Presentation on theme: "The Low-Temperature Specific Heat of Chalcogen- based FeSe J.-Y. Lin, 1 Y. S. Hsieh, 1 D. Chareev, 2 A. N. Vasiliev, 3 Y. Parsons, 4 and H. D. Yang 4 1."— Presentation transcript:
The Low-Temperature Specific Heat of Chalcogen- based FeSe J.-Y. Lin, 1 Y. S. Hsieh, 1 D. Chareev, 2 A. N. Vasiliev, 3 Y. Parsons, 4 and H. D. Yang 4 1 Institute of Physics/National Chiao Tung University, Hsinchu 30010, Taiwan 2 Institute of Experimental Mineralogy, Cherngolovka, Moscow Region 142432, Russia 3 Department of Low temperature Physics, Moscow State University, Moscow 119991, Russia 4 Department of Physics, University of California, Santa Babara, CA 93106, USA 4 Department of Physics, National Sun Yat-sen University, Kaohsiung 804, Taiwan
Contents Introduction to Fe-based superconductors Specific heat as a probe of the superconducting order parameter Experiments and results Conclusions
A brief introduction to iron-based superconductors
70 Nb 3 Ge MgB 2 Metallic alloys LSCO YBCO TI - cuprate Hg - cuprate Cuprates e-doped LaOFeP e-doped LaOFeAs e-doped SmOFeAs Fe-based superconductors The Race to Beat Cuprates? The crusade of Room Temperature superconductors? ？
The order parameter in Fe-based superconductors remains elusive. To get insight into the pairing mechanism, it is crucial to determine the gap structure in the superconductors like FeSe or pnictides. Though with lower T c, FeSe has the simplest structure, and this very simplicity could provide the most appropriate venue of understanding both the order parameter and the superconducting mechanism of Fe-base superconductors. Motivation
Conclusions for FeSe Existence of low-energy excitations more than in an isotropic s-wave. Gap anisotropy. S + exntended s. Probably No accidental nodes. Existence of an isotropic s-wave. H c2,H//c 13.1 T and H c2,H c 27.9 T. The anisotropy in H c2 is about 2.1.
Fig. 4 The specific heat of MgB 2. The dashed lines are determined by the conservation of entropy around the anomaly and used to estimate ΔC/T c. Inset: Entropy difference ΔS by integration of ΔC/T.