SpinValves by Quantum Mechanics Thomas Prevenslik QED Radiations Discovery Bay, Hong Kong NANOSMAT-Asia : Inter. Conf. Surf., Coat., Nano-Materials; Wuhan,

SpinValves by

Quantum Mechanics

Thomas PrevenslikQED Radiations

Discovery Bay, Hong Kong

NANOSMAT-Asia : Inter. Conf. Surf., Coat., Nano-Materials; Wuhan, CHINA, Mar. 13-15, 2013

1

SpinValve ferromagnetism is based on theoretical predictions by Slonczewski and Berger a decade ago.

SpinValves comprise alternating nanoscale layers of FMs separated by a NM spacer. FM stands for ferromagnetic and

NM for non-magnetic.

Spin-polarized current is produced by passing un-polarized current through a first FM layer, the polarization unchanged as

the current flows through the NM spacer.

In the second FM layer, a giant magneto-resistance (GMR) is thought to transfer the spin angular momentum as a physical spin-torque, the process tending to produce parallel spins that

significantly lower the GMR.

Introduction

2NANOSMAT-Asia : Inter. Conf. Surf., Coat., Nano-Materials; Wuhan, CHINA, Mar. 13-15, 2013

ProblemsThe significant reduction in the GMR by the alignment of

spins is not without controversy.

The relatively rigid lattice shields the spins so that any transfer of spin-torque to the second FM is unlikely.

Further, spin-torque propagates by phonons through the FM lattices, and therefore limiting spin-transfer to frequencies <

10 GHz having response times > 100 ps.

Electron spins observed to respond much faster.


3

Laser studies in femtomagnetism by Boeglin et al. show nanoscale FMs demagnetize on a sub-picosecond time scale

(< 350 fs) far faster than phonons can respond.

Spin transfer through the lattice therefore cannot be the mechanism for demagnetization

Bigot et al. showed about 10 ps for the lattice to thermalize prompting Bovensiepen to suggest SpinValves de-magnetize

by light noting* the dynamics are only observed while the laser field interacts with the FM

* Similarity with the EM confinement of a TIR quasi-bound state, trapped in a

potential well , but leaking to the outside world by tunneling.

Alternatives


4

Provided the RI of the FM is greater than that of the adjacent NM spacers, non-thermal EM radiation at EUV levels is created by the QED induced frequency up-conversion of Joule heat to the TIR confinement frequency of the FM.

RI = refractive index. EM = electromagnetic

QED = quantum electrodynamics

EUV = extreme UV, TIR total internal reflection

Excitons (holon and electron pairs) are readily created by the QED induced photoelectric effect.

Holons (positive holes) act as charge carriers that significantly reduce the GMR of the FM by a dramatic

increase in photoconductivity.

QED Induced Radiation


5


Theory

Heat Capacity of the Atom

Conservation of Energy

TIR Confinement

6

Heat Capacity of the Atom

1 10 100 10000.00001

0.0001

0.001

0.01

0.1

Thermal Wavelength - l - microns

Pla

nck

Ene

rgy

- E

- e

V

1

kT

hcexp

hc

E

7

Nanostructures

kT 0.0258 eV

Classical Physics (kT > 0)

QM(kT = 0)


In nanostructures, QM requires atoms to have zero heat capacity


Conservation of Energy

Lack of heat capacity by QM precludes Joule heat conservation in nanoelectroncs by an increase in

temperature, but how does conservation proceed?

ProposalAbsorbed EM energy is conserved by creating QED photons inside the nanostructure - by frequency up - conversion to the

TIR resonance of the nanostructure.

8

Since the RI of nanoelectroncs is greater than that of the surroundings, the QED photons are confined by TIR

corresponding to a quasi-bound state

Nanostructures ( films, wires, etc) have high surface to volume ratio, but why important?

By QM, the EM energy absorbed in the surface of nanostructures provides TIR confinement of the QED photons.

QED photons are spontaneously created by Joule heat dissipated in nanoelectronics. Simply,

f = c/ = 2nd E = hf

TIR Confinement


For a spherical NP having diameter D, = 2D


Electrical Response

QED Photons and Excitons

Exciton Response

Mobility

Resistance and Current

10

QED Photons and Excitons


d Ndt

= P

E

d N ex

dt=Y

d N P

dt=YP

E

QED Photon Rate

P = Joule heatE = QED Photon energy = Absorbed Fraction

Exciton Rate

Y = Yield of Excitons / QED Photon

11

Exciton Response


Where, QE and QH are number electrons and holons, V is the voltage

E and H are electron and holon mobility

d QE

dt=ηP

E−QE

μE V

L2

ElectronsdQH

dt=ηP

E−QH

μH V

L2

Holons

12

QH= L2

H V o { Y PE [1−exp (− H V o

L2 t)]+ H V o

L2 QH 0 exp (− H V o

L2 t )} For SpinValves, Ovshinsky effect , and 1/f Noise, V = Vo,

For memristors, V = Vo sin t.

