Emergent phenomena in quantum phase transition

Abstract

Emergent phenomena near the quantum critical point at sufficiently low temperature attracts accumulating attentions with respect to both theories and applications. On the contrary to materials with itinerant electrons, ferroelectric materials are relatively less studied but promising in studying novel quantum orders. In this report, we focus on one clean model system, strontium titanite oxide, to explore the quantum criticality. The stabilization of a quantum paraelectric phase has been verified by the previous experimental observation of the dielectric permittivity saturating at a rather high value to the order of 104 under 4 Kelvin. To understand the underlying mechanism, we apply the quantum generalization of Ginzburg-Landau theory as well as lattice dynamics, i.e., the stiffness of soft phonon mode to rationalize the deviation from the classical paraelectric to ferroelectric phase transitions. Besides, under the effective upper critical dimension, a logarithmic correction of the relationship between relative permittivity and temperature could explain the upturn found in diagram.