Behaviour near the metal-insulator transition

Experimental investigations of the behaviour of doped semiconductors near the transition have shown the following. 

3 Value of aH plotted against log nc at the transition (Edwards and Sienko 1978). 

Assuming that occe2lh in the metallic regime, many observations support v = 1 both above and below the transition (cf. pp. 150, 157). On the other hand, calculations by Kramer and Mackinnon (cf. Chapter 1, Section 6.3) give v = 1.6, of course without electron-electron interactions. Mackinnon (private communication) suggests that interactions may result in v=l. The only 

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