Electrons in Solids and Quantum Phase Transition

Abstract

Quantum phases in solids―superconducting phase, for example―suddenly appear and fascinate us. These changes are driven by phase transitions, which are induced not only by thermal fluctuations but also by quantum fluctuations. And under conditions with strong quantum effects, they are difficult to predict and calculate. Understanding the known patterns of quantum phase transitions induced when solids are controlled by external parameters will lead to the discovery of novel quantum phenomena. After a simple review of phase transition phenomena, this article gives examples of complex and fascinating quantum phase transitions induced by electrons in solids.