Insulator-Metal Transition in CaTiO₃ Quantum Dots induced by Ultrafast Laser Pulses

摘要： Based on time dependent density functional theory (TDDFT), we have studied the interaction between ultra-fast laser pulses and two kinds of calcium titanate quantum dots (PCTO-QDs and MCTO-QDs). Under the action of localized field effect, ultrafast lasers can induce quantum dots to make the transition from insulator to metal. PCTO-QDs are ultimately metallic, while MCTO-QDs are still insulator after experiencing metal state. This is bacause the stability of the unsaturated atoms in the outermost layer of PCTO-QDs is weak and the geometric configuration of MCTO-QDs as a potential well will also reduce the damage of laser. Moreover, laser waveforms approaching the intrinsic frequency of quantum dots tend to cause the highest electron levels to cross the Fermi surface. In this paper, it is reported that the insulating quantum dots can be transformed into metal by adjusting the intensity and frequency of laser. It emphasizes the importance of local morphology by comparing the difference about two kinds of CTO-QDs. More importantly, it is a step to identify the potential properties of perovskite materials.