Microwave-assisted magnetic recording for next-gen HDDs

October 16, 2017 // By Julien Happich
During an event held at its headquarters in Silicon Valley, HDD manufacturer Western Digital Corp. demonstrated what the company claims to be the world’s first Microwave-Assisted Magnetic Recording (MAMR) hard disk drive, a novel technology aimed to increase data reliability and areal density compared to incumbent Perpendicular Magnetic Recording (PMR) and Shingled Magnetic Recording (SMR) technologies.

Developed by Professor Jimmy Zhu from Carnegie Mellon University, MAMR technology is one of two energy-assisted technologies that Western Digital has been developing for years to increase data reliability.The other energy-assisted technology, specifically, heat-assisted magnetic recording (HAMR) presents new material science and reliability challenges that are not a factor in MAMR.

MAMR technology uses a microwave field generated from a spin torque oscillator (STO) located near the write pole of the head. The STO generates an electromagnetic field that allows data to be written to the perpendicular magnetic media at a lower magnetic field. The magnetic grains on disk are similar to spinning gyroscopes that are stable in either an up or down direction in the absence of an external field. When a sufficient magnetic field is applied in the opposite direction of the current state of the magnets, the polarity flips in the direction of the applied field. Applying an additional field from the STO can flip the magnets more quickly, and at a lower magnetic field. While the theory behind MAMR has been known in the industry, and in academia for many years, producing a manufacture-able head that demonstrates the MAMR effect, was elusive.

From internal testing, Western Digital was able to demonstrate higher gains with MAMR technology than the best PMR heads currently available, showing a promising areal density growth (an estimated average of 15 percent per year). Academic studies also show that MAMR has the capability to extend areal density gains to 4Tb per square inch, and beyond, delivering significantly better gains than drives shipping today (Shingled magnetic recording (SMR) drive gains equal 1,300Gb/in 2, while PMR drive gains equal 1,100Gb/in 2).

Western Digital expects to begin shipping ultra-high capacity MAMR HDDs in 2019 for use in data centers to support “Big Data” applications across a full range of industries. 

Western Digital – www.wdc.com