在研究絕緣態準晶Al70.5Pd21(Re1-xMnx)8.5的微觀結構和電導率之間的關係後，我們發現製作過程造成的成分變化以及任何在樣品中的金屬相都可能影響電阻比
R=R(4.2k)/R(300K)，後者可能也是造成絕緣態準晶在T=0 K的電導率不為0的主要因素。仔細研究絕緣態準晶Al70.5Pd21(Re1-xMnx)8.5 x=0, 0.1在低溫下的電導率和磁阻，我們發現這兩個絕緣態準晶在低溫下的電子都會經由可變程跳躍(variable range hopping; VRH)的過程傳導，但是單從電導率的量測，我們無法確定低溫下的電子傳輸是遵循Mott VRH傳導或是Efros-Shklovskii VRH(ES VRH)傳導。結合軌域負磁阻理論和波函數縮收理論來分析磁阻數據，我們清楚觀察到當溫度下降時出現Mott VRH傳導變為ES VRH傳導的轉變，而當樣品掺雜Mn之後，轉變的溫度是較高的。我們也發現Rapp等人不能觀察到傳導方式轉變的原因是因為在分析正磁阻數據時，忽略了負磁阻的貢獻。

After studying the relationship of the microstructure and the electric conductivity of insulating Al70.5Pd21(Re1-xMnx)8.5 quasicrystals (QCs), we found that both the variation of composition caused by sample preparation process and any secondary metallic phase in the sample might affect the determined resistivity ratio
R=R(4.2K)/R(300K),and the latter may also be the main factor which leads to the non-zero conductivity of insulating QC’s at T=0K. The electric conductivity and the magnetoresistance (MR) of insulating Al70.5Pd21(Re1-xMnx)8.5 QC’S with x = 0 and x = 0.1 at low temperatures were studied in detail. We found that the electric conduction at low temperatures in these two insulating QC’s was all via variable range hopping (VRH) processes); but from electric conductivity measurements only, one cannot ascertain whether the electrons transport follows Mott VRH or Efros-Shklovskii VRH (ES VRH) law at low temperatures. By analyzing the MR data combining the MR theories of the forward interference and the wave-function shrinkage, we clearly observed that there is a crossover from Mott VRH conduction to ES VRH conduction as the temperature is lowered; and the crossover temperature is higher in the sample doped with Mn. We also found that the reason that Rapp et al. did not observe the crossover conduction was due to ignoring the negative MR contribution in analyzing the positive MR data .

1. Q.Guo, and S. J. Poon, Phys. Rev. B 54, 12793 (1996)
2. C. R. Wang, H. S. Kuan, S. T. Lin, and Y. Y. Chen, J. Phys. Soc. Jpn.
67, 2383(1998)
3. C. R. Wang, S. T. Lin, J. Phys. Soc. Jpn. 68, 3988(1999)
4. 吳世文學長的論文，國立成功大學(2001)
5. T. I. Su, C. R. Wang, S. T. Lin, and R. Rosenbaum, Phys. Rev. B 66,
054438 (2002).
6. H. C. Fang, T. I. Su and S. T. Lin, J. Non-Cryst. Solids 334, 417 (2004)
7. 曾至國學長的論文，國立成功大學(2003)
8. V. Srinivas, M. Rodmar, S. J. Poon, and O. Rapp, Phys. Rev. B 63,
172202 (2001).
9. O. Rapp, V. Srinivas, and S. J. Poon, Phys. Rev. B 71, 012202 (2005).
10. M. Ahlgren, C. Gignoux, M. Rodmar, C. Berger, and O. Rapp, Phys.
Rev. B 55, R11915
11. M. Rodmar, F. Zavaliche, S. J. Poon, and O. Rapp, Phys. Rev. B 60,
10807 (1999).
12. M. Rodmar, D. Oberschmidt, M. Ahlgren, C. Gignoux, J. Delahaye,
C. Berger, S. J. Poon, and O. Rapp, J. Non-Cryst. Solids 250, 883 (1999).
13. V. Srinivas, M. Rodmar, R. Konig, S. J. Poon, and O. Rapp, Phys. Rev. B 65, 094206 (2002).
14. O. Rapp, V. Srinivas, P. Nordblad, and S. J. Poon, J. Non-Cryst. Solids 334, 356 (2004)
15. P. Hernandez and M. Sanguer, Phys. Rev. Lett. 68, 1402 (1992).
16. R. Rosenbaum, A. Milner, S. Hannahs, T. Murphy, E. Palm, and
B. Brandt, Physica B 294-295, 340 (2001).
17. V. L. Nguyen, B. Z. Spivak, and B. I. Shklovskii, Zh. Eksp. Teor. Fiz.
89, 1770 (1985) [Sov. Phys. JETP 62, 1021 (1985)].
18. U. Sivan, O. Entin-Wohlman, and Y. Imry, Phys. Rev. Lett. 60, 1566 (1988); U. Entin- Wohlman, Y. Imry, and U. Sivan, Phys. Rev. B 40, 8342(1989).
19. R. Rosenbaum, Phys. Rev. 63 (2001) 094426
20. H. Tokumoto, R. Mansfield, and M. J. Lea, Philos. Mag. B 46, 93 (1982)
21. B. I. Shklovskii, Fiz. Tekh. Poluprovodn. 17, 2055 (1983) [ Sov. Phys. Semicond. 17, 1311 (1983)].
22. W. Schoepe, Z. Phys. B：Condens. Matter 71, 455 (1988).
23. A. L. Pope, R. Schneidmiller, J. W. Kolis, and Terry M. Tritt, Phys. Rev. B 63, 052202(2001).
24. J. Delahaye, C. Gignoux, T. Schaub, C. Berger, T. Grenet, A. Sulpice , J.J. Pr_ejean, and J.C. Lasjaunias, J. Non-Cryst. Solids 250, 878 (1999)
25. R. L. Rosenbaum, B. Grushko, and B. Przepiorzynski, Journal of low temperature Physics, vol. 142
26. K. Kirihara , T. Nagata , K. Kimura, J. Alloys Comp. 342, 469 (2002)
27. Y. Honda et la., Jpn. J. Appl. Phys. 33, 4929 (1994)