One of {HEAD ~ the magnetic layers} may be a so called granular structure in which {TAIL ~ a magnetic material} is dispersed 
One of { HEAD ~ the magnetic layers } may be a so called granular structure in which { TAIL ~ a magnetic material } is dispersed
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH