Magnetic Frameworks and Non‐Magnetic Dopants: A Novel Strategy for Enhancing Thermoelectric Efficiency in Manganese Telluride – Mechanistic Insights into Charge Carrier Dynamics and Phonon Transport
Sri Sai Samhitha Gadhavajhala, Veera Prabu Kannan, Abhijeet J. Kale, Rohit Batra, Soumya R. Mishra, Bhuvanesh Srinivasan
Abstract
Manganese Telluride (MnTe) exhibits substantial promise for thermoelectric applications; however, its efficiency is hindered by suboptimal electrical and thermal characteristics. This study investigates the incorporation of non-magnetic zinc into the magnetic framework of MnTe, leading to an enhanced thermoelectric figure of merit by optimizing the interplay between electrical and thermal transport properties through several mechanisms: i) enhanced weighted mobility and reduced effective mass facilitate superior charge carrier dynamics, stemming from modifications to the electronic band structure and a concomitant reduction in spin-disorder scattering, particularly near the Néel transition temperature; ii) suppression of the MnTe₂ secondary phase effectively minimizes impurity scattering; iii) favorable interactions between charge carriers and phonons facilitate acoustic phonons to dominate scattering mechanisms at elevated temperatures; iv) reduced lattice thermal conductivity, attributed to three-phonon scattering, lattice anharmonicity, and effective spin-phonon coupling, further enhances overall thermoelectric efficiency. Beyond the thermoelectric aspects, this work elucidates the emergence of weak anti-localization, multichannel Kondo effects, and magneto-elastic coupling phenomena in MnTe-based materials. These findings pave the way for novel explorations in magnetic strategies for thermoelectrics, transitioning the emphasis from the conventional approach of introducing magnetic impurities in non-magnetic compounds to the enhancement of properties in inherently magnetic materials via non-magnetic dopants.