29-01-2013, 12:07 PM
Pixie Dust
1Pixie Dust.docx (Size: 237.96 KB / Downloads: 18)
INTRODUCTION
In each of the past five years, hard drive capacities have doubled, keeping storage costs low and allowing technophiles and PC users to sock away more data. However, storage buffs believed the rate of growth could continue for only so long, and many asserted that the storage industry was about to hit the physical limit for higher capacities. But according to IBM, a new innovation will push back that limit. The company is first to mass-produce computer hard disk drives using a revolutionary new type of magnetic coating that is eventually expected to quadruple the data density of current hard disk drive products -- a level previously thought to be impossible, but crucial to continue feeding the information-hungry Internet economy. For consumers, increased data density will help hasten the transition in home entertainment from passive analog technologies to interactive digital formats.
The key to IBM's new data storage breakthrough is a three-atom-thick layer of the element ruthenium, a precious metal similar to platinum, sandwiched between two magnetic layers. That only a few atoms could have such a dramatic impact caused some IBM scientists to refer to the ruthenium layer informally as "pixie dust". Known technically as "antiferromagnetically-coupled (AFC) media," the new multilayer coating is expected to permit hard disk drives to store 100 billion bits (gigabits) of data per square inch of disk area by 2003. Current hard drives can store 20 gigabits of data per square inch. IBM began shipping Travelstar hard drives in May 2001 that are capable of storing 25.7 gigabits per square inch. Drives shipped later in the year are expected to be capable of 33% greater density. In information technology, the term "pixie dust" is often used to refer to a technology that seemingly does the impossible.
CONVENTIONAL MEDIA
BASICS OF MAGNETIC RECORDING
Read-Rite's recording heads are the miniaturized hearts of disk drives and other magnetic storage devices. While they may appear to be simple components, their design and manufacture require leading-edge capabilities in device modeling, materials science, photolithography, vacuum deposition processes, ion beam etching, reliability testing, mechanical design, machining, air bearing design, tribology, and other critical skills.
Writing Magnetic Data
Simplified sketches of a writing head are shown in Figure1. The view from the top of the writing head (left) shows a spiral coil wrapped between two layers of soft magnetic material; on the right is a cross-section of this head as viewed from the side. Note two things in this figure: at the lower end, there is a gap between these layers, and at their upper end these layers are joined together. The top and bottom layers of magnetic material are readily magnetized when an electric current flows in the spiral coil, so these layers become North and South magnetic poles of a tiny electromagnet. [In a real head, the distance from the gap to the top of the coil is about 30 microns (or 0.0012 inch).]
Reading Magnetic Data
In the case of Read-Rite's leading edge products, recording heads read magnetic data with magnetically sensitive resistors called Spin Valves which exploit the GMR Effect. These GMR/Spin Valve heads are placed in close proximity to a rotating magnetized storage disk, thereby exposing the GMR element to magnetic bit fields previously written on the disk surface. If a GMR head is moved only slightly away from the disk (perhaps 2 to 3 millionths of an inch) the field strength drops below a useful level, and magnetic data cannot be faithfully retrieved.
SUPERPARAMAGNETIC EFFECT
Computers get better and better, faster and faster; and, of all computer components, probably the greatest rate of evolution belongs to the stalwart hard drive. On a daily basis, the storage capacity and speed of hard drives increases, while their cost just keeps on shrinking. This is one of those rare situations in which both consumers and companies profit; but something called superparamagnetic effect may soon bring an end to this golden age.
As hard drives become capable of storing more information and accessing it at faster speeds, their data becomes more susceptible to corruption. This data-density barrier is known as the superparamagnetic effect (or SPE). Before going on to say more about SPE, though, it might be helpful (and scenic) to take a brief detour to examine the technology at the hub of your average hard drive.
Today's hard drive resembles a small record player that's capable of stacking its disks, or platters, to hold up to eight of them at a time. Each platter is covered with a magnetic film that is ingrained with tiny particles called bits. When a read-write head (looking like the needle of a record player) passes over the bits, it either magnetically aligns the particles to record information (turning them into series of 1's and 0's), or it reads them in order to access previously-stored data. These operations take place at phenomenal speeds; the platters spin around thousands of times per minute, and both sides of them are scanned simultaneously by read-write heads.
AFC MEDIA
Antiferromagnetically coupled media
Antiferromagnetically Coupled (AFC) media (synthetic ferrimagnetic media (SFM) or Laminated Antiferromagnetically Coupled (LAC) media) technology is expected to extend the lifetime of longitudinal magnetic recording technology. LAC media differ from the conventional media by their structure and functionality. Conventional recording media have one or more magnetic layers, which may be coupled ferromagnetically to each other. In AFC media, there are at least two magnetic layers, but the magnetic layers are coupled antiferromagnetically. In comparison to conventional media, AFC media exhibit similar or better recording performance. But, at the same time, AFC media show much improved thermal stability, which makes them attractive.
CONCLUSION
Because of advances in disk technology, like IBM's pixie dust, we can expect to see 400GB desktop drives and 200GB notebook drives within another year or so, according to IBM scientists. Fujitsu is using similar technology. Fujitsu's SF Media uses a recording medium made up of two magnetic layers separated by a thin layer of ruthenium. In summary, IBM has developed and is now mass-producing a promising new disk-drive media technology based on antiferromagnetically coupled multilayers that can enable significant areal density increases while maintaining the thermal stability of recorded data. This advancement will permit magnetic hard-disk drive technology to extend far beyond the previously predicted "limits" imposed by
the superparamagnetic effect.
