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A New SCIENCE Paper about Inherent Mott Metal-to-Insulator Transition
Broadly speaking, a material can be classified as a metal if it contains itinerant electric charges ready for carrying electric current. The opposite is true in the case of insulators. In these, electric charges are localized and cannot move, so no electric conductivity exists. In a new class of so called correlated electron materials, such as high-temperature superconductors, electrons strongly interact and give rise to extraordinary phenomena including superconductivity. One such phenomenon is the Mott metal-insulator transition, originally discovered by Sir Nevill Mott, who won the 1977 Nobel Prize in Physics for his study of phase transitions from a metal to an insulator in certain materials, and for showing that these transitions are inherently driven by electron-electron interactions. Experimentally, Mott transitions can be produced but nearly always are accompanied by a structure transition, until now. In the October 26 issue of SCIENCE (volume 318, page 615), Prof. Jiandi Zhang of the Department of Physics, in collaboration with Prof. Plummer’s group at the University of Tennessee-Knoxville (UTK), R. Jin and D. Mandrus at Oak Ridge National Laboratory (ORNL), as well as his colleagues at the Institute of Physics in Beijing, China, demonstrates that a purely electronic Mott metal-to-insulator transition occurs at a crystalline surface of a transition-metal oxide. The broken translational symmetry at the surface creates this phase transition without participation of a crystal structural transformation. This finding offers a unique opportunity to gain insight into the nature of an inherent Mott transition, which is a key topic of study in condensed matter physics
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Group Overview
The research of Zhang’s group is exploring novel properties of complex materials like transition-metal oxides by the effects of reduced dimensionality and broken symmetry, with emphasis on the intimate coupling among charge, lattice, orbital, and spin degrees of freedom. Ongoing research projects include the phenomena at a surface and an interface of transition metal oxides and ordered polymer materials by using scanning tunneling probes, electron scattering, and photoemission; and correlated electron materials by using neutron scattering. Our work is supported by the National Science Fundation and Department of Energy.
