Allan MacDonald

Allan MacDonald (born December 1, 1951, Antigonish, Nova Scotia, Canada) is a Canadian-American physicist known for his work on condensed matter, particularly with graphene.

MacDonald received a bachelor’s degree (1973) from St. Francis Xavier University in Antigonish, Nova Scotia, and then a master’s (1974) and a doctorate (1978) in physics from the University of Toronto. From 1980 to 1987 he worked as a researcher at the National Research Council of Canada at Ottawa. He was a professor at Indiana University in Bloomington from 1987 to 2000. In 2000 he joined the University of Texas at Austin as a professor.

In 2011 MacDonald and Israeli physicist Rafi Bistritzer published results of their models of bilayer graphene. Graphene is crystalline carbon in the form of a two-dimensional layer, and bilayer graphene is two such layers, one on top of the other. MacDonald and Bistritzer modeled bilayer graphene and predicted that, if one layer is rotated with respect to the other by about 1.05 degrees, the velocity of electrons through graphene would go to zero, and the graphene would become an insulator, when it is normally an excellent conductor. In 2018 Spanish physicist Pablo Jarillo-Herrero and collaborators performed experiments that verified the predictions of MacDonald and Bistritzer. They found that, by applying a slight voltage, the bilayer graphene would change from an insulator to a superconductor (that is, a material with zero electrical resistance). Such a change also occurs in high-temperature superconductors called cuprates. Because bilayer graphene is easier to study than cuprates, physicists surmise that experiments with bilayer graphene will lead to better understanding of superconductivity.

MacDonald has received the Herzberg Medal (1987), the Buckley Prize (2007, with James P. Eisenstein and Steven M. Girvin), and the Wolf Prize (2020, with Jarillo-Herrero and Bistritzer). In addition, he is a fellow of the National Academy of Sciences.