Magnetism of Cr-Doped Diamond-Like Carbon

Authors

J. A. Colón Santana, University of Nebraska-Lincoln
Ralph Skomski, University of Nebraska-LincolnFollow
V. R. Singh, Louisiana State University, Baton RougeFollow
V. Palshin, Louisiana State University, Baton Rouge
A. Petukhov, South Dakota School of Mines
Yaroslav B. Losovyj, Louisiana State University at Baton RougeFollow
Andrei Sokolov, University of Nebraska-LincolnFollow
Peter A. Dowben, University of Nebraska-LincolnFollow
Ihor Ketsman, University of Nebraska-LincolnFollow

Date of this Version

2009

Comments

Published in JOURNAL OF APPLIED PHYSICS 105, 07A930 (2009). Copyright © 2009 American Institute of Physics. Used by permission.

Abstract

Chromium-doped hydrogenated diamond-like carbon (Cr-DLC) and chromium carbide hydrogenated DLC alloys were synthesized by plasma-assisted vapor deposition and investigated by x-ray absorption near edge structure spectroscopy, extended x-ray absorption fine structure, and superconducting quantum interference device (SQUID) magnetometry. Structural and magnetic properties of the doped and alloy materials were investigated as a function of the Cr concentration (0.1–20 at. %). Toward the upper end of the concentration range, Cr precipitates in the form of chromium carbide (Cr₃C₂) nanoclusters. For low Cr concentrations, the systems are ferromagnetic at very low temperatures, whereas the chromium carbide clusters appear to be antiferromagnetic with uncompensated spins at the surface. Cr-DLC films and alloys with various Cr concentrations are used to make heterojunctions on silicon, and the produced diodes are investigated by I-V measurements. The heterojunctions exhibit negative magnetoresistance that saturates at less than 500 Oe and may be suitable for spin-electronics applications.