 3 O 4 / MgO / Fe 3 O 4 the heterojunction IV curve was significant nonlinear and rectifying effect, the mechanisms of the electrical conductivity of the samples in the low bias tunneling, thermionic emission at high bias / diffusion; Magnetoresistance extremum at ~ 120 K, and the bias, this magnetoresistance with Fe 3 O 4 intrinsic magnetoresistance. Fe 3 O 4 / barrier / Si heterojunction transport properties of the barrier material. Magnetoresistance Fe 3 O 4 / Si and Fe of 3 the O 4 / a SiO2/Si heterojunction positive, while Fe 3 O 4 / MgO (3 nm) / Si heterojunction magnetoresistance is negative. The negative magnetoresistance Verwey transition related, extremum occurs at ~ 120 K at, the positive magnetoresistance Verwey transition has nothing to do. Fe 3 O 4 / barrier / Si heterojunction magnetoresistance is almost zero in the current very hour, and as the current increases gradually reaching saturation. With the magnetic field, the magnetic resistance does not change linearly as the magnetic field increases, the magnetic resistance with the increase rate of the magnetic field gradually decreases. The fe 3 the O 4 / barrier / Si heterojunction magneto-transport properties are mainly at the interface Fe 3 the O 4 spin polarization decided when Fe 3 O 4 the interface at spin polarization rate Fe of 3 O 4 film internal same negative magnetoresistance, when the Fe 3 O 4 at the interface between the spin polarization and Fe 3 < / sub> O 4 film internal positive magnetoresistance.

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CLC: > Industrial Technology > Radio electronics, telecommunications technology > Semiconductor technology > General issues > Material > Compound semiconductor > Oxide semiconductor
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