Summary: Physica B 368 (2005) 131138
Electronic properties of field aligned CrO2 powders
D. Tripathy, A.O. AdeyeyeĆ
Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, 4 Engineering Drive 3,
National University of Singapore 117576, Singapore
Received 23 December 2004; received in revised form 5 July 2005; accepted 6 July 2005
We have investigated in detail the electronic transport properties of half metallic CrO2 powder-based devices,
fabricated using optical lithography and field alignment technique. A transition in the conduction mechanism from
spin-dependent intergranular tunneling to inelastic hopping was observed at 215 K. This transition temperature shifts to
230 K in the presence of 10 kOe field cooling due to reduction of the spin-independent hopping conductance channel.
IV characteristics exhibit strong temperature dependence and are non-linear even at room temperature. Our
experimental results are in good agreement with a simple theoretical model. A novel `double switching' phenomenon
was observed in the IV curves below the transition temperature.
r 2005 Elsevier B.V. All rights reserved.
PACS: 72.15.Gd; 73.40.Gk
Keywords: Half metals; CrO2; Intergranular tunneling; Inelastic hopping
Half metals are unusual ferromagnets that have
electrons at the Fermi level in a single spin state,