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Register a new userCrystal growth and superconductivity of FeSe_x
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Single crystals FeSe_x have been grown in evacuated sealed quartz tube using a NaCl/KCl flux. The products include two crystal structures of tetragon and hexagon. The electronic transport and magnetic properties measurements of FeSe_x single crystal exhibits a superconducting transition at about 10K.
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Superconductivity was discovered in a Ni0:05TaS2 single crystal. A Ni0:05TaS2 single crystal was successfully grown via the NaCl/KCl flux method. The obtained lattice constant c of Ni0:05TaS2 is 1.1999 nm, which is significantly smaller than that of 2H-TaS2 (1.208 nm). Electrical resistivity and magnetization measurements reveal that the superconductivity transition temperature of Ni0:05TaS2 is enhanced from 0.8 K (2H-TaS2) to 3.9 K. The charge-density-wave transition of the matrix compound 2H-TaS2 is suppressed in Ni0:05TaS2. The success of Ni0:05TaS2 single crystal growth via a NaCl/KCl flux demonstrates that NaCl/KCl flux method will be a feasible method for single crystal growth of the layered transition metal dichalcogenides.
We investigated the occurrence and nature of superconductivity in single crystals of YFe$_2$Ge$_2$ grown out of Sn flux by employing x-ray diffraction, electrical resistivity, and specific heat measurements. We found that the residual resistivity ratio (RRR) of single crystals can be greatly improved, reaching as high as $sim$60, by decanting the crystals from the molten Sn at $sim$350$^circ$C and/or by annealing at temperatures between 550$^circ$C and 600$^circ$C. We found that samples with RRR $gtrsim$ 34 showed resistive signatures of superconductivity with the onset of the superconducting transition $T_capprox1.4$ K. RRR values vary between 35 and 65 with, on average, no systematic change in $T_c$ value, indicating that systematic changes in RRR do not lead to comparable changes in $T_c$. Specific heat measurements on samples that showed clear resistive signatures of a superconducting transition did not show any signature of a superconducting phase transition, which suggests that the superconductivity observed in this compound is either some sort of filamentary, strain stabilized superconductivity associated with small amounts of stressed YFe$_2$Ge$_2$ (perhaps at twin boundaries or dislocations) or is a second crystallographic phase present at levels below detection capability of conventional powder x-ray techniques.
Single crystal of Cu0.03TaS2 with low copper intercalated content was successfully grown via chemical iodine-vapor transport. The structural characterization results show that the copper intercalated 2H-Cu0.03TaS2 single crystal has the same structure of the CdI2-type structure as the parent 2H-TaS2 crystal. Electrical resistivity and magnetization measurements reveal that 2H-Cu0.03TaS2 becomes a superconductor below 4.2 K. Besides, electrical resistivity and Hall effects results show that a charge density wave transition occurs at TCDW = 50 K.
In this letter, we report growth and characterization of bulk Bi2Se3 single crystals. The studied Bi2Se3 crystals are grown by self flux method through solid state reaction from high temperature (950C) melt of constituent elements and slow cooling (2C/hour). The resultant crystals are shiny and grown in [00l] direction, as evidenced from surface XRD. Detailed Reitveld analysis of PXRD (powder x-ray diffraction) of the crystals showed that these are crystallized in rhombohedral crystal structure with space group of R3m (D5) and the lattice parameters are a = 4.14(2)A, b = 4.14 (2) A and c = 28.7010(7) A. Temperature versus resistivity (R-T) plots revealed metallic conduction down to 2K, with typical room temperature resistivity (R300K) of around 0.53 mohm-cm and residual resistivity of 0.12 mohm-cm. Resistivity under magnetic field ] measurements exhibited large +Ve magneto resistance right from 2K to 200K. Isothermal magneto resistance [RH] measurements at 2K, 100K and 200K exhibited magneto resistance (MR) of up to 240, 130 and 60 percent respectively at 14 Tesla. Further the MR plots are non saturating and linear with field at all temperature. At 2K the MR plots showed clear quantum oscillations at above say 10 Tesla applied field. Also the Kohler plots i.e., were seen consolidating on one plot. Interestingly, the studied Bi2Se3 single crystal exhibited the Shubnikov-de Haas oscillations (SdH) at 2K under different applied magnetic fields ranging from 4Tesla to 14 Tesla
To investigate the origin of the enhanced Tc ({approx} 110 K) of the trilayer cuprate superconductor Bi2Sr2Ca2Cu3O10+{delta} (Bi-2223), its underdoped single crystals are a critical requirement. Here, we demonstrate the first successful in-plane resistivity measurements of heavily underdoped Bi-2223 (zero-resistivity temperatures {approx} 20~35 K). Detailed crystal growth methods, the annealing process, as well as X-ray diffraction (XRD) and magnetic susceptibility measurement results are also reported.
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