Micky Holcomb West Virginia University Bristow, Lederman, Stanescu & Wilson

Overcoming Roadblocks in Future Computing at the Center for Energy Efficient Electronics at Marshall and WVU Micky Holcomb West Virginia University Bristow, Lederman, Stanescu & Wilson http://ceee.eberly.wvu.edu/ mikel.holcomb@mail.wvu.edu

Progress Through Size 1950s

Shortening the Race = Faster

Doubling (Moore’s Law) ~ Every 2 years, Twice as many transistors can fit in the same space With the same cost! 12 years later 2 Today, >200 million transistors can fit on the head of a pin! By 2050 - if trends continue - a device the size of a micro-SD card will have storage of ~ 3x the brain capacity of the entire human race!

1) Making Them Smaller In a transistor, a voltage on the metalcan induce flow of electricity between the two other contacts called the source (In) and drain (Out). Voltage (C) In Out Metal Insulator B A Silicon The flow of electricity is affected by: properties of the insulator, the areaof A&B and the insulator thickness

Quantum Tunneling?!? Electrons are lazy! If the hill isn’t too wide, they tunnel through it. Not good.

2) Replacement Oxides • Insulating properties (resists electron flow) • “Plays nice” with current Si technology (temperature and quality) • Many materials have been tried but none are as cheap and easy to manipulate as existing SiO2.

3) Strain Industry found that it could improve electron travel by straining—essentially squeezing—silicon. Strain can allow quicker, more efficient transfer of electrons. Stress-Apparatus Wilson (Marshall)

Reaching the Limits 1) Scaling 2) Replacements 3) Strain We are reaching the limit that these strategies can continue to improve technology.

 4) Different Approach: Magnetism

Using Magnetism 0 0 1 Problems with Magnetic Fields Require a lot of power Heating problems Difficult to localize – limits size Magnetic field

 Electrical Control of Magnetism Materials with strong coupling between electricity and magnetism at room temperature are rare - Simple idea: Grow a magnetic material on top of an electric material Boundary - Problem: the physics at boundaries is not yet well understood

Holcomb Group Magnetoelectric Interfaces LaSrMnO3 PbZrTiO3 SrTiO3 Zhou, Holcomb, et. al. APL, submitted Mnvalency Mn2.5+ La0.7Sr0.3MnO3 LSMO Mn3.3+ Combined Individual Elements Smooth Interfaces We can control magnetization in LSMO through thickness engineering. LSMO thickness (nm) Mn2.5+ PZT LSMO La0.7Sr0.3MnO3 PZT SrTiO3 STO PZT One monolayer ~ Mn2.5+ (based on data) Aberration-Corrected STEM (Collaboration with James LeBeau, NCSU)

Thin Topological Insulators Simplified Setup Glinka, Bristow, Holcomb, Lederman, APL, 2013.

Summary Magnetic Electric As computers continue to get smaller, the physics becomes more interesting. Magnetoelectric and two dimensional offer a promising pathway to new devices. These materials can be imaged and studied at WVU, Marshall and national laboratories. Exciting information about the structure and interface has provided a deeper understanding which we hope to exploit for improved technology. This work is funded by

Micky Holcomb West Virginia University Bristow, Lederman, Stanescu & Wilson