A bottom pinned perpendicular magnetic tunnel junction (pMTJ) with high TMR which can withstand high temperature back-end-of-line (BEOL) processing is disclosed. The pMTJ includes a composite spacer layer between a SAF layer and a reference layer of the fixed magnetic layer of the pMTJ. The composite spacer layer includes a first non-magnetic (NM) spacer layer, a magnetic (M) spacer layer disposed over the first NM spacer layer and a second NM spacer layer disposed over the M layer. The M layer is a magnetically continuous amorphous layer, which provides a good template for the reference layer.