Pseudogap and Weak Multifractality in 2D Disordered Mott Charge-Density-Wave Insulator

• DOI: 10.1021/acs.nanolett.0c01607
• Publication Date: 2020-07-31T21:07:26Z
• Authors: Jianhua Gao; Jae Whan Park; Kiseok Kim; Sun Kyu Song; Hae Ryong Park; Jhinhwan Lee; Jewook Park; Fangchu Chen; Xuan Luo; Yuping Sun; Han Woong Yeom
• Keywords: 0303 health sciences; SUPERCONDUCTIVITY; PHASE; charge density wave; disorder; transition metal dichalcogenide; Mott insulator; STATE; 03 medical and health sciences; multifractality; pseudogap; 1T-TAS2; TRANSITION

We investigate electronic states of Se-substituted 1T-TaS2 by scanning tunneling microscopy/spectroscopy (STM/STS), where superconductivity emerges from the unique Mott-charge-density-wave (Mott-CDW) state. Spatially resolved STS measurements reveal that a pseudogap replaces the Mott gap with the CDW gaps intact. The pseudogap has little correlation with the unit-cell-to-unit-cell variation in the local Se concentration but appears globally. The correlation length of the local density of states (LDOS) is substantially enhanced at the Fermi energy and decays rapidly at high energies. Furthermore, the statistical analysis of LDOS indicates the weak multifractal behavior of the wave functions. These findings suggest a correlated metallic state induced by disorder and provide a new insight into the emerging superconductivity in two-dimensional materials.