Synthesis and Characterization of quasi-two-dimensional nano-flakes of the Kitaev Magnets α-RuCl 3 and N a 2 IrO 3

Abstract

This work is divided into two part. In the first part, we have used a liquid exfolia- tion method to produce quasi two-dimensional (2D) flakes of Kitaev magnets Na 2 IrO 3 , (N a 0.85 Li 0.15 ) 2 IrO 3 and α − RuCl 3 . For this work, existing crystals of Na 2 IrO 3 and (N a 0.85 Li 0.15 ) 2 IrO 3 were used and new crystals of α−RuCl 3 were grown. By ultrasonic shaking of these crystals in an LiOH solution in ethanol, we were able to separate them into 2D sheets which are 1-3μm wide and down to 2 nm thick. SEM and AFM characterization, and thickness distribution of these flakes with varying ultrasonic shaking time on these flakes are reported. In the second part, crystals of α− RuCl 3−x Br x and α−RuCl 3 have been synthesized us- ing a self-flux growth method. A thorough chemical and structural characterization of these crystals have been carried out by SEM, EDX and Raman spectroscopy techniques. Mag- netization measurements have been performed to probe the magnetic ground state of these crystals. We have observed magnetic transition at T N = 8 K, 12 K in 4% Br substituted (sheet) and 8% Br substituted (needle) crystals respectively, indicating that the magnetic order of parent α-RuCl 3 survives on Br substitution.