Seebeck and Spin Seebeck effect in Gd-doped GaN thin films for Thermoelectric Devices and Applications
- PDF / 427,388 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 91 Downloads / 215 Views
Seebeck and Spin Seebeck effect in Gd-doped GaN thin films for Thermoelectric Devices and Applications Bahadir Kucukgok1, Liqin Su2, Elisa N. Hurwitz2, Andrew Melton3, Liu Zhiqiang2, 4, Na Lu5, and Ian T. Ferguson2 1
Department of Optical Science and Engineering, University of North Carolina at Charlotte, NC, 28213, USA. 2 Department of Electrical and Computer Engineering, University of North Carolina at Charlotte, NC, 28213, USA. 3 Department of Electrical and Computer Engineering, Georgia Institute of Technology, GA, 30332, USA. 4 Semiconductor Lighting R&D Center Institute of Semiconductors Chinese Academy of Sciences, P.O. Box 912 Beijing 100083Beijing, China. 5 Department of Engineering Technology, Sustainable Material and Renewable Technology (SMART) Laboratory, University of North Carolina at Charlotte NC, 28213, USA. ABSTRACT GaN-based dilute magnetic semiconductors (DMS) have recently been investigated for use in spintronic devices. In particular, Gd-doped GaN has shown very promising room temperature ferromagnetic behavior and potential for use in spintronics applications. III-Nitride materials have recently had their thermoelectric properties investigated; however this work has not been extended to Nitride-based DMS. Understanding the spin-calorimetric characteristics of GaN-based DMS is important to the successful development of low-power spintronic devices. In this paper the Seebeck and spin-Seebeck effect in MOCVD grown Gd-doped GaN (Gd: GaN) are investigated. INTRODUCTION Manipulation of electron spins in a solid is the key to developing spin-based magnetic memories and other spintronic devices [1-3]. The thermal production of voltage for electron spins is called the spin-Seebeck effect (SSE) [4-7] and was first observed in a ferromagnetic Ni81Fe19 film via the inverse spin-Hall effect (ISHE). This was achieved by transforming a spin current into an electric current using a Pt wire attached to the ferromagnetic material [5, 6, 8, 9]. Uchida, et al, determined the spin Seebeck coefficient for Ni81Fe19 to be Ss=-2nVK-1 at 300 K [10]. The magnetic properties of III-V-based dilute magnetic semiconductors (DMS) have recently been investigated for use in spintronic devices. The spin-Seebeck effect GaMnAs, one of the most extensively studied DMS materials, has been reported [11, 12]. The spin-Seebeck effect causes a spin current and spins voltage to form in a ferromagnetic material under a temperature gradient [12-15]. The spin current is an aggregation of spin-up electron current, µ↑, in one direction and spin-down electron current, µ↓, in the opposite direction. In ferromagnetic metals, spin-up and spin-down electrons exhibit different scattering rates, densities, and Seebeck coefficients, S↑, and S↓ [10]. The results from previous studies on ferromagnetic material show that when a fixed temperature gradient (ΔT) is applied
along the sample, it leads to a spin voltage, and the difference in chemical potential, µ↑-µ↓, changes throughout the temperature gradient [10, 14-16]. In addition, the sign of the s
Data Loading...
