Structural, surface morphology and magneto-transport properties of self flux grown Eu doped Bi₂Se₃ single crystal

Abstract

Here, we report the effect of europium (Eu) doping in Bi 2 Se 3 topological insulator (TI) by using different characterization techniques viz. X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDXA) and magneto-transport measurements. Good quality Eu doped Bi 2 Se 3 (Eu 0.1 Bi 1.9 Se 3 ) single crystal is grown by the self flux method through the solid state reaction route. Single crystal XRD pattern displayed the high crystalline quality of the Eu 0.1 Bi 1.9 Se 3 sample along (00l) alignment whereas; the powder XRD confirmed the rhombohedral crystal structure without any impurity phases. SEM images exhibited a layered slab like structure stacked one over the other whereas; EDXA measurements confirmed the chemical composition of Eu 0.1 Bi 1.9 Se 3 sample. Further, the EDXA mapping showed the homogeneous distribution of Bi, Se and Eu elements. Temperature dependent electrical resistivity curves revealed a metallic behaviour both in the presence and absence of applied magnetic field. Magneto-transport measurements showed a decrease in the magneto-resistance (MR) value of the Eu 0.1 Bi 1.9 Se 3 sample (~32% at 5K) in comparison to the pure Bi 2 Se 3 sample (~80% at 5K). For, Eu 0.1 Bi 1.9 Se 3 sample, a complex crossover between WL and WAL phenomenon was observed at lower applied magnetic fields, whereas the same was absent in case of the pristine one. Further, HLN (Hikami Larkin Nagaoka) fitted magneto-conductivity (MC) analysis revealed a competing weak anti localization (WAL) and weak localization (WL) behaviour. Summarily, in the present work we study the structural, surface morphology and magneto-transport properties of as grown Eu 0.1 Bi 1.9 Se 3 single crystals.

Surface states induced weak anti-localization effect in Bi0.85Sb0.15 topological single crystal

“…The binary mixture then pelletized and sealed into an evacuated quartz tube. The single crystals were grown by following the heat treatment as reported earlier [17]. The quartz tube was heated to 650°C, and kept hold for 8 hours in order to get homogenized mixture.…”

2D Weyl‐Semimetal States Achieved by a Thickness‐Dependent Crossover and Topological Phase Transition in Bi0.96Sb0.04 Thin Films

“…[ 33,45–46 ] Four principal Raman peaks are evident in Bi 1‐x Sb x system with rhombohedral R$$\bar{3}$$m symmetry. [ 47,48 ] Two of them, observed at ≈72–75 and ≈97–100 cm −1 , are attributed to E g (Bi) and A 1g (Bi) Bi–Bi vibration modes, respectively, and the other two, observed at ≈118–120 and ≈138–141 cm −1 , originate from E g (Sb) and A 1g (Sb) Sb–Sb vibration modes, respectively. [ 47,49,50 ] Here, four Raman peaks were visible for the film of 300 nm thickness but they were not well resolved (Figure S11a, Supporting Information).…”

“…[ 47,48 ] Two of them, observed at ≈72–75 and ≈97–100 cm −1 , are attributed to E g (Bi) and A 1g (Bi) Bi–Bi vibration modes, respectively, and the other two, observed at ≈118–120 and ≈138–141 cm −1 , originate from E g (Sb) and A 1g (Sb) Sb–Sb vibration modes, respectively. [ 47,49,50 ] Here, four Raman peaks were visible for the film of 300 nm thickness but they were not well resolved (Figure S11a, Supporting Information). For other thicknesses, the visibility of the Sb peaks, E g (Sb) and A 1g (Sb), were clear enough to evaluate their shifts; There was little change in the locations of these peaks for the film thicknesses > 10 nm but clear blue shifts were observed for thicknesses < 10 nm (Figure S11b, Supporting Information).…”