Figure 4

Measured polarized DFI of the sintered NdFeB magnet. (a) TI and DFI images of the NdFeB with and without the external magnetic field at \(\xi \simeq 0.7 \upmu \hbox {m}\) and without analyzer in place. The North and the South poles of the applied field are depicted in red and blue, respectively. (b) DFI experimental values and the fitted \(\frac {V_s(\xi )}{V_0}\) curves based on model of correlation functions \(G(\xi )\) for the four configurations without the external magnetic field corresponding to the \(V^{++}\), \(V^{-+}\), \(V^{+}\) and \(V^{-}\). (c) DFI experimental values and the fitted DFI curves with the extracted correlation functions \(G(\xi )\) for the four configurations with the external magnetic field corresponding to the \(V^{++}_{H}\), \(V^{-+}_{H}\), \(V^{+}_{H}\) and \(V^{-}_{H}\). The modeled \(G(\xi )\) functions were based on the description of random two phase media. The magnetization easy axis of the sample is along the short side of the sample and along the applied external magnetic field.