Green Your Machine: The
Physics of More Efficient
Computers and Cell Phones
See the notes in the PPT file for ~script.
Condensed Matter Physicist
West Virginia University
Progress Through Size
Shortening the Race = Faster
Doubling (Moore’s Law)
~ Every 2 years,
With the same cost!
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!
What is Electricity?
In some materials (metals),
these electrons move freely
under an applied voltage.
1) Making Them Smaller
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
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.
Industry found that it could improve
electron travel by straining (essentially
Strain can allow quicker,
more efficient transfer of
Reaching the Limits
We are reaching the limit that
these strategies can continue to
4) Different Approach: Magnetism
Problems with Magnetic Fields
Require a lot of power
Difficult to localize – limits size
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
- Problem: the physics at
boundaries is not yet well
Pulsed Laser Deposition (PLD)
fabrication of such
Femtosecond pulses, one million
times smaller than nanoseconds!
Power of a laser pen:
Power of our lab’s laser:
Paper will burn at 95 mW
Cooling Down the Physics
Antarctica reaches temperatures of
Cryostat: where the material is
Capable of reaching temperatures of
This is just above ABSOLUTE ZERO,
the coldest possible temperature.
Other cool features:
Low vibration stage
Experiments At National Labs:
X-ray Absorption Spectroscopy
Photoemission Electron Microscopy (PEEM)
Electric Control of Magnetism
First E switch
Arrows indicant direction of
magnetism (0 or 1)
Second E switch
Basic physics research has allowed significant progress in
computing and other modern day technologies.
As computers continue to get smaller, the physics
becomes more interesting.
Magnetoelectric materials offer a pathway to new devices.
Magnetic and ferroelectric materials can be imaged and
studied at WVU and national laboratories.
Magnetic domains can be changed by an electric field.
This work is funded by
Our Science Superheroes
A few of my collaborators:
Left to Right: Srinivas Polisetty (post-doc),
Disheng Chen (grad), Jinling Zhou (grad), Evan
Wolfe (undergrad), Micky Holcomb (advisor) and
National Chiao Tung University (Taiwan)
Charles Frye (undergrad)