Tunneling magnetoresistive heads for magnetic data storage.

Area of Science:

• Spintronics and Nanotechnology
• Condensed Matter Physics
• Materials Science

Background:

• Spintronics leverages electron spin for novel applications beyond charge-based electronics.
• Magnetic tunnel junctions (MTJs) are key spintronic devices with industrial relevance.
• Spin-dependent tunneling transport is a fundamental phenomenon in spintronics.

Purpose of the Study:

• To review the fundamental physics and materials of magnetic tunnel junctions.
• To detail the application of magnetic tunneling devices in magnetic data storage.
• To highlight the performance and advantages of tunneling magnetoresistive (TMR) reading heads.

Main Methods:

• Review of basic physics and materials for MTJs.
• Analysis of TMR head performance in hard disk drives (HDDs).
• Comparison of TMR heads with giant magnetoresistive (GMR) devices.

Main Results:

• First-generation TMR heads achieved 80-100 Gbit/in² areal density in Seagate HDDs.
• TMR heads provided 3x larger signal amplitude and 0.6 decade BER gain over GMR.
• Improved thermal dissipation, lifetime, and robustness demonstrated for TMR heads.
• Areal densities of 274 Gbit/in² and 311 Gbit/in² achieved with TMR heads and perpendicular media.

Conclusions:

• TMR heads are a mature and capable reader technology for HDDs.
• TMR technology has enabled significant increases in data storage density.
• TMR heads are a mainstream and preferred technology for current and future HDD products.