Olle Heinonen
Materials Scientist Olle Heinonen (MSD) will discuss his Laboratory-Directed Research and Development (LDRD) sponsored work at the LDRD Seminar Series presentation Tuesday, Feb. 28, 2017.
“Resistive Random Access Memories — A Look Under the Hood Using Quantum Simulations” will begin at 12:30 p.m. in the Bldg. 203 Auditorium. All are welcome to attend.
Abstract
Computing power and data storage capabilities have increased exponentially for the past several decades. This is Moore’s law, which expresses the doubling of the number of transistors per area unit in integrated circuits. What has enabled Moore’s law is scaling: a relentless reduction in device size. But the end of Moore’s law is now in sight with critical dimensions in devices approaching 5 nm. At this length, processing becomes extremely difficult and expensive, and device functions do not scale any more as the physics controlling the devices changes. At the same time, the power density due to dissipation is becoming a big problem not only for device reliability but also for projected global energy consumption in information technology devices. There is therefore a great need for technologies that can replace Si-MOSFET and that can also reduce power consumption.
One such potential technology for nonvolatile memories is resistive random access memories (RRAMs). Nonvolatile memories retain their information when power is turned off, with obvious energy savings compared with volatile ones. RRAMs are based on a phenomenon of resistive switching, which is observed in almost any transition metal oxide (as well as other materials) sandwiched between two metals. Such structures can switch reversibly between a high-resistance and a low-resistance state. RRAMs are currently being researched intensively in academia, national laboratories and industry, but much of the fundamental physics is still not known well.
In an LDRD-funded project, we used various atomic-scale modeling approaches to investigate some fundamental properties of the materials in RRAMs as well as some specific RRAM structures that are currently leading candidates for devices. In particular, we looked at how minute changes at the atomic level can dramatically alter the device. For example, the movement of a single oxygen atom a distance of about 1 nm can increase the resistance about three orders of magnitude. Our work also clarifies the advantage of adding a few nanometers of a metal such as tantalum next to an electrode. I will in this talk present some of the basics of RRAMs and also present some of the more surprising highlights of our research.
Biography
Olle Heinonen joined Argonne in 2010, and works in computational and theoretical materials science in areas from quantum effects of electronic interactions to the behavior of magnetism in nanoscale magnetic structure and microstructural evolution in super-alloys in turbine blades. A common theme in his research is how competing interactions in structured materials systems can lead to complex behavior that can be harnessed.
Heinonen is a Fellow of the Computation Institute at the University of Chicago, and a Fellow of the Northwestern-Argonne Institute of Science and Engineering. He earned his Ph.D. in Physics at Case Western Reserve University and was elected Fellow of the American Physical Society in 2014.
Prior to joining Argonne, Olle was on the faculty at the Department of Physics, University of Central Florida for nine years. After that he worked at Seagate Technology at the recording heads operations in Minneapolis. At Seagate he worked for twelve years on research and development of magnetic recording heads, including giant magnetoresistance and tunneling magnetoresistance, and also on non-volatile RRAMs and spin-torque magnetic random access memories.