David Parker
Dept. of Physics
Welcome to my webpage.
I will soon have a recent picture to put here.
I work on various aspects of superconductivity, including BCS theories of unconventional superconductivity
for materials such as PrOs4Sb12 and CeCoIn5. Here are links to some of my papers:
Impurity Bound States in Pseudogap Phase of High-Tc Cuprates
Gap Symmetry of Superconductivity in UPd2Al3
Triplet Superconductivity in Skutterudite PrOs4Sb12
High-Tc Cuprate Superconductivity in a Nutshell
BCS Theory of Nodal Superconductors (review)
Anisotropic Superconductivity in PrOs4Sb12 (preprint)
Upper critical field Hc2 in PrOS4Sb12 (preprint)
Gossamer Superconductivity, New Paradigm? (preprint)
Here’s my current (10/05) CV.
Curriculum Vitae
DAVID PARKER
Department of Physics and Astronomy
Tel:(213)740-1104 FAX: (213)740-6653
URL:http://physics.usc.edu/~davidspa
Email: davidspa@usc.edu
Education
·
Ph.D. in Physics,
May 2006,
3.94
GPA in Physics courses.
Thesis topic: Theory of Unconventional Superconductivity
Advisors: Prof. Kazumi Maki and Prof. Stephan Haas
·
B.A. in Physics, cum laude,
Employment
·
Visitor,
Max-Planck Institute for the Physics of Complex Systems,
·
Research
Assistant, Physics Department,
·
Teaching Assistant,
Physics Department,
·
Air Quality
Engineer II,
·
Staff Air
Pollution Specialist,
Teaching Experience
·
“Physics for the
Life Sciences”, laboratory section, USC (fall 2005)
·
“Optics and
Modern Physics”, laboratory section, USC (spring 2004, summer 2001, summer
2002)
·
“Electricity and
Magnetism”, laboratory section, USC (summer 2003)
·
“Conceptual
Physics”, laboratory section, USC (fall 2001 – fall 2004)
·
‘The Universe”,
astronomy laboratory section, USC (fall 2001 – fall 2004)
Publications
1.
Impurity Bound States in the Pseudogap Phase
of High-Tc Cuprates. D. Parker, K. Maki, S. Haas, Acta Physica
Polonica B 34, 583 (2003).
2.
Gap Symmetry of Superconductivity in UPd2Al3. H. Won, D. Parker, K. Maki,
T.
Watanabe, K. Izawa, Y. Matsuda, Phys.
Rev. B 70, 140509 (2004).
3.
Triplet Superconductivity in the
Skutterudite PrOs4Sb12. K. Maki,
4.
Aspects of Nodal Superconductivity.
H. Won, D. Parker,
Curr. Appl. Phys. 4, 523 (2004).
5.
High-Tc Cuprate
Superconductivity in a Nutshell. H. Won, S. Haas, D. Parker, K. Maki, Physica Status Solidi B 242, 363 (2005).
6.
Perspectives on Nodal Superconductors. K.
Maki, S. Haas, D. Parker, H. Won, Chinese Journal of Physics 43, 532 (2005).
7.
BCS Theory of Nodal Superconductors (review).
H. Won, S. Haas, D. Parker, S. Telang, A. Vànyolos and K. Maki, Lectures on
the Physics of Highly Correlated
Electron Systems IX, AIP Conference Proceedings Vol. 789,
2005; also available as cond-mat/0501463.
8.
BCS Theory of p+h-wave Superconductivity.
D. Parker,
9.
Anisotropic Superconductivity in PrOs4Sb12. D. Parker, K. Maki,
10. Upper Critical Field Hc2 in
Triplet Superconductor PrOs4Sb12. D. Parker, K. Maki,
H. Won (2005), in preparation.
11.
Impurity Effects in PrOs4Sb12.
D. Parker, S. Haas and K. Maki (2005), in preparation.
12. Anisotropy
in the Upper Critical Field and the Square Vortex Lattice in
High-Tc Cuprates La2-xSrxCuO4.
D. Parker, K. Maki and H. Won (2005), in
preparation.
13. Possible
Fulde-Ferrell-Larkin-Ovchinnikov Superconducting State in CeCoIn5:
New Evidence from Pressure Studies.
C.F. Miclea, M. Nicklas, D. Parker, K. Maki, J.L. Sarrao, G. Sparn, J.D.
