Have you heard of the element Holmium? In a breakthrough that could revolutionize information storeage researchers at IBM have managed to store data on a single Holmium atom.
Holmium is a chemical element with symbol Ho and atomic number 67. … holmium is a rare earth element … discovered by Swedish chemist Per Theodor Cleve. Its oxide was first isolated from rare earth ores in 1878 and the element was named after the city of Stockholm.
Here’s what it looks like:
Elemental holmium is a relatively soft and malleable silvery-white metal. It is too reactive to be found uncombined in nature, but when isolated, is relatively stable in dry air at room temperature. However, it reacts with water and corrodes readily, and will also burn in air when heated.
Writing on a single atom is a milestone accomplishment.
Innovation in electronics manufacturing is driven by a desire to make devices ever smaller but increasingly powerful. Moore’s Law has seen the power of computer chips double every two years without them growing in size, while data storage plateaued somewhat.
Researchers at IBM successfully coded an individual atom with a binary value of 0 or 1 in what is a major step forward for information storage. Experts in the field have described the research as a “landmark achievement” and said it could be used to increase hard-drive storage density by 1,000 times.
“It’s a landmark achievement,” Sander Otte, a physicist at Delft University of Technology in the Netherlands, told Nature. “Finally, magnetic stability has been demonstrated undeniably in a single atom.”
The researchers were able to imbue two Holmium atoms with separate binary values using a magnetised scanning tunnelling microscope. They then connected them to make a miniscule hard drive with four possible combinations.
With the majority of the data ever produced having been created in the past six years, atomic storage could be vital for reducing the space and energy used in keeping information.
If the system was scaled up it would be possible to store an iTunes library of 35 million songs on a credit card sized device, according to IEEE Spectrum.
To date, the smallest matter to have stored data was a magnetic grain with a diametre of 5 nanometers. A Holmium atom has a radius of 0.2 nanometres.
The magnetism of a single holmium atom was changed and read by flowing a current through tip of a scanning tunneling microscope.
“Disks coated with a magnetized layer of metal allow our computers to store files in the form of bits, each with the value of either 1 or 0. A certain direction of magnetization corresponds to the 0 bit, the other direction to the 1 bit,” the scientists said.
“While at the moment small areas of the disk, of around a million atoms, correspond to each digital bit of information, our research went way beyond this and utilized the smallest amount of matter usable for this purpose: one atom.”
In the study, the team worked with a scanning tunneling microscope (STM), which has a special tip that enables the user to view and move individual atoms, as well as to apply a pulse of electrical current to them.
The scientists used this electric pulse to change the direction of magnetization of individual holmium atoms.
By doing that, they could write a memory of either 1 or 0 in a single holmium atom as well as swap the two.
A quantum sensor was used to read the memory stored in the holium atom. It consists of an iron atom placed next to the holmium atom.
Using this technique, as well as another one, called tunnel magnetoresistance, the authors could observe that holmium maintains the same magnetic state stably over several hours.
Then, when they tried to use two holmium atoms instead of one, they made another surprising discovery: placing holmium atoms even one nanometer apart did not impact their ability to store information individually.
This came as a surprise, since it was expected that the magnetic field from one atom would impact its neighbor.
“To demonstrate independent reading and writing, we built an atomic-scale structure with two holmium bits, to which we write the four possible states (1-1, 0-0, 1-0 and 0-1) and which we read out both magnetoresistively and remotely by electron spin resonance,” the scientists said.
“The high magnetic stability combined with electrical reading and writing shows that single-atom magnetic memory is indeed possible.”
“There are no quantum mechanical effects between atoms of holmium. Now we want to know why,” noted lead co-author Dr. Andreas Heinrich, Director of the Center for Quantum Nanoscience at the Institute of Basic Science.
“Holmium atoms can be arranged very closely together, so the storage density using this single-atom technique could be very high,” he said.