Magnetoresistance Property and Electronic Structure in Amorphous a-C:Co Films

• Main Authors: Chuang, Pei-Yu, 莊霈于
• Other Authors: Lee, Chih-Hao
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/52142637645593710595

碩士 === 國立清華大學 === 工程與系統科學系 === 100 === Recent studies of large magneto-resistance (MR) effect in several distinct mechanisms and systems have gained much attention because the MR ratio is comparable to, or even larger than, that of MR caused by a typical spin-dependent scattering mechanism discovered in magnetic multilayers. For examples, large positive MR induced by the space-charge effect has been achieved in metal-semiconductor hybrid devices. Besides, colossal MR related to switching the conducting channels between different layers has also been observed. In this report, we study anomalous giant MR effect in amorphous a-C:Co films on the quartz substrate. These films, investigated in current-in-plane geometry, has a bias voltage dependent positive magneto-resistance (PMR), and at room temperature, the MR value reaches 10% under a relative low magnetic field H=0.3 (T) and bias voltage of 4V. By using Raman spectrum、X-ray Reflectivity(XRR)、X-ray Absorption Spectrum(XAS)、Ultra-Violet Photoemission Spectrum(UPS) and Superconducting Quantum Interference Device(SQUID), we measure a-C:Co films the mass density、electron structure and magnetic properties to investigation of coupling the electro-transport. The result of Co and Carbon electron orbital to hybrid, and applied external magnetic field the Co d orbital will be split by Zeeman Effect. And then maybe distorted a-C:Co Fermi level to effect electro-transport.