Wolfgang Porod Center for Nano Science and Technology University of Notre Dame ndnano 1 st Berkeley Symposium on Energy Efficient Electronics

Wolfgang PorodCenter for Nano Science and TechnologyUniversity of Notre Damehttp://www.nd.edu/~ndnano

1st Berkeley Symposium on Energy Efficient Electronics ● 11 June 2009

Nanomagnetic Logic

Supported by NSF, ONR, and SRC-NRI

Center for Nano Science and Technology

SRC-NRI Funded Centers

2

ColumbiaHarvardPurdueUVAYaleUC Santa BarbaraStanfordU. MassU. ArkansasU. OklahomaNotre DameU. Nebraska/LincolnU. MarylandCornellUT AustinCaltech

UC Los AngelesUC BerkeleyUC IrvineUC Santa BarbaraStanfordU DenverPortland StateU Iowa

Notre Dame PurdueIllinois-UC Penn StateMichigan UT-Dallas

UT-Austin Rice Texas A&MUT-Dallas ASU Notre DameU. Maryland NCSU Illinois UC

SUNY-Albany GIT HarvardPurdue RPI ColumbiaCaltech MIT NCSUYale UVA


“Magnetic components are rather attractive to the computer designer for several reasons:

•They posses an inherent high reliability•They require in most applications no power

other than the power to switch their state•They are potentially able to perform all required operations, i.e., logic, storage and

amplification “

H. W. Gschwind, Design of Digital Computers © 1967 by Springer-Verlag.

The Elliott 803 computerThe machine was compact (requiring around 400 square feet of floor-space) had undemanding power requirements (3.5 kilowatts plus at least 10 kilowatts of air conditioning) and, most importantly, offered hardware floating point arithmetic as an option, so the Elliott could be used as a low cost scientific machine. Several aspects of the machine's technology are rather unusual.Such as, the basic switching technology is built from germanium transistors and a large number of ferrite core logic elements used, not as memory, but as a logic gate. The most common configuration is illustrated below.


Quantum-Dot Cellular Automata

Represent binary information by charge configuration

A cell with 4 dots

2 extra electrons

Neighboring cells tend to align due to directCoulombic coupling

A Quantum-Dot Cell

An Array of Cells


1 1-1 -1

A

B

C

Out

-11 1-1

Binary wire

InverterMajority gate

MABC

Programmable 2-input AND or OR gate.

QCA Devices


From metal-dot to molecular QCA

“dot” = metal island70 mK

Mixed valence compounds

“dot” = redox center

Metal-dot QCA established proof-of-principle.but …low T, fabrication variations

Molecular QCA: room temp, synthetic consistency

room temperature+

Metal tunnel junctions


First room temperature magnetic “quantum-dot cellular automata”

R.P. Cowburn and M.E. Welland SCIENCE, VOLUME 287, 1466 (2000)

R.P. Cowburn JOURN MAGNETISM MAGNETIC MAT, VOLUME 242, 505 (2002)

Evolution of a soliton propagating along a chain of coupled nanomagnets under the action of a 30Oe field applied:

The circular dots, each of diameter 110 nm, placed on a pitch of 135 nm. The dots were 10 nm thick and were made from the common magnetic alloy supermalloy (Ni80Fe14Mo5X1, where X is other metals) by e-beam lithography and lift-off.


Mag

neto

stat

ic e

nerg

y

0

150

300

kT

nm20

nm100

nm50 15nm

M

90 270

Coupled NanomagnetsCoupled Nanomagnets

Strong Coupling Stable PatternsStrong Coupling Stable Patterns


Gary H. Bernstein, Alexandra Imre, Zhou Ling, George Csaba

Observe Magnetic Field Coupling

Atomic-Force and Magnetic-Force Microscopy (AFM and MFM)


Approx. 36 µm


Biomineralization in Magnetotactic BacteriaBob Kopp, 2001

Joseph L Kirschvink et al.

Magnetite Biomineralization


Experimental demonstration of antiferromagnetic ordering

16 dots long chain contains 30 nm thick permalloy nanomagnets made by e-beam lithography and lift-off

SEM

AFM

MFM


Experimental demonstration of ferromagnetic ordering with input

16 dots long chain contains 30 nm thick permalloy nanomagnets made by EBL and lift-off

AFM MFM

H


Majority gate geometry

M.C.B. Parish and M. Forshaw, APPL. PHYS. LETT. 83, 2046 (2003)

A different version off the majority “cross” geometry was proposed by


Demonstration of majority gate operation

A. Imre et al, SCIENCE, VOL. 311, 205 (2006)


Proposed Drive Circuitry

1 wire controls 1000s of magnets


Aggregate EnergySources of Energy

1. Hysteresis loss in magnets

2. Cu wire resistance, parasitics3. Clock generation circuitry (not shown)

Nanomagnet Studies

G. Csaba, J. of Comp. Elec., vol. 4(1/2), pp. 105–11, 2005.

1010 magnets switch 108 times/s, ~ 0.1 W

Wire Drivers

We add 25% energy

overhead per wire to estimate

Clock Wire Studies

•Niemier, et. al., “Clocking structures and power analysis for nanomagnet-based logic devices,” ISLPED, pp. 26–31, 2007.

• Hclock is a function of current density•Greater J > Hclock > I > P (as a function of I2)

• Should be most significant energy consumer in a computation


Energy Delay Product (EDP) Estimates

EDP Estimate for 32-bit CMOS Ripple Carry Adder

Magnets with feature sizes can outperform CMOS

equivalents in EDP

Scaling should further reduce

MQCA EDP

Can also investigate materials to

increase relative permeability

Pierambaram, “Enhanced Permeability Device Structures and Methods”, Dec.

17, 2007, US Patent Application US 2007/0284683 A1


Thanks to …• Magnetic QCA

– Edit Varga and Tanvir Alam (NDnano) … Fabrication and MFM

– Alexandra Imre (ANL) … Fabrication and MFM

– George Csaba and Paolo Lugli (TUM) … Theory and Modeling

– Gary Bernstein and Alexei Orlov (NDnano) … Fabrication and Testing

– Michael Niemier and Sharon Hu (NDnano) … Architectures

• Sponsors– Office of Naval Research

– National Science Foundation

– Semiconductor Research Corporation

Documents

Wolfgang Porod Center for Nano Science and Technology University of Notre Dame ndnano 1 st Berkeley Symposium on Energy Efficient Electronics