A perpendicular spin transfer torque MRAM memory cell includes a magnetic tunnel junction that has a free layer, a pinned layer and a tunnel barrier between the free layer and the pinned layer. The free layer has a switchable direction of magnetization perpendicular to the plane of the free layer. A cap layer is provided adjacent to the magnetic tunnel junction. The thickness of the cap layer is increased so that the cap layer acts as a heating layer, which results in a reduction of the current density during writing and increases the write margin. In some embodiments, a resistive heating layer is added to the memory cell, adjacent to the cap layer, in order to achieve the lower current density and increased write margin while also improving signal to noise ration during reading by eliminating shot noise.