TY - JOUR
T1 - Scanning tunneling spectroscopy and break junction spectroscopy on iron-oxypnictide superconductor NdFeAs(O0.9F0.1)
AU - Sugimoto, A.
AU - Ekino, T.
AU - Ukita, R.
AU - Shohara, K.
AU - Okabe, H.
AU - Akimitsu, J.
AU - Gabovich, A. M.
N1 - Funding Information:
We thank the Natural Science Center for Basic Research and Development, Hiroshima University for supplying liquid helium. This research was supported by Grant-in-Aid for Scientific Research (No. 19540370 ) from JSPS, Japan. A.M.G. highly appreciates the 2009 Visitors Program of the Max Planck Institute for the Physics of Complex Systems (Dresden, Germany).
PY - 2010/11/1
Y1 - 2010/11/1
N2 - Iron-oxypnictide superconductor NdFeAs(O0.9F0.1) was studied using both low-temperature scanning tunneling microscopy/spectroscopy (STM/STS) and tunnel break junction (BJ) methods. STM topography showed granular and spot structures with a typical size of several nanometers, most probably governed by fluorine atom distribution. The majority of STS conductance, G, versus voltage, V, curves revealed V-shaped structures, whereas some of G(V) dependences possessed coherent gap peaks or kinks at gap energies. At the same time, G(V) dependences obtained by the BJ technique showed clear-cut coherence peaks with peak-to-peak distances Vpp = 4Δ/e ∼ 25 mV at 4.2 K, where Δ is the superconducting energy gap, e > 0 is the elementary charge. This yields Δ(0) = 6-7 meV, so that the ratio 2Δ(0)/k BTc is about 3-4, kB being the Boltzmann constant. This value is consistent with the conventional weak-coupling s-wave Bardeen-Cooper-Schrieffer theory.
AB - Iron-oxypnictide superconductor NdFeAs(O0.9F0.1) was studied using both low-temperature scanning tunneling microscopy/spectroscopy (STM/STS) and tunnel break junction (BJ) methods. STM topography showed granular and spot structures with a typical size of several nanometers, most probably governed by fluorine atom distribution. The majority of STS conductance, G, versus voltage, V, curves revealed V-shaped structures, whereas some of G(V) dependences possessed coherent gap peaks or kinks at gap energies. At the same time, G(V) dependences obtained by the BJ technique showed clear-cut coherence peaks with peak-to-peak distances Vpp = 4Δ/e ∼ 25 mV at 4.2 K, where Δ is the superconducting energy gap, e > 0 is the elementary charge. This yields Δ(0) = 6-7 meV, so that the ratio 2Δ(0)/k BTc is about 3-4, kB being the Boltzmann constant. This value is consistent with the conventional weak-coupling s-wave Bardeen-Cooper-Schrieffer theory.
KW - Iron-pnictide superconductor
KW - STM
KW - Tunneling spectroscopy
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U2 - 10.1016/j.physc.2010.05.038
DO - 10.1016/j.physc.2010.05.038
M3 - Article
AN - SCOPUS:77957920861
SN - 0921-4534
VL - 470
SP - 1070
EP - 1072
JO - Physica C: Superconductivity and its Applications
JF - Physica C: Superconductivity and its Applications
IS - 20
ER -