Phillips J C
Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974, USA.
Proc Natl Acad Sci U S A. 1997 Sep 30;94(20):10532-5. doi: 10.1073/pnas.94.20.10532.
The threshold behavior of the transport properties of a random metal in the critical region near a metal-insulator transition is strongly affected by the measuring electromagnetic fields. In spite of the randomness, the electrical conductivity exhibits striking phase-coherent effects due to broken symmetry, which greatly sharpen the transition compared with the predictions of effective medium theories, as previously explained for electrical conductivities. Here broken symmetry explains the sign reversal of the T --> 0 magnetoconductance of the metal-insulator transition in Si(B,P), also previously not understood by effective medium theories. Finally, the symmetry-breaking features of quantum percolation theory explain the unexpectedly very small electrical conductivity temperature exponent alpha = 0.22(2) recently observed in Ni(S,Se)2 alloys at the antiferromagnetic metal-insulator transition below T = 0.8 K.
在金属 - 绝缘体转变附近的临界区域中，随机金属输运性质的阈值行为受到测量电磁场的强烈影响。尽管存在随机性，但由于对称性破缺，电导率呈现出显著的相位相干效应，与有效介质理论的预测相比，这极大地锐化了转变，正如之前对电导率所解释的那样。这里的对称性破缺解释了Si(B,P)中金属 - 绝缘体转变的T→0磁导率的符号反转，这也是有效介质理论之前无法理解的。最后，量子渗流理论的对称性破缺特征解释了最近在T = 0.8 K以下反铁磁金属 - 绝缘体转变时Ni(S,Se)2合金中意外出现的非常小的电导率温度指数α = 0.22(2)。
