• Title :  Optical properties of NbCl5 and ZnMg intercalated graphite             compounds
  • Author : Eilho Jung, Seokbae Lee, Seulki Roh, Xiuqing Meng, Sefaattin Tongay, Jihoon Kang, Tuson Park and Jungseek Hwang
  • Journal :2014 J. Phys. D: Appl. Phys. 47 485304 
  • Link : http://dx.doi.org/10.1088/0022-3727/47/48/485304
  • Abstract : 
    We studied NbCl5 and ZnMg alloy intercalated graphite compounds using an optical spectroscopy technique. These intercalated metallic graphite samples were quite challenging to obtain optical reflectance spectra since they were not flat and quite thin. By using both a new method and an in situ gold evaporation technique we were able to obtain reliable reflectance spectra of our samples in the far and mid infrared range (80–7000 cm−1). We extracted the optical constants including the optical conductivity and the dielectric function from the measured reflectance spectra using a Kramers–Kronig analysis. We also extracted the dc conductivity and the plasma...
  • Title :  Synthesis and pressure effects on the La doped CaFe2As2
  • Author : Soohyeon Shin, T. Shang, H. Q. Yuan, Tuson. Park
  • Journal :Progress in Superconductivity and Cryogenics Vol.16, No.1,                (2014), pp.1~5  
  • Link : http://dx.doi.org/10.9714/psac.2014.16.1.001
  • Abstract : 
    We have synthesized La doped CaFe2As2single crystals with Sn flux in an evacuated quartz ampule. Doping and pressure effects on the magnetic and superconducting properties of the under-doped Ca1-xLaxFe2As2 (x=0.08, 0.1) were studied by measuring electrical resistivity under quasi-hydrostatic pressure up to 21 kbar. Magnetic transition temperatures for all studied concentrations were sharply suppressed with slight amplitude of pressure, less than 3kbar, while superconducting transition temperatures were robust against pressure. In this communication, we report temperature-pressure phase diagram for the La-doped CaFe2As2 single crystals.
  • Title :  Nanoscale topographical replication of graphene architecture by artificial DNA nanostructures
  • Author : Y. Moon, J. Shin, S. Seo, J. Park, S. R. Dugasani, S. H. Woo,                T. Park , S. H. Park, and J. R. Ahn
  • Journal :APPLIED PHYSICS LETTERS104, 231904 (2014) 
  • Link : http://dx.doi.org/10.1063/1.4882241
  • Abstract : 
    Despite many studies on how geometry can be used to control the electronic properties of graphene, certain limitations to fabrication of designed graphene nanostructures exist. Here, we demonstrate controlled topographical replication of graphene by artificial deoxyribonucleic acid (DNA) nanostructures. Owing to the high degree of geometrical freedom of DNA nanostructures, we controlled the nanoscale topography of graphene. The topography of graphene replicated from DNA nanostructures showed enhanced thermal stability and revealed an interesting negative temperature coefficient of sheet resistivity when underlying DNA nanostructures were denatured at high temperatures.