Flux distribution in Fe-based superconducting materials by magneto-optical imaging

نویسندگان

  • Zhi Wei Lin
  • Jian Guo Zhu
  • Guang Guo
  • Xiaolin Wang
  • S X. Dou
  • Jian Guo
  • Tom H. Johansen
  • Xun Shi
  • Xiao Lin Wang
  • Shi Xue Dou
چکیده

This paper presents the magnetic flux distributions in Fe-based superconducting materials including single crystal of Ba(Fe1.9Ni0.1)As2 and Ba(Fe1.8Co0.2)As2, as well as polycrystalline SmFeO0.75F0.2As by means of magneto-optical imaging (MOI) technique. The single crystals were grown out of FeAs flux while polycrystalline sample was grown by hot-press. A MOI film with in-plan magnetization was used to visualize flux distributions at the sample surface. A series of magneto-optical images was taken when the samples were zero-field cooled and field cooled. The flux behavior, including penetration into and expelling from the samples, as well as pinning properties were studied. When external fields increase, flux is completely shielded from the crystals, then, gradually penetrates toward the crystal center from the edge. For polycrystalline sample, Meissner state was observed at very low field. With increasing the field further, flux penetrates into the sample easily along grain boundary, then into grain. Compared with high-Tc cuprates, it is found that the flux distributions in Fe-based superconducting materials are very similar to that in high-Tc cuprates with strong pinning strength.

برای دانلود رایگان متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Magneto-optical imaging of magnetic flux patterns in superconducting films with antidots

We present the results of experiments on visualization of magnetic flux distribution and its dynamics in high-temperature superconductors with artificial defects. High-Tc superconductor thin films were equipped with a special arrangement of antidots in order to separate the streams of magnetic flux moving in (or out of) the sample. A possibility to alter the direction and depth of flux penetrat...

متن کامل

High sensitivity differential magneto-optical imaging with a compact Faraday-modulator.

We present here the design of a sensitive compact Faraday-modulator (CFM) based optical magnetometer for imaging the distribution of weak local magnetic fields inside hysteretic magnetic materials. The system developed has a root-mean-square noise level of 50 mG Hz(-1/2) at a full frame rate of 1 fps (frame per second) with each frame being of size 512 × 512 pixels. By measuring the local magne...

متن کامل

Magneto Optical Studies of Ybco Thick Films in the Critical State

We present magneto optical studies of the critical state in YBa2Cu3O7-δ (YBCO) thick films prepared using BaF2 ex-situ post reaction process. A fractal-like propagation was observed as the magnetic flux entering the superconducting films, in striking contrast to the behavior expected of a uniform type II superconducting film in the critical state. However, by averaging the flux density over a c...

متن کامل

Flux distribution in superconducting films with holes

Flux penetration into type-II superconducting films is simulated for transverse applied magnetic field and flux creep dynamics. The films contain macroscopic nonconducting holes, and we introduce the holes in the simulation formalism by reconstruction of the magnetic field change inside the holes. We find that the holes induce a region of reduced flux density extending toward the nearest sample...

متن کامل

Large area magneto-optical investigations of YBCO thin films

A new apparatus for magneto-optical investigations of high temperature superconducting ~HTS! films as large as 20320 cm is presented. With this equipment flux penetration of an external magnetic field into YBCO thin films has been studied by scanning the samples through an inhomogeneous magnetic field ~magneto-optical scanning technique, MOST!. The normal penetration of magnetic flux into a sup...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2017