Vortices in Iron Pnictide with MFM

 

Magnetic force microscopy images showing an array of magnetic flux lines (vortices) on an Iron Pnictide sample (Ba1-xKxFe2As2) after cooling in various magnetic fields below the critical temperature to 12 K. The vortices appear as white dots in an approximate hexagonal array. The surface topography is also visible, and the green arrows highlight terrace steps and the red circles show a topographic feature common to both the middle and right-hand images.

Sample courtesy of Prof Hai-Hu Wen, National Laboratory for Superconductivity, Chinese Academy of Sciences. The MFM images were taken in constant height (non-contact) mode on the Nanoscan PPMS-AFM.