∫0

𝑡

exp(− μH V o

d2 cos t) dtQH exp(− μH V o

d2 cos t )= YPE

Chen et al. expressed mobility at ambient temperature by,

where, o is the mobility at zero field F

For Alq3, = 9.22x10-3 (cm/V)1/2 .

Typically, Independent of field : o = 3.04x10-7 cm2/V-s.

Mobility


Resistance and Current


R= d2 A

=d

2 A1

e ( EQE+μH Q¿¿ H) / Add2

4 e μH QH

¿

I=V oR

∨V O sin ωt

R

=1

=e (QE E+QH H )

14

= Conductivity = Resistivity


Applications

SpinValves

Briefly

Memristors

Ovshinsky Effect 1/f Noise

15

The QED induced switching is simulated for Alq3 film thicknesses of 10, 20, 50, and 100 nm. All films were assumed to have an initial GMR of Ro = 1x106 ohms. A voltage Vo = 1 V

was applied for 10 ns followed by Vo = -1 V for 10 ns

The QED induced reduction in GMR is significant

The 10 nm film resistance ratio R/Ro is reduced to ~ 0.000624 or (R ~ 624 ohms) in < 1 ns.

In contrast, magnetic induced GMR reductions for 125 nm Alq3 film at 100 K shows a GMR reduction of about 22%

corresponding to R/Ro = 0.78

SpinValves - Simulation


SpinValves - Resistance


GMR resistance change - Write and ReadFor +1 V write and -1 V erase cycle

17

0 2 4 6 8 10 12 14 16 18 200.0001

0.001

0.01

0.1

1

Time - t - ns

Re

sist

an

ce R

atio

- R

/RO

100 nm

50 nm

20 nm10 nm

Write Erase

10 nm

Spin only Vo = + 1 V Vo = -1 V

SpinValves - Charges


0 2 4 6 8 10 12 14 16 18 201E+01

1E+02

1E+03

1E+04

1E+05

1E+06

1E+07

1E+08

1E+09N

um

be

r o

f H

olo

ns

- Q

H

Time - t - ns

10 nm

20 nm

50 nm

100 nm

Vo = + 1 V Vo = -1 V

Holon charges - Write and ReadFor +1 V write and -1 V erase cycle

18

The 10 nm film resistance change predicted by the QED induced photoelectric effect in GST films suggests superconductivity already exists or at least may be

approached at ambient temperature.

Superconductive nanowires are proposed* to sense single photons from an external source.

C. Soci, et al., “Nanowire Photodetectors,” J. Nanoscience and Nanotechnology, 10, 1-20, 2010

However, nanowires may be a natural QED induced superconductive interconnect in nanoelectronics.

SpinValves - Conclusions


Memristors


-1.5 -1 -0.5 0 0.5 1 1.5

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

Voltage - V - Volts

Cur

rent

-

I -

Am

ps

d = 50 nm , GST mobility H = 2x10-6 cm2/V-s

20

QM creates Space Charge to change Memristor resistance ( HP claims Oxygen vacancies )

Ovshinsky Effect


0.1 1 10 100 1000100

1000

10000

100000

1000000

10000000

Time - t - ns

Res

ista

nce

- R

- O

hms

d = 1000 nm

d = 100 nm

d = 10 nm

Alq3 Mobility = 2x10-5 cm2/V-s, Vo = 1 V, Ro = 1 M

21

PCRAM resistance changes from QED Induced charge ( Melting is ambiguous)

1/f Noise in Nanowires


G (2𝜋 𝑓 )= ∫− τ /2

τ /2

1e− jωt dt=sin ( πτ )

πf=1/ 𝑓

Step in QED Induced Charge Step in Current Step in Power

Fourier Transform of Step in Power gives 1/f Noise

/2- /2

X(t)

t

22

QM creates holons as current enters nanowire( Hooge relation based on free electrons )

By QM, submicron nanoelectronic circuit elements:

SpinValves

Memristors

Ovshinsky Devices

Nanowire Interconnects

do not increase in temperature because Joule heat is conserved by the creation of charge.

However, the QED induced charge may significantly increase the 1/f noise.

Conclusions


Questions & Papers

Email: [email protected]

http://www.nanoqed.org


http://www.nanoqed.org/

Documents

SpinValves by Quantum Mechanics Thomas Prevenslik QED Radiations Discovery Bay, Hong Kong NANOSMAT-Asia : Inter. Conf. Surf., Coat., Nano-Materials; Wuhan,