Anomalous thermopower oscillations in graphene-nanowire vertical heterostructures

Richa Mitra, Manas Ranjan Sahu, Aditya Sood, Takashi Taniguchi, Kenji Watanabe, Hadas Shtrikman, Subroto Mukerjee, A. K. Sood, Anindya Das

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Thermoelectric measurements have the potential to uncover the density of states (DOSs) of lowdimensional materials. Here, we present the anomalous thermoelectric behavior of monolayer graphene-nanowire (NW) heterostructures, showing large oscillations as a function of the doping concentration. Our devices consist of InAs NW and graphene vertical heterostructures, which are electrically isolated by thin (∼10 nm) hexagonal boron nitride (hBN) layers. In contrast to conventional thermoelectric measurements, where a heater is placed on one side of a sample, we use the InAs NW (diameter ∼50 nm) as a local heater placed in the middle of the graphene channel. We measure the thermoelectric voltage induced in graphene due to Joule heating in the NW as a function of temperature (1.5-50 K) and carrier concentration. The thermoelectric voltage in bilayer graphene (BLG)-NW heterostructures shows sign change around the Dirac point, as predicted by Mott's formula. In contrast, the thermoelectric voltage measured across monolayer graphene (MLG)-NW heterostructures shows anomalous large-amplitude oscillations around the Dirac point, not seen in the Mott response derived from the electrical conductivity measured on the same device. The anomalous oscillations are a signature of the modified DOSs in MLG by the electrostatic potential of the NW, which is much weaker in the NW-BLG devices. Thermal calculations of the heterostructure stack show that the temperature gradient is dominant in the graphene region underneath the NW, and thus sensitive to the modified DOSs resulting in anomalous oscillations in the thermoelectric voltage. Furthermore, with the application of a magnetic field, we detect modifications in the DOSs due to the formation of Landau levels in both MLG and BLG.

Original languageEnglish (US)
Article number345201
Issue number34
StatePublished - Aug 20 2021
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Mechanics of Materials
  • Mechanical Engineering
  • Bioengineering
  • Electrical and Electronic Engineering
  • General Materials Science


  • 2D-1D
  • Density of states
  • Graphene
  • Hybrid heterostructure
  • InAs nanowire
  • Thermopower
  • Thermopower oscillation


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