Thompson and F. Steglich (2005), in preparation.
14.
Gossamer Superconductivity, New Paradigm?
H. Won, S. Haas, K. Maki, D. Parker, B. Dora and A. Virosztek (2005), to be
published in Physica Status Solidi C.
Available at cond-mat/0508234.
15.
Scaling Relations of the Thermal
Conductivity in the Triplet Superconductor PrOs4Sb12. K. Maki, H. Won and D. Parker, to be
published in Physica C.
16.
Scaling Relations in the
D.
Parker and H. Won (2005), to be published in Journal de Physique IV;
cond-mat/0508249.
17. Topological Defects in Triplet Superconductors UPt3, Sr2RuO4, etc. K. Maki, S. Haas, D. Parker and H. Won (2005), to be published by World Scientific as proceedings of International Conference on Topological Science (TOP 2005) held at Sapporo, Japan on March 7-10, 2005; cond-mat/0504635.
Seminars and Presentations
● BCS Theory of
p+h-wave Superconductivity
Strongly Correlated Electron Systems 2005 Conference,
(poster presentation,
● Unconventional
Superconductivity in PrOs4Sb12
APS
March meeting,
● Unconventional Superconductivity in PrOs4Sb12
● Weak-Coupling
BCS Theory of Superconductivity in PrOs4Sb12
Ninth Training Course in Physics of Correlated
Electron Systems and
High-Tc Superconductors,
● Anisotropic Superconductivity in A Phase
of PrOs4Sb12
Caltech,
References
Prof.
Stephan Haas Prof.
Kazumi Maki
Dept.
of Physics and Astronomy Dept. of Physics and Astronomy
Phone
(213)740-4528 Phone
(213)740-8405
FAX (213)740-6653 FAX (213)740-6653
E-mail:
shaas@usc.edu E-mail:
kmaki@usc.edu
Prof.
Gene Bickers Prof.
Richard Thompson
Dept.
of Physics and Astronomy Dept. of Physics and Astronomy
Phone
(213)740-1114 Phone
(213)740-1131
FAX (213)740-8094 FAX (213)740-6653
E-mail: bickers@usc.edu E-mail:
rsthom@usc.edu
Statement of Research Interests
My
main research interest at present is in applying the BCS theory of superconductivity
to unconventional superconductors such as PrOs4Sb12, with
particular emphasis on the novel thermodynamic properties associated with
unconventional, or non s-wave, pairing.
Recent research I have performed on PrOs4Sb12
includes analytic limiting-case and numerical calculations of the order
parameter, density of states, specific heat, critical field and superfluid
density. These calculations have been
completed for the clean-limit case and for the impurity scattering case. This research is inspired by recent
experiments in the field, as detailed in the bibliography for Ref. 9
above. All of this research comes about
as a direct result of interaction with experimentalists, and such interaction
will remain a central motivation for my research in the future.
Results
of interest for the clean-limit case include
·
A low-temperature
specific heat proportional to T2 for both phases, which is
unusual for an order parameter
containing point nodes;
·
A low-energy
density of states proportional to E/Δ for both phases,
again
unusual for an order parameter containing point nodes;
·
A finite density
of states for the A-phase at E=Δ, unlike the logarithmic
singularity often associated with nodal superconductivity; and
·
An isotropic
superfluid density for the A-phase and an anisotropic superfluid
density for the B phase.
Results
for the impurity case indicate a sharp decrease in Tc for small
impurity concentrations, along with a strong increase in the zero-energy density
of states. Both of these results are
reminiscent of d-wave superconductivity.
I
have also performed calculations of the upper critical field Hc2 for
PrOs4Sb12, as well as the heavy-fermion superconductor
CeCoIn5. For CeCoIn5,
calculations indicate the possibility of a Fulde-Ferrell-Larkin-Ovchinnikov
(FFLO) state in this material at very low temperature (T < 0.7 K).
In
the future, I would like to expand my research to include calculations of dual order
parameters (superconductivity and density wave) in d-wave superconductivity, as
outlined in reference 13 above. Such
calculations hold the promise of unifying the understanding of the pseudo-gap
and superconducting phases of the cuprates, and potentially deepening our basic
understanding of these materials. I
would also apply many-body techniques, such as quantum field theory and the
renormalization group, to help construct a microscopic theory of these materials.