1Pixie Dust.docx (Size: 237.96 KB / Downloads: 18)
INTRODUCTION
In each of the past five years, hard drive capacities have doubled, keeping storage costs low and allowing technophiles and PC users to sock away more data. However, storage buffs believed the rate of growth could continue for only so long, and many asserted that the storage industry was about to hit the physical limit for higher capacities. But according to IBM, a new innovation will push back that limit. The company is first to mass-produce computer hard disk drives using a revolutionary new type of magnetic coating that is eventually expected to quadruple the data density of current hard disk drive products -- a level previously thought to be impossible, but crucial to continue feeding the information-hungry Internet economy. For consumers, increased data density will help hasten the transition in home entertainment from passive analog technologies to interactive digital formats.
The key to IBM's new data storage breakthrough is a three-atom-thick layer of the element ruthenium, a precious metal similar to platinum, sandwiched between two magnetic layers. That only a few atoms could have such a dramatic impact caused some IBM scientists to refer to the ruthenium layer informally as "pixie dust". Known technically as "antiferromagnetically-coupled (AFC) media," the new multilayer coating is expected to permit hard disk drives to store 100 billion bits (gigabits) of data per square inch of disk area by 2003. Current hard drives can store 20 gigabits of data per square inch. IBM began shipping Travelstar hard drives in May 2001 that are capable of storing 25.7 gigabits per square inch. Drives shipped later in the year are expected to be capable of 33% greater density. In information technology, the term "pixie dust" is often used to refer to a technology that seemingly does the impossible.
CONVENTIONAL MEDIA
BASICS OF MAGNETIC RECORDING
Read-Rite's recording heads are the miniaturized hearts of disk drives and other magnetic storage devices. While they may appear to be simple components, their design and manufacture require leading-edge capabilities in device modeling, materials science, photolithography, vacuum deposition processes, ion beam etching, reliability testing, mechanical design, machining, air bearing design, tribology, and other critical skills.
Writing Magnetic Data
Simplified sketches of a writing head are shown in Figure1. The view from the top of the writing head (left) shows a spiral coil wrapped between two layers of soft magnetic material; on the right is a cross-section of this head as viewed from the side. Note two things in this figure: at the lower end, there is a gap between these layers, and at their upper end these layers are joined together. The top and bottom layers of magnetic material are readily magnetized when an electric current flows in the spiral coil, so these layers become North and South magnetic poles of a tiny electromagnet. [In a real head, the distance from the gap to the top of the coil is about 30 microns (or 0.0012 inch).]
Reading Magnetic Data
In the case of Read-Rite's leading edge products, recording heads read magnetic data with magnetically sensitive resistors called Spin Valves which exploit the GMR Effect. These GMR/Spin Valve heads are placed in close proximity to a rotating magnetized storage disk, thereby exposing the GMR element to magnetic bit fields previously written on the disk surface. If a GMR head is moved only slightly away from the disk (perhaps 2 to 3 millionths of an inch) the field strength drops below a useful level, and magnetic data cannot be faithfully retrieved.
SUPERPARAMAGNETIC EFFECT
Computers get better and better, faster and faster; and, of all computer components, probably the greatest rate of evolution belongs to the stalwart hard drive. On a daily basis, the storage capacity and speed of hard drives increases, while their cost just keeps on shrinking. This is one of those rare situations in which both consumers and companies profit; but something called superparamagnetic effect may soon bring an end to this golden age.
As hard drives become capable of storing more information and accessing it at faster speeds, their data becomes more susceptible to corruption. This data-density barrier is known as the superparamagnetic effect (or SPE). Before going on to say more about SPE, though, it might be helpful (and scenic) to take a brief detour to examine the technology at the hub of your average hard drive.
Today's hard drive resembles a small record player that's capable of stacking its disks, or platters, to hold up to eight of them at a time. Each platter is covered with a magnetic film that is ingrained with tiny particles called bits. When a read-write head (looking like the needle of a record player) passes over the bits, it either magnetically aligns the particles to record information (turning them into series of 1's and 0's), or it reads them in order to access previously-stored data. These operations take place at phenomenal speeds; the platters spin around thousands of times per minute, and both sides of them are scanned simultaneously by read-write heads.
AFC MEDIA
Antiferromagnetically coupled media
Antiferromagnetically Coupled (AFC) media (synthetic ferrimagnetic media (SFM) or Laminated Antiferromagnetically Coupled (LAC) media) technology is expected to extend the lifetime of longitudinal magnetic recording technology. LAC media differ from the conventional media by their structure and functionality. Conventional recording media have one or more magnetic layers, which may be coupled ferromagnetically to each other. In AFC media, there are at least two magnetic layers, but the magnetic layers are coupled antiferromagnetically. In comparison to conventional media, AFC media exhibit similar or better recording performance. But, at the same time, AFC media show much improved thermal stability, which makes them attractive.
CONCLUSION
Because of advances in disk technology, like IBM's pixie dust, we can expect to see 400GB desktop drives and 200GB notebook drives within another year or so, according to IBM scientists. Fujitsu is using similar technology. Fujitsu's SF Media uses a recording medium made up of two magnetic layers separated by a thin layer of ruthenium. In summary, IBM has developed and is now mass-producing a promising new disk-drive media technology based on antiferromagnetically coupled multilayers that can enable significant areal density increases while maintaining the thermal stability of recorded data. This advancement will permit magnetic hard-disk drive technology to extend far beyond the previously predicted "limits" imposed by
the superparamagnetic effect.