A magnetic tunnel junction (MTJ) structure for a magnetic random access memory (MRAM) is provided. Specifically, an MTJ structure with an amorphous CoFeSiB or NiFeSiB free layer is provided. The free layer is a CoFeSiB single layer, a NiFeSiB single layer, a CoFeSiB/Ru/CoFeSiB SAF layer, or a NiFeSiB/Ru/NiFeSiB SAF layer.