, The Ames Laboratory and Iowa State University
[Host: Seunghun Lee]
The quantum critical point (QCP), where the transitions occur at absolute zero temperature, usually induces a new phase, such as unconventional superconductivity in organic, cuprate, heavy fermion and Fe-based superconductors. Whether the quantum critical point still exists beneath the superconducting phase is a long-standing question, but very tricky task since most of physical and magnetic properties are useless inside of superconducting phase. Here we have measured the zero-temperature penetration depth in BaFe2
by using tunnel diode resonator technique and identified the existence of the QCP beneath the superconducting dome . In addition, the low-temperature analysis of the penetration depth measurements revealed that the superconducting gap structure shows a universal dome-like evolution as the dopant concentration increases. The details of experimental and theoretical consideration will be discussed.
 K. Hashimoto, Kyuil Cho, et al., Science 336, 1554 (2012).
Condensed Matter Seminar
Thursday, October 18, 2012
Physics Building, Room 204
Note special room.
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