In {HEAD ~ related embodiments} of {TAIL ~ the invention}, at least one recessed region is positioned at a magnetic pole 
of
In { HEAD ~ related embodiments } of { TAIL ~ the invention } , at least one recessed region is positioned at a magnetic pole
OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH