215 research outputs found
Atomic-scale flattening of SiC surfaces by electroless chemical etching in HF solution with Pt catalyst
The authors present a method for flattening SiC surfaces with Pt as a catalyst in HF solution. The mechanism for flattening SiC surfaces is discussed. The flattened 4H-SiC (0001) surface is composed of alternating wide and narrow terraces with single-bilayer-height steps, which are induced by the rate difference of the catalytic reactions between adjacent terraces. Scanning tunneling microscopy images reveal a 1×1 phase on the terraces. The 1×1 phase is composed of coexisting of F- and OH-terminated Si atoms, which originate from the polarization of the underlying Si-C bonds. © 2007 American Institute of Physics.Kenta Arima, Hideyuki Hara, et al. "Atomic-scale flattening of SiC surfaces by electroless chemical etching in HF solution with Pt catalyst", Appl. Phys. Lett. 90(20), 202106 (2007) https://doi.org/10.1063/1.2739084
Enhancement of superconducting properties in FeSe wires using a quenching technique
Enhancements of superconducting properties were observed in FeSe wires using
a quenching technique. Zero resistivity was achieved at about 10 K in quenched
wires, which is about 2 K higher than that of polycrystalline FeSe bulk.
Furthermore, transport Jc of quenched wires showed three times higher than that
of furnace-cooled wires. In contrast, the quenched polycrystalline FeSe bulks
did not show the enhancement of Tc. The quenching technique is a greatly
promising for fabricating FeSe wires with high Tc and high Jc, and quenched
FeSe wires have high potential for superconducting wire applications
Evolution of superconductivity in isovalent Te-substituted KxFe2-ySe2 crystals
We report the evolution of superconductivity and the phase diagram of the
KxFe2-ySe2-zTez (z=0-0.6) crystals grown by a simple one-step synthesis. No
structural transition is observed in any crystals, while lattice parameters
exhibit a systematic expansion with Te content. The Tc exhibits a gradual
decrease with increasing Te content from Tconset = 32.9 K at z = 0 to Tconset =
27.9 K at z = 0.5, followed by a sudden suppression of superconductivity at z =
0.6. Upon approaching a Te concentration of 0.6, the shielding volume fraction
decreases and eventually drops to zero. Simultaneously, hump positions in r-T
curve shift to lower temperatures. These results suggest that isovalent
substitution of Te for Se in KxFe2-ySe2 crystals suppresses the
superconductivity in this system.Comment: 10 pages, 1 table, 8 figure
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