The Magnetic Hard Disk Drive - How Information is Stored in the Cloud

More than 70 percent of the world's information is stored in Hard Disk Drives (HDDs) and this is expected to continue to be true over the next decade despite competition from NAND flash memory. HDDs have the attributes of extremely high capacity at low cost (10x lower than NAND), high data rate (GHz), non-volatility, and reasonable access time (ms). The bit areal density growth of HDDs has often exceeded Moore's Law over the last 60 years resulting in more than a 200 million fold increase. A survey of the various technologies used in HDDs reveals a nanotechnology "playground" for physicists that exists today. For example: 6 nm diameter magnetic grains covered by 2 nm of diamond-like carbon and 1 nm of specially crafted lubricant, bit pitch of 10 nm, sub-25 nm wide magneto-resistive sensors with 1nm tunneling gap (the basic physics of which resulted in the 2007 Nobel Prize), airfoils than maintain a sub-2 nm gap between the head and disk while flying at up to 100 mph under a variety of environmental conditions, and mechanical actuators than can move the head to a desired position on the disk with sub-nanometer precision in only a few milliseconds. In this talk I will describe the physical limits of HDD technology and some ways the industry is pushing these limits further, such as hermetically-sealed helium HDDs and by using near-field energy sources such as plasmonic antennas and spin-torque oscillators.