Visualizing the evolution from Mott insulator to Anderson insulator in Ti-doped 1T-TaS2
Wenhao Zhang, Jingjing Gao, Li Cheng, Kunliang Bu, Zongxiu Wu, Ying Fei, Yuan Zheng, Li Wang, Fangsen Li, Xuan Luo, Zheng Liu, Yuping Sun, Yi Yin
Abstract
Abstract The electronic evolution of doped Mott insulators has been extensively studied for decades in search of exotic physical phases. The proposed Mott insulator 1 T -TaS 2 provides an intriguing platform to study the electronic evolution via doping. Here we apply scanning tunneling microscopy (STM) to study the evolution in Ti-doped 1 T -TaS 2 at different doping levels. The doping Ti atom locally perturbs the electronic and spin state inside the doped star of David and induces a clover-shaped orbital texture at low-doping levels ( x < 0.01). The insulator to metal transition occurs around a critical point x = 0.01, in which small metallic and large insulating domains coexist. The clover-shaped orbital texture emerges at a broader energy range, revealing a competition with the electron correlation. It transforms to a disorder-induced Anderson insulating behavior as doping increases. We directly visualize the trapped electrons in d I / d V conductance maps. The comprehensive study of the series of Ti-doped 1 T -TaS 2 deepens our understanding of the electronic state evolution in a doped strong-correlated system.