Cutting-edge HDD Head Technologies are Supporting the Digital Transformation (DX) of Society

HDDs are the High-Capacity, Low-Cost Data Storage Solution for the DX Era

Today, a plethora of data is generated by individuals, businesses, IoT devices and sensors, sent through the Internet, and recorded for subsequent use. Generally, digital data is recorded on HDDs and solid-state disks (SSDs). While SSDs—which are based on flash memory and feature high speeds and low power consumption—are now widely used in personal computers; HDDs—with their large capacities and superior cost per bit (cost per amount of data recordable)—play a leading role in near-line storage^*1 used in data centers. With the growth of 5G communications and IoT devices and the emergence of edge computing^*2, the amount of data that needs to be stored in data centers will continue to increase—which, in turn, is expected to drive the need for HDDs even further.

The amounts of digital data generated annually worldwide

Source: Data Age 2025, IDC (Graph created by TDK)

The annual amount of data generated worldwide is expected to increase to 175ZB (one zettabyte (ZB) equals one billion terabytes (TB), which equals 1,000 gigabytes (GB), which equals 1,000,000 megabytes (MB)) by 2025.

The Evolution of HDD Recording Technologies, Enabled by Magnetic Heads

The capacity of HDDs has increased hand-in-hand with the proliferation of personal computers, beginning with just a few tens of megabytes in the 1980s, to typically several terabytes in the 2020s—exceeding a hundred thousand-fold increase. A key factor that enabled this dramatic increase in capacity is the technological innovations behind the magnetic head, which reads and writes data in HDDs.

TDK has long been a leading manufacturer of HDD magnetic heads, developing innovative head technologies over the years. In 1987, we developed the thin-film magnetic head^*3, which significantly increased recording density over conventional heads. In 2005, we commercialized the Perpendicular Magnetic Recording (PMR)^*4 head, which broke the density limitations of Longitudinal Magnetic Recording^*5. The Perpendicular TMR head, which incorporates high-sensitivity TMR technology^*6, has pushed recording densities even further, enabling higher-capacity HDDs.

Inside an HDD with its magnetic heads

The recording density of an HDD has recently surpassed 1Tb/in2 (terabits per square inch). This is equivalent to a trillion magnets lined up inside a single square inch. With such high densities, the size of a recording bit within the recording (magnetic) layer has become so small that writing using current magnetic head technology is approaching the limits of physics.

CTO of Headway Technologies
Moris Dovek

To address this problem, TDK is engaged in the development of two next-generation recording methods. One is Microwave-Assisted Magnetic Recording (MAMR). The other is Heat-Assisted Magnetic Recording (HAMR), which employs lasers. Moris Dovek, CTO of Headway Technologies, a TDK Group company and magnetic head manufacturer, explains why they are working on both of these future methods.

“We are currently developing two technologies, MAMR and HAMR. As the world’s only dedicated manufacturer of HDD heads, we believe we need to be ready with both technologies, because we don’t yet know which one will become mainstream first in the near future.”

The evolution of magnetic recording methods and HDD recording densities

What are MAMR and HAMR, the Next-Generation Recording Technologies in the Spotlight?

As the density of HDDs increases, recording bits become finer, which necessitates higher magnetic coercivity^*7 of the recording bits in order to retain thermal stability. However, when coercivity is increased, the magnetic field from the head becomes insufficient for writing the data, thereby requiring external energy to assist with the writing.

In MAMR, microwaves are emitted from a spin torque element^*8 at the tip of the magnetic head to temporarily weaken the coercivity of the recording bit during recording. HAMR, on the other hand, uses a laser beam to instantaneously heat the recording disc and locally weaken coercivity while recording. These next-generation recording methods are projected to improve the recording density of HDDs to as high as 4Tb/in2, enabling 3.5-inch HDDs with capacities of 40 to 60TB, which is about four times what is available today.

Next-generation magnetic recording technologies, MAMR and HAMR

As the world’s only manufacturer specializing in magnetic heads, TDK supplies them to HDD manufacturers around the world. “Because we work with every HDD manufacturer, each of which has unique needs, we enjoy the benefit of receiving a diversity of performance data and feedback, which enhances our work. With respect to MAMR and HAMR, our position as a researcher in both technologies allows us to cross-pollinate our achievements made in both fields. Ultimately, we are driven by the challenge to continually exceed the expectations of our customers,” said Dovek.

HDDs will continue to evolve as a mainstay of data storage. Through the development of magnetic heads—a key component of HDDs—TDK will continue to play a critical part in the progress of a digital society.