Growing and Patterning Thin Films of Pr2 –xCexCuO4-Y
Justin SousaMarco 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: Tc = 90K
• Current High Tc is 138 K, Hg0.8Tl0.2Ba2Ca2Cu3O8.33
Meissner Effect
Why Thin Films?
Advantages
• 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 μm
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 N20• Substrate is 5x5 mm of STO•Heater Temp = 850o C
Film Characterization
• AC Susceptibility
• X-Ray Diffraction
I +
I -V +
V-
PCCOPatterned
Film
Ready For Measurements
Sample Preperation
Patterning
Substrate
PCCO
Photoresist
ChromeGold
Indium Solder To Computer
Measurements at the Ithaca College Low Temperature Physics Lab
Characteristics of PCCO
• Pr2-xCexCuO4-y, x indicates the cerium concentration
• Optimal Doping is x = 0.15 with Tc = 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 = KIa 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