Abstract
The Anderson insulating states in Au nanoparticle assembly are identified and studied under the application of magnetic fields and gate voltages. When the inter-nanoparticle tunneling resistance is smaller than the quantum resistance, the system showing zero Mott gap can be insulating at very low temperature. In contrast to Mott insulators, Anderson insulators exhibit great negative magnetoresistance, inferring charge delocalization in a strong magnetic field. When probed by the electrodes spaced by ~200 nm, they also exhibit interesting gate-modulated current similar to the multi-dot single electron transistors. These results reveal the formation of charge puddles due to the interplay of disorder and quantum interference at low temperatures.
Highlights
The pioneer work by Mott pointed out the Coulomb interactions plays an important role in the electron conduction in a three-dimensional lattice, governed by the lattice constant
Such staircase structures would result in resonance-like peaks in the dynamical conductance dI/dVb curve as in structures would result in resonance-like peaks in the dynamical conductance dI/dVb curve as in Figure 10b Again, we found that these resonance peaks become smeared as the magnetic field is Figure 10b Again, we found that these resonance peaks become smeared as the magnetic field is elevated up to 0.5 T
Our work revealed the important transport properties of an Anderson insulator, which is achievable by controlling the tunneling resistance RT ~RK in an NP assembly with finite disorder
Summary
The pioneer work by Mott pointed out the Coulomb interactions plays an important role in the electron conduction in a three-dimensional lattice, governed by the lattice constant. Initial theoretical investigation employing scaling theory concluded that disorder, no matter how weak, would trap charge carriers and convert any 2D metal into an insulator [4]. Against this view, Kravchenko reported an apparent MIT in 2D by measuring charge transport in silicon field-effect transistors by varying electron density [5]. Kravchenko reported an apparent MIT in 2D by measuring charge transport in silicon field-effect transistors by varying electron density [5] This “plane mystery” attracts many theoretical and experimental efforts to unveil any exotic metallic phases [6]
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