Beschreibung:
<jats:p>Electronic transport of ultrananocrystalline diamond involves the interplay between disorder, Anderson localization, and phase coherence. We show that variable range hopping explains many key features of the conductivity including the large low temperature negative magnetoresistance. Our numerical studies suggest two regimes where the (negative) magnetoresistance varies with magnetic field B such as B2 or B1∕2, respectively, depending on the ratio of the cyclotron orbital radius and the hopping distance. This agrees with experiment, which also points to the expected T−1∕2 temperature dependence of the hopping distance at the critical field.</jats:p>