# Matthew C. Sullivan

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15 Νοε 2013 (πριν από 4 χρόνια και 6 μήνες)

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Growing and Patterning Thin Films of
Pr
2

x
Ce
x
CuO
4
-
Y

Justin Sousa

Marco Salvaggio

Matthew C. Sullivan

Department of Physics,

Ithaca College, Ithaca NY

Superconductivity: What is it?

Superconductivity is the ability of certain materials to
conduct electric currents with zero resistance.

Discovered in 1911 by Heike Kamerlingh Onnes, Mercury: Tc = 4.2K

1987: “High Temperature” Superconductivity,
YBCO
: T
c

= 90K

Current High T
c

is 138 K,
Hg
0.8
Tl
0.2
Ba
2
Ca
2
Cu
3
O
8.33

Meissner Effect

Why Thin Films?

Easy to grow within range of 1000 Å ≤ T ≤ 5000 Å

Easy to get uniform currents

Much harder to make measurements on crystals

Substrate: 0.5 mm = 500
μ
m

PCCO
≈ 3000 Å

Film Growth

Check out our video at

www.ithaca.edu/physics

Plume

Heater

Substrate

PCCO

Vacuum Chamber

Pulsed Laser Deposition

KrF Laser:
λ
= 248 nm

Chamber filled with N
2
0

Substrate is 5x5 mm of STO

Heater Temp = 850
o

C

Film Characterization

AC Susceptibility

X
-
Ray Diffraction

I +

I
-

V +

V
-

PCCO

Patterned
Film

Measurements

Sample Preperation

Patterning

Substrate

PCCO

Photoresist

Chrome

Gold

Indium Solder

To
Computer

Measurements at the Ithaca College
Low Temperature Physics Lab

Characteristics of PCCO

Pr
2
-
x
Ce
x
CuO
4
-
y
,
x

indicates the cerium concentration

Optimal Doping is
x

= 0.15 with T
c

= 20 K

We have studied the range of 0.13

x

0.19

IV Data for Optimally Doped PCCO

Critical Isotherm

T = 21.60 K

V = KI
a

becomes:

log(V) = a log(I)

where a is the slope.

Ohmic behavior implies

a = 1, K = R

or V = IR

Future Work

Continue to look for the critical exponent in films of different dopings

Measure critical current and critical field in PCCO and YBCO

Thanks to

Dr. Matthew C Sullivan

The Ithaca College Dana Internship Committee

The Center for Superconductivity Research at The University of Maryland