Heat has become one of the most critical issues in computer and semiconductor design: The ever increasing number of transistors in computer chips requires more efficient cooling approaches for the hot spots which are generated as a result of the operation of the transistors. Researchers at RMIT University in Australia have demonstrated a microfluidic technique of using thermally conductive and magnetic chromium oxide nanoparticles that can form low-dimensional fins in the vicinity of hot spots.
Carbon nanotubes are hollow, cylindrical molecules that can be manipulated to give them useful properties. The nanoparticles were discovered accidentally on the rough surfaces of a reactor designed to grow carbon nanotubes.
Described as sea urchins because of their characteristic spiny appearance, the particles consist of nanotubes filled with iron, with equal lengths pointing outwards in all directions from a central particle.
The presence of iron and the unusual nanoparticle shape could have potential for a number of applications, such as batteries that can be charged from waste heat, mixing with polymers to make permanent magnets, or as particles for cancer therapies that use heat to kill cancerous cells.
The researchers found that the rough surfaces of the reactor were covered in a thick powder of the new nanoparticles and that intentional roughening of the surfaces produced large quantities of the sea urchin nanoparticles.
“The surprising conclusion is that the sea urchin nanoparticles grow in vapour by a mechanism that’s similar to snowflake formation. Just as moist air flowing over a mountain range produces turbulence which results in a snowfall, the rough surface disrupts a flow to produce a symmetrical and ordered nanoparticle out of chaotic conditions,” said Dr Mark Baxendale from Queen Mary’s School of Physics and Astronomy.
On analysis, the researchers found that a small fraction of the iron inside the carbon nanotubes was a particular type usually only found in high temperature and pressure conditions.
Dr Baxendale added: “We were surprised to see this rare kind of iron inside the nanotubes. While we don’t know much about its behaviour, we can see that the presence of this small fraction of iron greatly influences the magnetic properties of the nanoparticle.”
Memory breakthrough could bring faster computing, smaller memory devices and lower power consumption
(Nanowerk News) Memory devices like disk drives, flash drives and RAM play an important role in our lives. They are an essential component of our computers, phones, electronic appliances and cars. Yet current memory devices have significant drawbacks: dynamic RAM memory has to be refreshed periodically, static RAM data is lost when the power is off, flash memory lacks speed, and all existing memory technologies are challenged when it comes to miniaturization.
Increasingly, memory devices are a bottleneck limiting performance. In order to achieve a substantial improvement in computation speed, scientists are racing to develop smaller and denser memory devices that operate with high speed and low power consumption.
Published in Nature Communications, the research paper, A chiral-based magnetic memory device without a permanent magnet, was written by Prof. Yossi Paltiel, Oren Ben Dor and Shira Yochelis at the Department of Applied Physics, Harvey M. Krueger Family Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem; and Shinto P. Mathew and Ron Naaman at the Department of Chemical Physics, Weizmann Institute of Science.
The research deals with the flow properties of electron charge carriers in memory devices. According to quantum mechanics, in addition to their electrical charge, electrons also have a degree of internal freedom called spin, which gives them their magnetic properties. The new technique, called magnetless spin memory (MSM), drives a current through chiral material (a kind of abundantly available organic molecule) and selectively transfers electrons to magnetize nano magnetic layers or nano particles. With this technique, the researchers showed it is possible to create a magnetic-based memory device that does not require a permanent magnet, and which could allow for the miniaturization of memory bits down to a single nanoparticle.
The potential benefits of magnetless spin memory are many. The technology has the potential to overcome the limitations of other magnetic-based memory technologies, and could make it possible to create inexpensive, high-density universal memory-on-chip devices that require much less power than existing technologies. Compatible with integrated circuit manufacturing techniques, it could allow for inexpensive, high density universal memory-on-chip production.
According to the Hebrew University’s Prof. Paltiel, “Now that proof-of-concept devices have been designed and tested, magnetless spin memory has the potential to become the basis of a whole new generation of faster, smaller and less expensive memory technologies.”
The technology transfer companies of the Hebrew University (Yissum) and the Weizmann Institute of Science (Yeda) are working to promote the realization of this technology, by licensing its use and raising funds for further development and commercialization. With many possible applications, it has already attracted the attention of start-up funds.
The Hebrew University’s Center of Nanoscience and Nanotechnology helped with device fabrication and advice. Prof. Paltiel acknowledges the Yessumit internal grant from the Hebrew University, and Ron Naaman and Shinto P. Mathew acknowledge the support of the Minerva Foundation.