COULOMB-GAP MAGNETOTRANSPORT IN GRANULAR AND POROUS CARBON STRUCTURES

被引:76
作者
FUNG, AWP
WANG, ZH
DRESSELHAUS, MS
DRESSELHAUS, G
PEKALA, RW
ENDO, M
机构
[1] MIT, DEPT PHYS, CAMBRIDGE, MA 02139 USA
[2] MIT, FRANCIS BITTER NATL MAGNET LAB, CAMBRIDGE, MA 02139 USA
[3] LAWRENCE LIVERMORE NATL LAB, DEPT CHEM & MAT SCI, LIVERMORE, CA 94550 USA
[4] SHINSHU UNIV, COOPERAT RES CTR, MATSUMOTO, NAGANO 390, JAPAN
[5] SHINSHU UNIV, FAC ENGN, MATSUMOTO, NAGANO 390, JAPAN
来源
PHYSICAL REVIEW B | 1994年 / 49卷 / 24期
关键词
D O I
10.1103/PhysRevB.49.17325
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
The possibility of observing a Coulomb gap due to carrier-carrier interactions in granular metallic systems is investigated, with particular emphasis on porous carbon structures such as carbon aerogels and activated carbon fibers (ACF's), both of which contain ultrafine pores and grains, the size of which can be controlled by the sample preparation procedures. The exp[-(T0/T)1/2] temperature dependence observed at low temperature in the dc electrical conductivity of both materials is characteristic of granular metallic systems. A variable-range hopping mechanism near a Coulomb gap around the Fermi level is proposed to circumvent the difficulties of previous tunneling and hopping models. The temperature dependence of the magnetoresistance in fields up to 15 T is measured for both aerogels and ACF's to further confirm the effect of the Coulomb gap. The results not only qualify porous materials as a medium for studying localization phenomena, but also shed some light on the complex problem of transport near the percolation threshold in granular metallic systems in general.
引用
收藏
页码:17325 / 17335
页数:11
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