STM study on Dirac Nodal Line Semimetal GdAsSe

Pei-Fang Chung^1*, Balaji Venkatesan¹, Syu-you Guan¹, Horng-Tay Jeng^2,3, Cheng-Maw Cheng⁴, Raman Sankar¹, Tien-Ming Chuang¹

¹Institute of Physics, Academia Sinica, Taiwan
²Department of Physics, National Tsing Hua University, Taiwan
³Physics Division, National Center for Theoretical Sciences, Taiwan
⁴National Synchrotron Radiation Research Center, Taiwan

* Presenter:Pei-Fang Chung, email:pfchung@gate.sinica.edu.tw

Non-symmorphic semimetal ZrSiS family has attracted increasing attention due to its topological nodal-line band structure. Rare-earth material GdAsSe which exhibits a monoclinic crystal structure and an antiferromagnetic transition temperature around T = 15 K, represents a promising candidate for understanding the structural effect on the Dirac nodal line as well as tuning topological band structure via magnetic order using magnetic field and temperature. In this work, we studied GdAsSe single crystals at T~4.2 K by using a homemade scanning tunneling microscope (STM). The topography and corresponding Fourier-transformed images show the cleaved surface is Se-termination. We obtained quasiparticle scattering interference (QPI) images in real space by taking differential conductance maps, dI/dV (r, E=-0.5eV to 1eV). The corresponding Fourier-transformed images, dI/dV (q,E) maps, reveal several dispersing q-vectors. We conclude these q-vectors were primarily dominated by impurity states and the scattering between the surface bands of GdAsSe. We will compare our SI-STM results with the band structure measured by ARPES measurements and DFT calculations and discuss the implication to the nodal line band structure in GdAsSe.

Keywords: Topological materials, Non-symmorphic semimetal, Dirac nodal line, Scanning tunneling microscope