2023: Heat assisted magnetic recording (HAMR) finally arrives

Heat assisted magnetic recording (HAMR) finally arrives

 

 

 

After decades of 40% compound annual growth rate (CAGR) in areal density, single digit CAGR’s have prevailed since about 2010. Perpendicular Magnetic Recording technology by itself has nearly reached its limit in areal density near 1.2 Tbpsi in 2023 (2014: HDD AREAL DENSITY REACHES 1 TERABIT/SQ. IN.). Higher HDD capacities (more bytes in the box) were achieved mainly through putting more, slightly larger disks in the drive enabled by the use of helium in place of air (2013: HELIUM DRIVES CLOUD STORAGE). Head technology also continued to advance with two-dimensional magnetic recording (TDMR - using dual readers), shingled magnetic recording (SMR), passing a bias current through the pole tips and inserting a spin-torque layer between the pole-tips, as well as multiple head-disk lower spacing enablers (including separate read and write heaters and touch down sensors). None of these technologies allowed substantial growth in areal density.

As areal density increased and bit sizes became smaller, it became harder for the bits to remain stable. They might spontaneously flip vertical orientation changing from zero to one or vice versa, corrupting the written data. To remain stable the difficulty of flipping the bits (the coercivity of the magnetic media) must be increased, however the head field available to write the bits is limited by the materials available. But there is a solution. All magnetic materials have a Curie temperature, above which they are only weakly magnetic. The trick is to heat, and cool, only the very tiny volume of the bit to be written and to do so very, very quickly, typically in under a nanosecond. Learning to successfully and reliably do this in a commercial product has taken decades.

As early as 1954, engineers working for RCA filed a patent which described the basic principle of using heat in conjunction with a magnetic field to record data. Various companies tried to commercialize this technology over the years with limited commercial success. In the late 1990’s Seagate began work on the technology and finally showed a prototype at the Magnetic Recording Conference in 2012. Commercialization however proved difficult. At the January 2019 Consumer Electronics Show (CES), Seagate showcased HAMR technology but it was not until 2022 that qualification samples were actually seen by select customers. 20-24 TB heat assisted magnetic recording (HAMR) hard drives are shipping today with 32 TB HAMR drives announced by Seagate for Q3 this year and 50 TB by 2026. Future areal density growth will depend on the further development of HAMR as well as new technologies such as next generation TDMR and heated dot magnetic recording.