Spin-dependent Transport Properties of CrO2 Micro Rod

• Published in: Nano-micro letters 2014-10, Vol.6 (4), p.365-371
• Main Authors: Wang, Zhen, Xi, Li, Yang, Yikai, Li, Yue, Han, Xuemeng, Zuo, Yalu, Wang, Jianbo
• Format: Article
• Language: English
• Subjects: Bias voltage dependence; CrO2 rod; Direct current; Engineering; Low-field magnetoresistance; Magnetic properties; Magnetoresistance; Magnetoresistivity; Nanoscale Science and Technology; Nanotechnology; Nanotechnology and Microengineering; Photoelectric emission; Precursors; Transport properties; Tunneling barrier
• ISSN: 2150-5551; 2311-6706; 2150-5551
• DOI: 10.1007/s40820-014-0010-8

The Cr O2 micro rod powder was synthesized by decomposing the Cr O3 flakes at a specific temperature to yield precursor and annealing such a precursor in a sealed glass tube. The magneto-transport properties have been measured by a direct current four-probe method using a Cu/Cr O2rods/colloidal silver liquid electrode sandwich device. The largest magnetoresistance(MR) around *72 % was observed at 77 K with applied current of 0.05 l A. The non-linear I–V curve indicates a tunneling type transport properties and the tunneling barrier height is around 2.2 ± 0.04 e V at 77 K, which is obtained with fitting the non-linear I–V curves using Simmons’ equation. A mixing of Cr oxides on the surface of Cr O2 rod observed by X-ray photoemission spectroscopy provides a tunneling barrier rather than a single phase of Cr2O3 insulating barrier. The MR shows strong bias voltage dependence and is ascribed to the two-step tunneling process.