Crystal Growth by the Floating Zone Method of Ce-Substituted Crystals of the Topological Kondo Insulator SmB6

Abstract

SmB6 is a mixed valence topological Kondo insulator. To investigate the effect of substituting Sm with magnetic Ce ions on the physical properties of samarium hexaboride, Ce-substituted SmB6 crystals were grown by the floating zone method for the first time as large, good quality single crystal boules. The crystal growth conditions are reported. Structural, magnetic and transport properties of single crystals of Sm1−xCexB6 (x=0.05, 0.10 and 0.20) were investigated using X-ray diffraction techniques, electrical resistivity and magnetisation measurements. Phase composition analysis of the powder X-ray diffraction data collected on the as-grown boules revealed that the main phase was that of the parent compound, SmB6. Substitution of Sm ions with magnetic Ce ions does not lead to long-range magnetic ordering in the Sm1−xCexB6 crystals. The substitution with 5% Ce and above suppresses the cross-over from bulk conductivity at high temperatures to surface-only conductivity at low temperatures.

An STM perspective on hexaborides: Surface states of the Kondo insulator SmB$_6$

“…With the proposal of non-trivial topology in EuB 6 [146], the series Sm 1−x Eu x B 6 is certainly of topical interest [147][148][149]. Other magnetic substitutions include Gd [72,102,128,147,150], Ce [151] and Fe [128,152,153].…”

An STM Perspective on Hexaborides: Surface States of the Kondo Insulator SmB6

“…With the proposal of nontrivial topology in EuB 6 , [ 146 ] the series SmEu x B 6 is certainly of topical interest. [ 147–149 ] Other magnetic substitutions include Gd, [ 72,103,128,147,150 ] Ce, [ 151 ] and Fe. [ 128,152,153 ]…”

Advances on topological materials

“…The data suggest that it is bulk conductivity, modified by crystalline electric field and Kondo effects alongside phonon scattering, that determines the form of the ρ (T) curves for these Sm 1−x Ce x B 6 samples over the entire temperature range studied. A more quantitative description of the transport properties of the Sm 1−x Ce x B 6 crystals, including extensive measurements in a magnetic field, will be presented elsewhere [76].…”