Significant magneto-resistive effects in boron carbide thin films

• Boron carbide can be formed by dehydrogenation of carboranes.
• Large negative magneto-resistance is seen in boroncarbide.
• Doping of boron carbide affects low voltage conductivity.
• Room temperature high magneto-resistivity suggests practical device applications.

We have found large room temperature magneto-resistance in boron carbides fabricated via electron-induced cross-linking of icosahedral closo-1,2-dicarbadodecaborane (ortho-carborane; 1,2-B10C2H12) in the presence of the aromatic compound 1,4-diaminobenzene (DAB). X-ray photoemission spectroscopy confirms that the electron beam irradiation leads to site-specific cross-linking of the ortho-carborane, with cross-linking between B sites non-adjacent to icosahedral carbon sites on the carborane moiety, and carbon sites on the diaminobenzene moiety. The I–V curves, as a function of external magnetic field, demonstrate that significant room temperature negative magneto-resistance (>50%) is possible in the resulting dielectric thin films. Inclusion of 1,4-diaminobenzene (DAB) is not essential for significant negative magneto-resistance, as crosslinking of ortho-carborane (1,2-B10C2H12 ) results in large negative magneto-resistance, over 100%, depending on bias voltage.