Π-Stacked (Cn-C6H6–Fe–C6H6–C13-n)n=2: A spin operated thermoelectric nanodevice. (November 2022)

• Record Type: Journal Article
• Authors: Mitra, Shankar Prasad; Bhowmick, Rinki; Biswas, Ajit; Chattopadhyaya, Mausumi; Koley, Sayantanu; Sen, Sabyasachi
• Is Part Of: Journal of physics and chemistry of solids. Volume 170(2022)
• Publication Date: 2022-11
• Subjects: Spin caloritronics -- Spin seebeck effect -- π-stacked system -- Thermoelectric figure of merit; Solids -- Periodicals; Solides -- Périodiques; Solids; Periodicals; 530.41
• DOI: 10.1016/j.jpcs.2022.110900
• Languages: English
• ISSNs: 0022-3697

Abstract

Abstract: Harvesting waste heat back into electricity by exploiting the temperature difference across two ends of a nanodevice and its concomitant spin dependence has led to the emergence of a new field known as spin caloritronics. Herein, we report the spin polarized thermoelectric features in a π-stacked system comprised of (Cn -C6 H6 –Fe–C6 H6 –C13-n )n = 2 . A decisive factor, the Seebeck coefficient, becomes fully spin dependent on temperature and switches from positive to negative values, which illustrates the switching of the thermoelectric behavior from a p-to n-type due to the change in the spin state from spin-down to spin-up. A relatively large thermoelectric figure of merit has been reported in the case of the spin figure of merit of the system. In this context, three major observations have been made: i) The Seebeck coefficient has a distinctive feature over two different spin channels, ii) the spin Seebeck coefficient (Ss ) is nearly four times larger than the charge Seebeck coefficient (Sc ), and (iii) the spin thermoelectric figure of merit (ZS ) rises by 80% with respect to charge thermoelectric figure of merit (ZC ) under thermal bias. Our results have been well explained through the analysis of temperature dependent transmission spectra of the system. The emergence of a relatively large spin Seebeck coefficient allows us to measure the pure spin current of the system as well as extending the devices application from simple memory (MRAM) devices to on-chip energy harvesting systems. Graphical abstract: Variation in the spin and charge thermoelectric figure of merit and spin dependent Seebeck coefficient with thermal bias. Image 1 Highlights: A clean and green energy solution to the massive waste heat generated in a circuit is thermoelectric materials. Modification in thermoelectric feature against the spin polarization of tunneling electron has developed a new but virgin domain of Spincaloritronics. Thermoelectric features are analysed mainly through ZT, spin polarized electrical conductivity, spin polarized Seebeck coefficient, In Spincaloritronics, one would have separate figure of merit for charged part and spin part as well as separate charge and spin Seebeck coefficient. On an average Spin Seebeck coefficient (Ss ) is approximately four times larger than its charge counterpart (Sc ) and there is nearly 80% rise in ZS from ZC . Most, significant observation is switching in thermospin behavior from n to p type due to spin reversal. Dissimilar behavior over two different spin channels certainly exemplify the appearance of spin dependent Seebeck effect with switching action from p to n type due to spin reversal.