Journal of the Korean Vacuum Society (한국진공학회지)

The Korean Vacuum Society (한국진공학회)
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The Characterization of Nb3Ge by Slow Positron Annihilation Spectroscopy

저에너지 양전자 소멸 분광법을 이용한 Nb3Ge 박막 특성

  • Lee, C.Y. (Department of Physics, Hannam University) ;
  • Bae, S.H. (Department of Radiological Science, Konyang University)
  • Received : 2010.08.25
  • Accepted : 2010.10.30
  • Published : 2010.11.30
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Abstract

Enhance signal-to-noise ratio, slow positron coincidence Doppler Broadening method has been applied to study of characteristics of $Nb_3Ge$ superconductor film, which were performed from 20 K to 300 K sample temperature near Tc of it. In this investigation the numerical analysis of the Doppler spectra was employed to the determination of the shape parameter, S, defined as the ratio between the amount of counts in a central portion of the spectrum and the total counts of whole spectrum. The S-parameter values between 0.598 and 0.594 were decreased while the temperature were decreasing, that indicated the voids into the samples. The temperature dependence came from specific positron trapping rate into the vacancy-type defects. It is believed that the positrons annihilate with normal-electrons instead of super-electrons in the Nb3Ge superconductor.

저속 에너지 도플러 넓어짐 양전자 소멸 분광법으로 $Nb_3Ge$ 시료내의 원자 크기 정도 고체 구조 특성에 대하여 조사하였다. A15 화합물 구조로 된 $Nb_3Ge$ 시료를 상온에서 초전도 특성을 갖는 상전이 온도 근처의 S-변수를 측정하였다. 양전자와 전자의 쌍소멸로 발생하는 511 keV 감마선 스펙트럼의 수리적 해석 방법인 S-변수를 사용하여, 상전이 근처 온도에서 박막의 구조 변화를 측정하였다. 양전자의 입사 에너지에 따른 S-변수는 0.598에서 0.594로 온도의 변화에 의하여 감소하였으며 이때 초전도 전이와는 무관함을 나타낸다. 고온으로 갈수록 일반적인 트랩핑 비율은 커지고 양전자 흐름은 공공(voids) 근처에서 소멸하는 것이 보였다. 이 결과로부터 양전자가 초전자와 소멸하기 보다는 상전자와 소멸하는 것으로 판단된다.

Keywords

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