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2016.01 Congratulations to Dr. Gifford's new position at IBM!
Dr. Jessica Gifford join ASU in 2011!
She defended on 11/09/2015, and her thesis is,
"Andreev Reflection Spectroscopy:
Theory and Experiment"
Jess left ASU on 01/14/16 for her new position @IBM!
Jess, best, stop by whenever you're nearby.
2015.05 Superconductivity in Epitaxial Bi/Ni Bilayers
Chin. Phys. Lett. 32, 067402 (2105)
Not superconducting
Not superconducting
+
Superconducting
with Tc about 4K!
Intriguing thickness dependence on both Ni and Bi:
- Increasing Ni kills superconductivity
-Increasing Bi recovers superconductivity
Read the paper ...
2015.05 Congratulations to Salar!
Undergraduate student Salar Simaie won the 2015 Tsong Prize for
Undergraduate Research in the Department of Physics at ASU for
his work on measurement of Anomalous Nernst Effect in Py/Pt and
Co/Pt films.
The annual Tsong prize was endowed by Prof. Ignatius Tsong to
encourage undergraduate research in Physics at ASU.
In addition, Salar is also a recipient of
- Outstanding Honor Thesis in SEMTE at ASU, 2015
- Barret creative project funds
- APS travel grant
Salar will go to Purdue for his graduate studies, congratulations.
2015.04.20
Control of thermal gradient using thermoelectric coolers for study of thermal effects
J. Zhang, J. A. Gifford, G. J. Zhao, D. R. Kim, C. N. Snider, N. Vargas, and T. Y. Chen
J. of Appl. Phys. 117, 17C508 (2015).
Thermal current is not easy to control,
very different from electric current.
Using TECs, in this paper we show that,
- Seebeck and Nernst effect are often mixed due to unexpect theraml gradient.
- Seebeck and Nernst effect can be sepaarted using their properties.
- Anomalous Nernst effect in Pt/Ni and Pt/Co are measured.
Read the paper ...
2013.04.09
Effect of three dimensional interface in determination of spin polarization using Andreev reflection spectroscopy
J. A. Gifford,a) C. N. Snider, J. Martinez, and T. Y. Chen
Point contacts are not perfectly 1D, what are the effects of a 3D point contact?, In this paper, we show that,
- Point angle affects Andreev spectrscopy
- Can be attributed to Z factor
- Spin polarization can still be determined
- Superconducting gap can still be determined
- No effect for perfect interface with Z=0
Read the paper ...
Unified Formalism of Andreev Reflection at a Ferromagnet/Superconductor Interface
T.Y. Chen, Z. Tesanovic, and C. L. Chien
Phys. Rev. Lett. 109, 146602 (2012)
In this paper, we show that,
- Unified formlism for Andreev reflection spectroscopy
- Same results as the linear combination model
- Inclusion of effect from inelastic scattering
- Polarized current becomes evanescent
Read the paper ...
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