A magnetic device for magnetic random access memory (MRAM), spin torque MRAM, or spin torque oscillator technology is disclosed wherein a perpendicularly magnetized magnetic tunnel junction (p-MTJ) with a sidewall is formed between a bottom electrode and a top electrode. A first dielectric layer is 3 to 400 Angstroms thick, and formed on the p-MTJ sidewall with a physical vapor deposition RF sputtering process to establish a thermally stable interface with the p-MTJ up to temperatures around 400° C. during CMOS fabrication. The first dielectric layer may comprise one or more of B, Ge, and alloys thereof, and an oxide, nitride, carbide, oxynitride, or carbonitride. The second dielectric layer is up to 2000 Angstroms thick and may be one or more of SiOYNZ, AlOYNZ, TiOYNZ, SiCYNZ, or MgO where y+z>0.