Can near-field transducers control the conduction of nanoscale charges?

Near field plasmonics served as a support system for exploring single-molecule spectroscopy, quantum information processing, and quantum cavity dynamics whose critical study requires the control of light, heat and charge at the nanoscale level.

the study: Nano-heating and nanoconductivity with near-field Plasmonics: possibilities for harnessing Moiré and Seebeck effects in ultra-thin films. Image Credit: Yurchanka Siarhei / Shutterstock.com

Nanodrives and near field transformers (NFTs) allow sub-diffraction of light below the classical diffraction limit by coupling plasmonic photon modes. Article published in the magazine advanced optical materials Theoretically demonstrated that light, heat, and current can be modulated through the use of NFT as it falls on black phosphorous (BP) layers.

Moreover, the moiré physics of two films with relativistic rotation and Seebeck effect where temperature gradients were induced by an electric potential were studied. The results revealed that these methods can effectively regulate the temperature distribution with values ​​between 101 and 102 K, which is critical in many nano-devices. In addition, the directional flow of current has been manipulated, aiding in electrical switching and directing the output of power.

Moire and Seebeck effect

Nanoplasmonic science is a topic of upcoming research and is a suitable approach for producing room-temperature noisy mesoscale quantum devices (NISQ). It takes advantage of its ultra-fast dynamics and low decoherence rates of the plasmonic coupled quantum emitter. These properties are prerequisites for fabricating quantum networks, including logic gates, memories, and many others.

The moiré effect is a physical phenomenon of linear optics. Moiret patterns arise from the superimposition of two (or more) similar but slightly balanced moldings on flat (or curved) surfaces as one (or more) of the melee is rotated, translated, or exposed from the initial position. This results in a series of periodic dark/bright margins whose characteristics are determined by the period, orientation and shape of the patterned samples.

When two arrays of similar periods are overlaid, the period of the resulting pattern acts as the amplifier of the original period. The Moiré effect has been used in various fields, including microscopy, coding, feature measurement, and material stress assessment.

Recently, moiré superlattices formed due to the peculiar stacking sequences between adjacent layers in heterogeneous 2D junctions that represent an orderly modification of interlayer interactions and contribute to an additional degree of freedom to manipulate the electronic structure of 2D materials.

The Seebeck effect induces voltage and produces an electric current due to the temperature gradient. This effect is commonly used in industrial scale biosensors and solar energy harvesting to investigate this effect at the nanoscale.

Moiré and Seebeck Effects in Thin Films

Advances in cancer treatments, data storage devices, solar cell technology and photovoltaics will require heat and current manipulation at the nanoscale. In the present work, two methods for tuning current and heat in thin films using Seebeck or Moiré effects implemented by near-field plasmonics are reported.

Due to the distinct optical and thermal conductivities, ultra-thin films and transition metal dichalcogenides (TMDCs) have been considered as substrates of interest with many applications in thermoelectric and optoelectronic nanodevices. Recently, BP and phosphorene monolayers have been considered as materials for these nanodevices.

Here, thin-film BP was measured to obtain Seebeck coefficients between 102 and 103 μV per K and were comparable to TMDCs that can convert heat fluxes into electric current. Besides the Seebeck effect, the Moiré effect has also been studied in terms of scattering of light, heat and current.

The studies in this work examined how to harness the Moiré effect to control nanoscale heating and subsequent conversion to electric currents in two overlapping ultra-thin films. In particular, the current work focused on BP ultrathin films with few atomic layers based on previous reports and understanding of the benefits of BP for emerging technologies and the high degree of tuning of its optical and electrical properties.

The changes in the spatial distribution of current and temperature observed in the present work originated from the intrinsic anisotropy of the BP films, along with their strong thermoelectric response that is manifested by the extreme temperature gradients achieved by nanoscale heating with NFTs.

conclusion

To summarize, the potential of NFT to control charge conduction at the nanoscale and nanoscale heating via Seebeck and Moiré effects has been reported. In addition, the Peltier effect of Onsager reciprocal and anisotropic Seebeck coefficients was studied using a few layer of BP at high temperatures.

In addition to changes in the spatial distribution of current and temperature, the maximum values ​​of each can be adjusted based on experimental requirements. Furthermore, the possibility of vectorial output from ultra-thin films has been demonstrated using the Moiré effect.

In contrast to nanoresonators previously used for heat manipulation at the nanoscale, the use of NFT has been confirmed to be non-integrated with the media. The present work also highlighted that BP can degrade even at room temperature, altering the response of Peltier and Seebeck. Besides BP, other two-dimensional (2D) materials with similar electrical and thermal conductivity parameters were expected to be interesting candidates for further investigation.

reference

Bello, F. D., Clarke, D. D. A., Tarasenko, I., Donegan, J. F., Hess, O. (2022). Nano-heating and nanoconductivity with near-field Plasmonics: possibilities for harnessing Moiré and Seebeck effects in ultra-thin films. advanced optical materials. https://onlinelibrary.wiley.com/doi/10.1002/adom.202201358

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