Domain Wall Assisted Magnetic Recording
  Using numerical and analytical micromagnetics we calculated the switching fields and energy barriers of the composite (exchange spring) magnetic recording media, which consist of layers with high and low magnetocrystalline anisotropy. We demonstrate that the ultimate potential of the composite media is realized if the interfacial domain wall fits inside the layers. The switching occurs via domain wall nucleation, compression in the applied field, de-pinning and propagation through the hard/soft interface. This domain wall assisted switching results in a significant reduction of the switching field without substantial decrease of the for thermal activation energy barrier. We demonstrate that the Domain Wall Assisted Magnetic Recording (DWAMR) offers up to a three-fold areal density gain over conventional single layer recording. 
A. Yu. Dobin and H. J. Richter