Abstract:

"Elementary particles are the architect of the nature." It is this simple philosophy that shaped natural sciences. Interestingly enough, in some electronic materials such as doped Mott insulators, at short scales, electrons can be effectively fractionalized into more "elementary" particles-holons and spinons-carrying the charge and spin degrees of freedom. What kind of quantum statistics do they obey? How do they form quantum matters at large scales? It has been recognized very recently that these questions may provide a key to many hard-core issues in strongly correlated systems such as high Tc superconductivity. In this talk, I will present a case study of these questions in the context of lightly doped antiferromagnets (spin 1/2). I will first explain how canonical theories of phase transitions are challenged by "electron fractionalization". Then, I will discuss how a peculiar statistics, the so-called mutual statistics, emerges due to electron fractionalization. Finally, I will explain how the zero-temperature phase diagram deeply roots in such a peculiar statistics and is characterized by a pair of Wilson loops. I will show the existence of a novel phase-the Bose insulator phase-that separates the antiferromagnetic and superconducting phases, and the quantum transitions between them are far beyond the Landau-Ginzburg-Wilson paradigm.
 
 
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