PHYS824: Introduction to Nanophysics What is Nanophysics?

What is Nanophysics: Survey of Course Topics

What is Nanophysics: Survey of Course Topics

Branislav

K. NikolićDepartment of Physics and Astronomy, University of Delaware,

Newark, DE 19716, U.S.A.http://wiki.physics.udel.edu/phys824

PHYS824: Introduction to Nanophysics What is Nanophysics?

Definition of Nanophysical

SystemsDefinition:

Any condensed matter systems whose at least one (out of three) dimension is of the order of nanometer

can be considered as nanoscale

system.

Nanoscience

and nanotechnology are all about relating and exploiting phenomena for materials having one, two or three dimensions reduced to the nanoscale. Their evolution may be traced to three exciting happenings that took place in a short span from the early to mid-1980s with the award of Nobel prizes to each of them. These were: (i) the discovery quantum Hall effect in a two-dimensional electron gas; (ii) the invention of scanning tunnelling

microscopy (STM); and (iii) the discovery of fullerene as the new form of carbon. The latter two, within a few years, further led to the remarkable invention of the atomic force microscope (AFM) and, in the early

1990s the extraordinary discovery of carbon nanotubes

(CNT), which soon provided the launch pad for the present-day nanotechnology. The STM

and AFM

have emerged as the most powerful tools to examine, control and manipulate matter at

the atomic, molecular and macromolecular scales and these functionalities constitute the mainstay of nanotechnology.

Interestingly, this exciting possibility of nanolevel

tailoring of materials was envisioned way back in 1959 by Richard Feynman in his lecture, “There’s plenty of room at the bottom.”

Nobel Prize in Physics 2007

PHYS824: Introduction to Nanophysics What is Nanophysics?

W. Pauli: “God made solids, but surfaces were the work of Devil.”

PHYS824: Introduction to Nanophysics What is Nanophysics?

Branches of Nanoscience

PHYS824: Introduction to Nanophysics What is Nanophysics?

Why are Nanostructures Interesting for Basic Research?

Enhanced role of surface atoms with their unpaired spins and uncompensated bonds

Reduced dimensionality at the nanoscale = strogly modified Density of States, enhanced Coulomb interaction, …

Quantum confinement effects = discrete energy levelsquantum coherent effects in transport = quantum transport

Semiclassical

vs. Quantum Transport of (quasi)Electrons

PHYS824: Introduction to Nanophysics What is Nanophysics?

Limits of Top-Down Fabrication in Applied Physics and Electrical Engineering

PHYS824: Introduction to Nanophysics What is Nanophysics?

Fundamental Quantum Effects Acting Against Moore’s Law

Nonscaling

effects at nanometer MOSFETs:

quantum tunneling of carriers through the gate insulator and through the body-to-drain junction

dependence of sub-threshold behavior on temperature

discrete doping effects

power dissipated in various leakage mechanisms

PRL 98, 026802 (2007)

PHYS824: Introduction to Nanophysics What is Nanophysics?

Nanostructures: Bottom-Up Approach

Fuhrer Lab, College ParkAvouris

Lab, IBM

PHYS824: Introduction to Nanophysics What is Nanophysics?

Nanostructures Explored in PHYS824

PHYS824: Introduction to Nanophysics What is Nanophysics?

Experimental Tools of Nanoscience: STM and AFM

PHYS824: Introduction to Nanophysics What is Nanophysics?

STM Images

PRB

79, 2

0541

1 (2

009)

IBM, Almaden

Fe on Cu(111)

PHYS824: Introduction to Nanophysics What is Nanophysics?

AFM Images

Dai Lab, Science 319, 1229 (2008):Graphene Nanoribbons with

ultrasmooth edges

Kouwenhoven Lab:Double quantum dot

integrated with quantum point contacts on both sides for

spin qubit experiments

PHYS824: Introduction to Nanophysics What is Nanophysics?

Equilibrium Nanophysics: Electronic Structure and Density of States

1 2 3 4 5 6 7 8 9 100.0

0.4

0.8

1.2

1.6

-3 -2 -1 0 1 2 30.0

0.4

0.8

1.2

1.6

Loca

l DO

S at

EF=0

.01

Transverse Lattice Site

DO

S

Fermi Energy EF

3t− 2t− 1t− 0 2t1t 3tEnergy

Den

sity

of S

tate

s

holes electrons0

1

0

h)-1 0 1

-3

-2

-1

0

1

2

3

kx (1/da)

PHYS824: Introduction to Nanophysics What is Nanophysics?

Nonequilibrium

Nanophysics: Quantum Transport

Externally set energy scales:

Internal energy scales:

PHYS824: Introduction to Nanophysics What is Nanophysics?

Conductance Quantizationva

n W

ees

et a

l., P

RL 6

0, 8

48 (1

988)

Avouris

Lab, PRB 78, 161409(R) (2008)

PHYS824: Introduction to Nanophysics What is Nanophysics?

Imaging Electron Transport

PHYS824: Introduction to Nanophysics What is Nanophysics?

Quantum Hall Effect in 2DEG and Graphene

Theo

ry

PHYS824: Introduction to Nanophysics What is Nanophysics?

Weak Localization

PHYS824: Introduction to Nanophysics What is Nanophysics?

Strong (Anderson) Localization

?

PHYS824: Introduction to Nanophysics What is Nanophysics?

Electronic Interferometers and Quantum Nonlocality

PHYS824: Introduction to Nanophysics What is Nanophysics?

Quantum TunnelingEsaki D

iode (Nobel Prize 1973)

PHYS824: Introduction to Nanophysics What is Nanophysics?

Coulomb BlockadeH

. van

Hou

ten,

C. W

. J. B

eena

kker

, and

A. A

. M. S

tari

ng,

cond

-mat

/050

8454

Ensslin

Lab, APL 92, 012102 (2008)

PHYS824: Introduction to Nanophysics What is Nanophysics?

Nanophysics Applications: Spintronics

(GMR, TMR, Spin-Torque)

PHYS824: Introduction to Nanophysics What is Nanophysics?

Nanophysics Applications: Nanoelectronics

with GNRs

and CNTs