Intergranular Exchange Coupling in FePt:X:FePt (${\rm X}={\rm B}$, C, ${\rm SiO}_{\rm x}$, Cr and ${\rm TaO}_{\rm x}$) Thin Films for Heat Assisted Magnetic Recording

In this study we quantitatively determined the exchange coupling across B, C, SiO
_x
, Cr and TaO
_x
segregants by measuring the exchange coupling between two FePt layers separated by segregant layers of varying thickness. Our study indicates that the segregant that provides the best exchange break is TaO
_x
; whereas, C is the worst and SiO
_x
, Cr and B are in between. Our data indicates that a segregant intergranular region thicker than 0.8 nm should decouple FePt grains if B, TaO
_x
, SiO
_x
, or Cr are used, but with C, a thickness greater than 1 nm is required.