標題: Conductivity and tunneling density of states in granular Cr films
作者: Sun, Yu-Chen
Yeh, Sheng-Shiuan
Lin, Juhn-Jong
電子物理學系
物理研究所
Department of Electrophysics
Institute of Physics
公開日期: 12-八月-2010
摘要: We have measured the tunneling differential conductances, G(V), of four Al/AlO(x)/Cr planar tunnel junctions as well as the conductivities, sigma(T), of the Cr electrodes at liquid-helium temperatures. The Cr electrodes were made to be granular with dimensionless intergrain tunneling conductance spanning from g similar or equal to 1 to g >> 1, and the dimensionality of the granular array d=3. For the samples with g >> 1, we found that the measured G(V) curves display large zero-bias singularities which obey a ln V law at low bias voltages (less than or similar to a few millielectron volt) while crossing over to a root V law at high bias voltages. Simultaneously, the conductivities of the Cr electrodes reveal ln T dependence below a characteristic temperature. These results are explained in terms of the recent theory of granular metals. In a sample with g similar or equal to 1, in addition to the conductivity dependence sigma proportional to ln T, we observed a universal scaling behavior of the normalized differential conductance [G(V, T) -G(0, T)]/root T with the combined parameter root e vertical bar V vertical bar/k(B)T in a wide temperature interval of 2.5-32 K. This result is not yet understood.
URI: http://dx.doi.org/10.1103/PhysRevB.82.054203
http://hdl.handle.net/11536/32301
ISSN: 1098-0121
DOI: 10.1103/PhysRevB.82.054203
期刊: PHYSICAL REVIEW B
Volume: 82
Issue: 5
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