Another
interest I hope to pursue is quantum information theory, an area I have
recently begun working in under Prof. Todd Brun. Specifically, I am working on the problem of
quantifying non-bipartite entanglement, a problem gaining significance as the
importance of entanglement to quantum computing becomes more apparent. Bipartite entanglement, or the entanglement
of two subsystems which together comprise an entangled system, is well
understood; however, a general theory of entanglement has not yet been
developed.
The
problems of d-wave superconductivity and non-bipartite entanglement comprise
two of the biggest challenges in condensed-matter physics and quantum
information theory today. In all these
inquiries I would make contact with recent experiments as an essential source
of information, and indeed as a test bed within which to assess theoretical
work. Condensed matter physics, due to
the complexity of the systems involved, is perhaps the most data-driven area of
physics, and I look forward to much active and ongoing contact with experimentalists
in my research endeavors.
Statement of Teaching Philosophy
My
basic approach is rather simple: Teach
intuition first, so that students are not lost by advanced concepts. Give examples everyone can relate to. Make it real.
Then begin to introduce the concepts that one wants the students
to learn. Always tie concepts to
examples and circumstances so that the push to abstraction happens gradually
and students are not lost.
My
teaching experience at USC has included teaching several laboratories,
including general education (physics for non-science majors), modern physics
(optics and quantum mechanics), electricity and magnetism, and physics for
pre-medical students. I have also
conducted tutoring sessions. In all
these experiences I have found the following question to be the useful,
operative one: At what level should the
students understand the material? This
is best illustrated by an example. The
question has been posed to me: why do planets orbit the Sun, instead of hitting
the Sun? To simply reply, “angular
momentum conservation” is clearly insufficient for a student, such as the
non-science major, whose class has never defined the vector product. This student will not have a conceptual
understanding of angular momentum. An appeal
to intuition is necessary, using common experience as a reference. I pose the question, “Well, why do things
fall?”
“Gravity,” comes back the answer.
“All right,” I say, “what happens when a
pitcher throws a pitch?”
“It falls.”
“Does it move forward?”
“Yes.”
“So what happens if he throws it really,
really, really hard?”
“It moves forward a lot.”
From
here the conceptual leap to the concept of an orbit is small, and the intuition
that planets are, in essence, falling around the Sun becomes easy to
acquire. For the more advanced student,
one may then present the notion that things that are rotating, or revolving
around things, tend to stay that way, for the same reason that things in linear
motion tend to stay in linear motion.
For
a more advanced course, perhaps one attended by engineering or science
students, I might introduce the notion of a central force and point out that if
the gravitational force and velocity vector are not parallel, the sideways
motion of the planet will tend to carry it around the Sun. Only then would I quantify this motion by
introducing the concept of angular momentum.
In my experience, students need to connect to the material at some real,
basic, pre-conceptual level before they can be expected to master difficult
concepts. Figuring out what this level
is for a given student or group of students is, I believe, the primary teaching
responsibility of the instructor. I will
illustrate this by another example.
I
am often asked by my students, “What is superconductivity?” I could answer in terms of electrical
resistance, Cooper pairs, etc. But a
better way is to ask, “Do you know how a toaster works?” Everyone has experience using toasters. Once the student understands that toasters
function, in essence, because the electrons run into things, and this “banging
around” creates heat, I can talk about how at low temperatures, there is less
motion of everything, and, in essence, less for electrons to run into. Such a description, while of course grossly
oversimplified, forms the beginning of an understanding of the circumstances of
superconductivity, without introducing concepts such as phonons, Cooper pairs,
phase coherence, or order parameters.
Another
key factor is engaging, and relating to, the students. Students will arrive at understanding much
more quickly in the back-and-forth of a dialogue, as described above, than in
the simple repetition of an answer, particularly one learned ten or twenty
years before. This is particularly true
if as a teacher I present myself as a human being, neither infallible nor
omniscient, and deal with the students in the same way. It is the questions that, out of fear,
students never ask that are often the best, most insightful ones. If students are encouraged to ask and answer
questions and think for themselves, they will view learning as a pleasure,
rather than a chore. They will acquire a
capacity for wonder and fascination in physics.
Helping students find such a capacity is the highest achievement of any
teacher.