Gordon Yee

Research Interests

We are interested in creating room-temperature permanent magnets from organic molecules and Earth-abundant transition metals. This is a challenging problem because organic molecules are not normally open-shell species and therefore not usually useful for making magnets. Yet, the use of organic molecules as building blocks has the advantage of systematic tunability. For instance, replacing a single hydrogen atom with a fluorine atom on a molecule can produce a new molecule that is largely the same size and shape, but with different electronic properties. An example of this approach is a family of compounds we have reported that result from the reaction of vanadium hexacarbonyl, V(CO)₆, and different fluorine-substituted-phenyltricyanoethylenes (F_nPTCE, below), to produce solids of the formula V[F_nPTCE]₂. These become ferrimagnetically ordered at temperatures ranging from 160 K (no fluorine) to 315 K (fluorine in the 2,3,5 and 6 positions). Each of these solids is believed to be a network of S=3/2 V²⁺ cations bridged through the lone pairs on two or more nitrile nitrogen atoms on S=1/2 F_nPTCE radical anions to give a ferrimagnet. What we have found is that the number of fluorine atoms on the phenyl ring and their position on the ring produce systematic effects on the magnetic ordering temperature of the resulting solid, allowing us to essentially “design” new magnets.

Another aspect of our work is working with researchers around the country to measure the interesting magnetic properties of their compounds. Using our Quantum Design SQUID magnetometer, we have collaborated with groups at Georgetown (Stoll), UMSL (Holmes), Vanderbilt (Hanusa), Virginia Tech (Dorn) among many others.