Pairing symmetry of CeCoIn5 detected by inplane torque measurements Carmen C. Almasan, Kent State Un

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Pairing symmetry of CeCoIn5 detected by in-plane
torque measurements Carmen C. Almasan, Kent
State University, DMR 0406471

Controversial nodal position? Torque bulk
measurement, angle sensitive.
It has been established that the superconducting
order parameter of the heavy fermion CeCoIn5
displays d-wave symmetry. However, the direction
of the gap nodes relative to the Brillouin zone
axes, which determines the type of d-wave state,
namely dx2-y2 or dxy is still an extremely
controversial open question. We have
addressed this extremely controversial issue
through an experimental technique that allows the
direct measurement of the nodal positions, i.e.,
torque measurement. The reversible part of the
angular dependent mixed-state torque data,
obtained after subtracting the corresponding
normal-state torque, shows a four-fold symmetry
with a positive amplitude (see top figure to the
right). Sharp peaks in the irreversible torque
data were observed at 45, 135, 215, 3050 etc (see
bottom figure to the right). The symmetry of the
fee energy extracted from the four-fold symmetry
of the mixed-state reversible torque coupled with
the position of the sharp peaks in the
irreversible torque point unambiguously towards
dxy wave symmetry in CeCoIn5. Further support for
the dxy wave symmetry is provided by the magnetic
field and temperature dependence of the
mixed-state reversible torque.
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Pairing symmetry of CeCoIn5 detected by in-plane
torque measurements Carmen C. Almasan, Kent
State University, DMR 0406471

• Education

Outreach Activities
As part of the outreach activities of the PI, AP
and Honors Physics students from nearby high
schools visited her laboratory And learned about
physics in general and superconductivity and
magnetism in particular, through demonstrations
and short lectures given by the PI and her
students. In this way, the high School students
were exposed to a research environment and were
given a flavor of the science done in the lab and
the technology involved in going it. In
addition, the PI is involved in the Young
Womens Summer Institute, which is a competitive
program across Ohio for middle school girls,
held on the Kent State University Campus. During
this program, middle school girls are exposed to
science experiments and interact with female
scientists at different stages in their career,
I.e., undergraduate and graduate students, and
faculty.

• Yankun Tang, Postdoctoral Researcher joined the
• group in September 2006.
• Parshu Gyuali, Ph.D. student
• Tao Hu, Ph.D. student
• Xiao Hong, Ph.D. student

The graduate student Tao Hu (left) and
post-doctoral researcher Yankun Tang (right)
transfer liquid helium in preparation for the
transport measurements.