Rare earth substitutions in the heavyfermion superconductor CeCoIn5 M' Brian Maple, University of Ca

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Rare earth substitutions in the heavy-fermion
superconductor CeCoIn5M. Brian Maple,
University of California, San Diego, DMR 0335173
In the intermetallic compound CeCoIn5, strong
interactions between the electrons cause them to
behave at low temperature as if their masses have
ballooned by a factor of several hundred, forming
heavy fermions. Further, at temper-atures below
2.3 K, the electrons participate in an
unconventional form of superconductivity. Typical
superconductivity is easily destroyed by small
amounts of magnetic impurities, but is less
sensitive to nonmagnetic impurities. However, we
find that adding magnetic rare earth (R) ions to
CeCoIn5 has the same effect on its
superconducting state as adding nonmagnetic rare
earth ions. The formation of the heavy fermion
state in CeCoIn5 is also comparably affected by
both types of impurities. These results indicate
that an exotic physical mechanism, likely
magnetic in nature, is responsible for
superconductivity in CeCoIn5. Nature Physics in
press
Characteristic temperatures of the (Ce,R)CoIn5
materials. The superconducting transition
tem-perature Tc and heavy fermion coherence
temperature Tcoh are suppressed by the addition
of R ions, whether or not they are magnetic. Pr,
Gd, Dy, Er, and Yb are magnetic, whereas Y and Lu
are not.
Single crystal of Ce0.1Yb0.9CoIn5. The crystal
was grown by under-graduate students in our lab
using a technique known as the flux-growth
method. By using a low melting point material as
a flux, the melting point of the material
comprising the single crystals is reduced, and
single crystals form within the melt.
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Rare earth substitutions in the heavy-fermion
superconductor CeCoIn5M. Brian Maple,
University of California, San Diego, DMR 0335173
Education Individuals at different stages of
their careers (a post-doc, a graduate student,
five undergraduates including two who
participated in the research experience for
undergraduate REU program) have been involved
in this ongoing research. Johnpierre Paglione,
the post-doc, recently accepted a faculty
position as Assistant Professor of Physics at the
University of Maryland, the graduate student,
Todd Sayles, continues to work on the project
(currently completing the investigation of the
effects of Yb doping), several of the
undergraduate students have gone on to graduate
school, while several others are still with us in
the lab.
Outreach Our lab has a strong commitment to
increasing awareness and understanding of the
importance of experimental physics to a variety
of communities. We currently administer an
advanced physics lab (Phys 133) at the University
of California, San Diego, where students are
required to plan and carry out a research
project, and then present the results to their
peers in the class. Additionally, each year we
perform regularly scheduled demonstrations at
nearby elementary schools displaying some of the
interesting aspects of low temperature physics
(including the effect of liquid nitrogen when it
is in contact with different materials.)
To the left are two of the undergraduates working
in our lab. Kevin Huang (far left) is preparing
samples for growth, while Xiao Zhang is removing
a sample from the furnace. To the right are
students at Toler Elementary School (San Diego)
experi-menting on the effects of liquid nitrogen
on a variety of materials.