AC conductivity and correlation effects in nano-granular Pt/C

  • Nano-granular metals are materials that fall into the general class of granular electronic systems in which the interplay of electronic correlations, disorder and finite size effects can be studied. The charge transport in nano-granular metals is dominated by thermally-assisted, sequential and correlated tunneling over a temperature-dependent number of metallic grains. Here we study the frequency-dependent conductivity (AC conductivity) of nano-granular Platinum with Pt nano-grains embedded into amorphous carbon (C). We focus on the transport regime on the insulating side of the insulator metal transition reflected by a set of samples covering a range of tunnel-coupling strengths. In this transport regime polarization contributions to the AC conductivity are small and correlation effects in the transport of free charges are expected to be particularly pronounced. We find a universal behavior in the frequency dependence that can be traced back to the temperature-dependent zero-frequency conductivity (DC conductivity) of Pt/C within a simple lumped-circuit analysis. Our results are in contradistinction to previous work on nano-granular Pd/ZrO2ZrO2 in the very weak coupling regime where polarization contributions to the AC conductivity dominated. We describe possible future applications of nano-granular metals in proximity impedance spectroscopy of dielectric materials.

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Author:Marc Hanefeld, Peter Gruszka, Michael HuthORCiDGND
Parent Title (English):Scientific reports
Publisher:Macmillan Publishers Limited, part of Springer Nature
Place of publication:[London]
Document Type:Article
Date of Publication (online):2021/07/26
Date of first Publication:2021/07/26
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2022/03/15
Tag:Electronic properties and materials; Materials science; Nanoscale materials
Issue:art. 15163
Page Number:9
First Page:1
Last Page:9
Open Access funding enabled and organized by Projekt DEAL.
Financial support by the Deutsche Forschungsgemeinschaft (DFG) through the priority program 1928 (Coordination Networks: Building Blocks for Functional Systems) under Grant no. HU 752/12-1 and through the project HU 752/15-1 is gratefully acknowledged. This work was conducted within the Frankfurt Center for Electron Microscopy (FCEM).
Dewey Decimal Classification:6 Technik, Medizin, angewandte Wissenschaften / 62 Ingenieurwissenschaften / 620 Ingenieurwissenschaften und zugeordnete Tätigkeiten
Licence (German):License LogoCreative Commons - Namensnennung 4.0