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Structure and functionalities of manganite/cuprate thin film
Kumar, Manish,Phase, D.M.,Choudhary, R.J.,Lee, H.H. Elsevier 2018 Current Applied Physics Vol.18 No.suppl
<P>Bilayer thin film samples consisting of colossal magnetoresistance manganite La0.7Ca0.3MnO3 (LCMO) and superconducting cuprate YBa2Cu3O7-delta (YBCO) were stabilized by means of pulsed laser deposition techniques on single crystal SrTiO3 (001) substrate. The X-ray diffraction measurements confirm the epitaxial relationship of grown bilayer samples. The functional properties of the LCMO/YBCO bilayer were explored through magnetic and electrical transport measurements. The magnetization curve of LCMO/YBCO bilayer sample retains the characteristic ferromagnetic-paramagnetic transition of LCMO and superconducting transition of YBCO. The electrical resistivity was found to show different trend around the superconducting transition depending upon the four probe electrical contacts configuration on bilayer samples and the obtained results lead to direct visualization of proximity effect. A change in sign of magnetoresistance near the superconducting and metal to insulator transition temperature is observed which is attributed to the intrinsic property of YBCO and LCMO layers. (C) 2017 Elsevier B.V. All rights reserved.</P>
R.R. Ahire,Abhay A. Sagade,S.D. Chavhan,V. Huse,F. Singh,D.K. Avasthi,D.M. Phase,Ramphal Sharma 한국물리학회 2009 Current Applied Physics Vol.9 No.3
Modified chemical bath deposited (MCBD) bismuth sulphide (Bi2S3) thin films’ structural, optical and electrical properties are engineered separately by annealing in air for 1 h at 300 ℃ and irradiating with 100 MeV Au swift heavy ions (SHI) at 5 × 1012 ions/㎠ fluence. It is observed that the band gap of the films gets red shifted after annealing and irradiation from pristine (as deposited) films. In addition, there is an increase in the grain size of the films due to both annealing and irradiation, leading to the decrease in resistivity and increase in thermoemf of the films. These results were explained in the light of thermal spike model. Modified chemical bath deposited (MCBD) bismuth sulphide (Bi2S3) thin films’ structural, optical and electrical properties are engineered separately by annealing in air for 1 h at 300 ℃ and irradiating with 100 MeV Au swift heavy ions (SHI) at 5 × 1012 ions/㎠ fluence. It is observed that the band gap of the films gets red shifted after annealing and irradiation from pristine (as deposited) films. In addition, there is an increase in the grain size of the films due to both annealing and irradiation, leading to the decrease in resistivity and increase in thermoemf of the films. These results were explained in the light of thermal spike model.
Electron-Electron Interactions based Metal-Insulator Transition in Ga Doped ZnO Thin Films
R V Muniswami Naidu,A Subrahmanyam,A Verger,M K Jain,S V N Bhaskara Rao,S N Jha,D M Phase 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.4
We report on the charge carrier transport mechanisms of undoped and Ga doped (2 wt. % and 4 wt. %)ZnO thin films grown by pulsed dc magnetron sputtering technique. Temperature dependent resistivity measurements showed typical semiconducting behaviour for undoped ZnO thin films where as Ga doped ZnO thin films showed metallic nature at higher temperatures and insulating nature with a metal to insulator transition at lower temperatures. The observed transition temperatures are 91 K and 140 K for 2 wt. % and 4 wt. %Ga doped ZnO films respectively. The observed metal insulator transition is attributed to the electron-electron interactions at low temperatures. The variations in the transition temperatures are explained based on the disorderness induced in the system due to the doping effect. ZnO doped with 4 wt. % Ga showed the lowest resistivity of 5.7 × 10−4Ω cm with a carrier concentration of 1.2 × 1021/cm3. Undoped and doped ZnO thin films are about 90% transparent in the visible region. Blue shift is observed in the absorption edge with the effect of doping and it is explained based on B-M shift. The Fermi level measured from valance band spectroscopy showed a shift of +0.6 eV for 2 wt. % Ga doped ZnO thin film and +0.7 eV for 4 wt. %Ga doped ZnO thin film compared to the Fermi edge of undoped ZnO thin films. This ascertains the movement of Fermi level in to the conduction band with the effect of doping.