Micky HolcombWest Virginia University

Bristow, Lederman, Stanescu & Wilson

mikel.holcomb@mail.wvu.edu

Overcoming Roadblocks in Future Computing at the Center for Energy Efficient Electronics

at Marshall and WVU

http://ceee.eberly.wvu.edu/

Progress Through Size1950s

Shortening the Race = Faster

~ Every 2 years,

Twice as many transistors can fit in the

same space

With the same cost!

Doubling (Moore’s Law)

2 12 yearslater

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!

Silicon

In a transistor, a voltage on the metal can induce flow of electricity between the two other contacts

called the source (In) and drain (Out).

The flow of electricity is affected by: properties of the insulator,

the area of A&B and the insulator thickness

1) Making Them Smaller

A B

In OutVoltage (C)

Insulator

Metal

Quantum Tunneling?!?

Electrons are lazy!

If the hill isn’t too wide, they tunnel through it. Not good.

• 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.

2) Replacement Oxides

3) StrainIndustry found that it could improve

electron travel by straining—essentially squeezing—silicon.

Strain can allow quicker, more efficient

transfer of electrons.

Stress-ApparatusWilson (Marshall)

Reaching the Limits

We are reaching the limit that these strategies can continue to

improve technology.

1) Scaling2) Replacements

3) Strain

4) Different Approach: Magnetism

0 0 1

Problems with Magnetic FieldsRequire a lot of power

Heating problemsDifficult to localize – limits

size

Magnetic field

Using Magnetism

Electrical Control of Magnetism

Boundary

- Simple idea: Grow a magnetic material on

top of an electric material

Materials with strong coupling between electricity

and magnetism at room temperature are rare

- Problem: the physics at boundaries is not yet well

understood

LSMO

PZT0 2 4 6 8 10 12 14

2.4

2.6

2.8

3.0

3.2

3.4

bulk model

Mn2.5+

0 2 4 6 8 10 12 142.4

2.6

2.8

3.0

3.2

3.4

bulk model interface model

Mn2.5+

0 2 4 6 8 10 12 142.4

2.6

2.8

3.0

3.2

3.4

bulk model interface model surface model

0 2 4 6 8 10 12 142.4

2.6

2.8

3.0

3.2

3.4

bulk model interface model surface model

surface and interface model

0 2 4 6 8 10 12 142.4

2.6

2.8

3.0

3.2

3.4

bulk model interface model surface model

surface and interface model Wedge type 1 Wedge type 2

LSMO thickness (nm)

Mn v

alen

cyMn3.3+

Zhou, Holcomb, et. al. APL, submitted

One monolayer ~ Mn2.5+ (based on data)

Magnetoelectric Interfaces

Holcomb Group

SrTiO3PbZrTiO3

LaSrMnO3

La0.7Sr0.3MnO3

0 20 40 60 80 100 1203.1

3.2

3.3

3.4

LSMO thickness~2nm~3.5nm~6nm

Vale

nces

PZT thickness (nm)

We can control magnetization in LSMO

through thickness engineering.

LSMO PZTSTOLa0.7Sr0.3MnO3 PZTSrTiO3

Aberration-Corrected STEM (Collaboration with James LeBeau, NCSU)

Combined

Individual ElementsSmooth Interfaces

Thin Topological Insulators

Glinka, Bristow, Holcomb, Lederman, APL, 2013.Simplified Setup

ElectricMagnetic Magnetoelectric and two dimensional offer a

promising pathway to new devices.

As computers continue to get smaller, the physics becomes more interesting.

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.

Summary

This work is funded by