An international team of researchers has introduced the world’s smallest magnet. They have demonstrated that it’s possible for using that magnet which is an individual atom.
This magnet consisting of single atom will be used for storing single bit of data.
This research was led by teams at the IBM Research Almaden and Ecole Polytechnique Federale de Lausanne (EPFL) in Switzerland. Until this research molecules were the smallest ever data storing units.
Single Atom as Storage unit:
One can think about it like with a single bit per atom, it would be conceivable to store entire iTunes library of 35 million songs on a device which is no bigger than a credit card.
Latest research stems from work in which IBM developed an electron-spin resonance (ESR) sensor. It consisted of a single iron atom over the tip of a scanning tunneling microscope (STM).
STMs can detect the tunneling of electrons between the ultra-sharp probes as it’s scanned across the surface. It was when it combined with the iron atom which can measure the magnetic field of an atom more directly.
It can even provide greater sensitivity than any other method.
Now we know that what the scientists have been using their newly developed iron-atom sensor. It is for detecting the magnetic fields of holmium atoms.
These atoms come from a family of rare earth metals which are known for their higher level of magnetism.
Prior to the development of the iron-atom sensor, there didn’t appear to be a way over both read and manipulate pole. It include those of holmium atoms while using only an STM without disrupting it.
Source: IBM Research – YouTube
Combination of STM:
By means of being able to read the holmium atoms magnetic pole with the iron atom, they can be used to store the zeros.
They can even be the ones which can be used in digital logic. In essence of that, researchers has developed a read-write method for storing data over a single atom.
It includes in combination of an STM with an iron atom which serves as an ESR sensor. Latest research which is described in the journal Nature, they have found where they could place iron atom within a nanometer of holmium atom.
Thus, the iron atom could read the north and south of its magnetic poles. It can be done without the sensor atom getting affected by the electric current. It can turn the holmium atom’s magnetic state from north to south.
As iron and holmium atom can be spaced so closely, it’s conceivable that engineers could create dense magnetic storage. They will be thousand times as dense as today’s hard disk drives and solid state memory chips.
Arrangement of an single atom, read-write memory storage system starts by means of placing atoms over an substrate. This substrate consists of magnesium oxide which serves as an insulating layer. This layer will be between the metal electrodes beneath it and magnetic atoms over its top.
Holding Polarization over Magnet:
Holmium atoms will be holding its polarization for longer time under many conditions. These conditions include presence of magnets while making it ideal for data storage medium. It is further attached to this magnesium oxide surface.
When this tip of the STM is introducing current to holmium atom, it flips its magnetic poles of atom. It ultimately changes its state from 1 to 0 or vice versa.
This step more or less corresponds to the write process in the hard disk drive. Read process involves the iron atom detecting the magnetic state of the holmium atom.
This can be further achieved by means of exploiting a phenomenon which is called “precess”. When these atoms which are having unpaired electron spins are placed in magnetic field they will rotate around the magnetic field. This rotation will be at a precise frequency.
Frequency obtained depends upon the field strength and atom’s magnetic moment which is the strength of the atom’s magnetization. Researchers are applying a magnetic field to microscope and then a high frequency voltage to the tunnel junction of STM.
When frequency of the voltage matches the frequency of spin possession, spin is driven away from its thermal equilibrium. It was aligned primarily with the magnetic field. Iron sensor over the tip of the STM detects this change in orientation.
It is mainly because of the sweeping of frequency through the resonance frequency. Thus making for a sharp change in tunnel current which appears exactly at the resonant frequency. Resonance frequency moves in response to the nearby magnetic atoms.
Chris Lutz is a staff scientist at IBM Almaden as explained to IEEE Spectrum during earlier part of this week. He says that the physical principle is same as that of the magnetic resonance imaging. Except that they detects electron precession instead of nuclear precession.
Even they are addressing individual atoms instead of billions of them. It is by means of positioning the tip over the atom of interest. Lutz cautions that we shouldn’t be expecting this technology for replacing our computer hard drives anytime soon.
STM’s which perform this work have to be kept at four degree Kelvin in order to keep the atoms from moving around. It was obviously not going to be possible for a mobile handset in one’s pocket.
Even there is a long list of scientific and engineering steps which looms ahead such as manufacturability.
It said that Lutz and his team are clearly enthusiastic regarding the prospects that their latest research has tuned up. Few years ago, they looked at this class of magnetic atoms only for getting disappointed that they couldn’t do much with them.
Reason for that included that their electron structure made it difficult for the STMs for working with them. Now with the discovery of their newer ESR sensor in form of single iron atom, possibilities seems to be endless.
It’s quite too early to tell whether it will ultimately lead to a newer type of computer data storage. Yet the journey might yield many more of those breakthroughs than just computer memory.