Structural Analysis and Superconducting Properties of F-Substituted NdOBiS₂ Single Crystals

Abstract

F-substituted NdOBiS 2 superconducting single crystals were grown using CsCl/KCl flux. This is the first example of the single-crystal growth of a BiS 2 -based superconductor. The obtained single crystals had a plate-like shape with a size of 1-2 mm and a well-developed ab-plane. The crystal structure of the grown crystals was determined by single-crystal X-ray diffraction analysis to be the tetragonal space group P4/nmm (#129) with a = 3.996(3) Å and c = 13.464(6) Å. The chemical formula of the grown crystals was approximately Nd 0.98±0.06 O 0.7±0.

Synthesis and Properties of SmO0.5F0.5BiS2 and Enhancement in Tc in La1–ySmyO0.5F0.5BiS2

“…[7][8][9][10] For example both these systems crystallize in the same space group (P4/nmm), they have layered structure with a charge reservoir layer (LnO) and a superconducting layer (BiS 2 , Fe-As), their parent phases are semiconducting or poorly conducting and, most importantly, they become superconducting upon electron-doping (doping F -for O 2-or a tetravalent ion for Ln). [9][10][11][12][13][14][15][16][17] Superconductivity by fluorine -doping in LaO 1-x F x BiS 2 was first reported by Mizuguchi et al (T c ~ 2.5 K) 9 ( T c ~10 K could be achieved by high pressure synthesis). 9 Superconductivity in LnO 1-x F x BiS 2 with Ln = Ce, Pr, Nd and Yb also followed soon.…”

“…9 Superconductivity in LnO 1-x F x BiS 2 with Ln = Ce, Pr, Nd and Yb also followed soon. [10][11][12][13][14][15][16] T c is enhanced by chemical pressure [18][19][20] or external applied pressure [22][23][24][25][26][27] as observed for LnOFeAs 28 for example in LnO 1-x F x BiS 2 , a slight enhancement in T c has been reported by substituting Se at the S sites or by inter-mixing rare earth ions. [18][19][20][21] Hole doping via alkali earthmetal-substitution at Ln-site did not yield superconductivity.…”

“Checkerboard Stripe” Electronic State on Cleaved Surface of NdO0.7F0.3BiS2 Probed by Scanning Tunneling Microscopy

“…The recent discovery of BiS 2 -based superconductors has triggered many research activities, because of (i) the structural similarity to cuprates and pnictides and (ii) their relatively high T c [19][20][21][22][23][24][25][26][27] . Recent theoretical calculations have suggested that a quasi-one-dimensional character of the band dispersion provides a good Fermi surface nesting [28][29][30][31][32] .…”

“…The single crystals used in this study were grown by a high-temperature flux method 25 . The superconducting transition temperature of 5.1 K was determined by magnetization and resistivity measurements 25 .…”

“…The superconducting transition temperature of 5.1 K was determined by magnetization and resistivity measurements 25 . The STM and STS measurements were performed in a helium-gas environment at 4.2 and 22 K using a laboratory-built STM.…”