MAMR – Microwave-Assisted Magnetic Recording. This is a way of overcoming the thermal stability limitations of current Perpendicular Magnetic Recording (PMR) technology used in disk drives. PMR bits become unstable as their size shrinks below the 2TB/platter areal density point. MAMR records bits in a more stable but resistant recording medium, which needs beamed microwave energy to assist the read/write heads in writing bits.
A MAMR-equipped write head has a main writing pole which projects magnetic energy or flux at the platter recording medium when it needs to write a bit. There is a space between the main pole and a trailing shield. A tiny Spin Torque Oscillator (STO) is inserted into this space. The STO has two components: a microwave Field Generation Layer (FGL) and a Spin Injection Layer (SIL).