“Spin Ice” promises a breakthrough in magnetic technology affecting both mass storage and energy conservation, according to the online journal Nature Communication. Researchers at London Centre for Nanotechnology(LCN), working with teams of scientists from Oxford and Cambridge Universities, are delving into the field of low temperature physics. Their preliminary findings confirm a previously unknown reaffirmation of the Third Law of Thermodynamics and suggest possibilities for significant improvements for mass storage devices, among other applications.
Broken down into layman’s terms, this “new” technology may make it possible to “transmit” magnetic fields in much the same way that electricity is transmitted through ordinary copper wires. Meaningful applications of this new technology may make it possible to store much larger amounts of data on computer hard drives, as well as faster operating systems deriving from the direct application of magnetic energy to store and retrieve data.
In a standard mass storage device, electrical impulses are converted into magnetic pulses, which are stored on the “plates” or “platters” inside the hard drive. Those plates are thin disks of aluminum or glass impregnated with a very thin ferrous oxides to create a magnetically sensitive surface. When saving data, a recording head passes over the surface of the plates leaving a pattern of charged and uncharged particles behind on the molecular level. When retrieving data, a second playback head passes over the surface of the plate and the magnetic impulses stored on the plate trigger minute pulses of electricity in the playback head. The computer system then converts that binary code into meaningful data.
This is a layman’s version of how all of the electronic data in existing computer devices (except solid state devices) is stored and retrieved. Spin ice promises, eventually, to revolutionize mass storage devices by using very thin plastic films impregnated with some very esoteric compounds bonded to a non-reactive substrate. When cooled to within one degree of Absolute Zero (-459.67 Fahrenheit or -273.15 Celsius), the entropy level for all other substances is essentially zero…no movement within the atoms or molecules….but spin ice molecules still have spin, hence the name spin ice. They do not reach the zero entropy state, until they reach the very closest threshold to true absolute zero, within 5/100ths of a degree, when the zero entropy state was observed.
This research confirms an observation made by Dr. Linus Pauling who, in 1935, noted that molecules in water ice showed a degree of freedom that would theoretically allow water molecules to remain “disordered” even at absolute zero. Pauling suggested that the residual entropy demonstrated found in regular ice was due to the unique structure of the water molecule, with each molecule having one atom of hydrogen bonded to two atoms of oxygen. Hydrogen, it seems, is not monogamous. The same hydrogen atom is likely to be attracted to the oxygen atoms of an adjacent hydrogen atom, giving up its attachment to the two oxygen atoms it was keeping company with. This causes the spin phenomenon as the atoms of adjacent water molecules exchanged atoms in a random behavior pattern.
The “spin ice” used in this research isn’t really water ice, but it behaves the same way under near absolute zero conditions.
The unique property that makes this interesting to scientists and engineers is that spin ice seems to be a magnetic monopole, a magnetic field having only one pole. Common magnets are always bipolar, having a negative and a positive pole. This is demonstrated with iron filings. If you move the positive pole of a magnet under a sheet of paper covered with iron filings, the iron filings will be attracted to the magnet. f you move the negative pole of the same magnetic under the paper the iron filing will move away from the magnetic field. If you cut the magnet in half, each half will still have a positive and negative pole.
There are some applications in electricity for which a bipolar magnet is absolutely essential. There are others in which a monopole magnet might be much better. Bipolar magnetism used in recording devices often have problems with the echoes or ghost images caused by the opposite pole to the one being used to record data on the recording medium. With a monopole magnet device, it may be possible transmit data more quickly by a simple process of “tapping” the substrate to perturb the system. It is thought that the deformation of the substrate generates sufficient heat energy to spike the temperature within the film. This could possibly turn the monopole characteristic on and off, creating a “writing” device that could operate more quickly.
“Spin ice” wafers may be used – someday – in a variety of mass storage devices by applying strain-producing deformation on the substrate material, which appears to cause spikes n the entropy of the film that would affect the magnetic monopole environment. Anything that can predictably create a specific result in terms of changing the magnetic potential on a film of this nature could conceivably be used to store and retrieve data.
“Spin Ice” promises to offer breakthrough technology, but it won’t be on store shelves for quite some time yet. Nevertheless, Dr. Pauling would be pleased to see how his speculations are bearing fruit eighty years later. Genius is often a matter of dates.
By Alan M. Milner (@alanmilner on twitter)