Organic Based Magnetic Thin Films by Low Temperature CVD

Abstract

We describe how the composition of an organic - based magnet can be controlled by varying the Chemical Vapor Deposition (CVD) conditions. A study was conducted for the Co2(CO)8/ TCNE system to form cobalt tetracyanoethylene [Co(TCNE)x, x∼2, a paramagnetic material], and for the V(CO)6/ TCNEx system to form vanadium tetracyanoethylene [V(TCNE)x, x∼2, a ferrimagnetic material]. Thin V(TCNE)x, x∼2 films (∼0.05-0.5 μm) with room temperature conductivity of 10-4<σRT<10-3S/cm and magnetic ordering temperature Tc of up to ∼400K were deposited. The V(TCNE)x, x∼2 thin films have the potential for incorporation in a spin-valve device as one of the magnetic contacts, and are promising candidates to form optically controlled magnetic-based structures.

Chemical Vapor Deposition of an Organic Magnet, Vanadium Tetracyanoethylene

“…Because the chemical vapor deposition set-up is not commercially available these parameters will need to be optimized for each system. A previous study by Shima et al revealed that the temperature has the largest impact on the sublimation rate of the TCNE precursor 26 . The temperature can be modified both by the value set on the temperature controller and also by making adjustments to the wire spacing on the heating coil and as such will need to be calibrated for each system.…”

Thin films of coordination polymer magnets

“…38 The CVD grown film was magnetic above room temperature, as is known for the solvent synthesized powders, and in fact, revealed a slightly higher ordering temperature. 38,66 These papers are important because they showed that CVD can successfully be used to prepare thin films of organic magnets onto a variety of substrates. Also, the CVD films, because they possess fewer defects and are denser than the normally studied powders, exhibit different properties, including enhanced air-stability and higher magnetic ordering temperature.…”

“…Its air sensitivity has led to solvent free preparations that are more stable, and the volatility of the molecular precursors naturally led to preparations using vapor deposition. 38,[63][64][65][66] Although the vanadium analog exhibits the most impressive properties, several other M [TCNE] x magnets are also known, and many have also been prepared using vapor deposition.…”