Proximity induced longitudinal and transverse thermoelectric response in graphene-ferromagnetic CrBr₃ vdW heterostructure

Abstract

The integration of longitudinal and transverse thermoelectric fosters various new opportunities in tuning the charge transport behaviour and opens a platform for efficient thermopower devices. The presence of asymmetric electronic structure supposed to accomplish large thermopower and electronic figure of merit. Herein, we investigate magnetic proximity coupled longitudinal and transverse thermoelectric behaviour in heterostructure of monolayer semimetal, graphene and a monolayer ferromagnet, CrBr3 under the framework of ab initio-based calculations and employed constant relaxation time approximation (CRTA).The integrated density of states is elevated and asymmetric near Fermi energy region due to seamless proximity integration, depicting mixed character of graphene and CrBr3.The asymmetric nature of electronic structure significantly affects the Seebeck coefficients (S) and electrical conductivity (σ/τ) of heterostructure. The consistent step-like conductance spectrum influences interfacial polarization due to agile proximity integration. The magnitude of Seebeck coefficient (S) is found to be 653µV/K near Fermi level. The heterostructure observes higher electrical conductivity and power factor in n-type region of the order of 106 S/m and 1020 cm-3at room temperature. The dimensionless electronic figure of merit (ZTe) advocates the heterostructure system to be an ideal thermoelectric material. Alongside longitudinal thermoelectric, we also find the heterostructure system is sensitive to anomalous Nernst effect (transverse thermoelectric) with oscillatory nature. The Seebeck and anomalous Nernst effect (ANE) shows high degree of tunability with applied external electric field. The synergistic existence of Seebeck and ANE due to proximity integration in vdW atomic crystal at room temperature will provide realistic approach to experimentally fabricate and develop real-time thermopower devices.

Twist Proximity-Endowed Large Figure of Merit in a Band-Modulated CrI3/1T-MoS2 Moiré Superlattice

“…The pristine 1T-MoS 2 exhibits high thermoelectric performance with a Seebeck coefficient value of 85.6 μV/K . Further, 2D ferromagnetism in the CrI 3 layer offers wide bandgap spin transport pathways along with peculiar physical properties, thermoelectric properties, and robust proximity effect. − ML-CrI 3 is reported to be a potential candidate for TE application, which exhibits a Seebeck coefficient value of 291 μV K –1 at 800 K and the figure of merit of the order 0.95 and 1.57. , The proximity effect between the adjacent CrI 3 and MoS 2 layers is expected to be further enhanced upon being subjected to the twist effect. The twisted heterostructure hosts macroscopic TE characteristics via local electronic structure manipulation.…”

Large thermoelectric transport in magnetically coupled CrI3/1T-MoS2 vdW heterostructure via spin–charge interconversion

“…In order to overcome these challenges and realize controlled optimum TE performances, an effective approach is to design a low-dimensional van der Waals (vdW) heterostructure. Consequently, vdW heterostructures of nonmagnetic metals with ferromagnetic material can provide an ideal platform to explore spin-charge interaction via the magnetic proximity effect (MPE) [19][20][21][22][23][24][25][26][27]. The transport of spins from magnetic material to nonmagnetic metal through the interface can give rise to SSE.…”

“…In this regard, vdW systems with high-quality interfaces can provide a single platform to realize magnetism-derived TE behavior via the MPE. For example, previously reported non-MPE vdW heterostructures exhibit unique electronic structures with enhanced TE properties [1,6,11,[19][20][21][32][33][34][35][36][37][38][39][40][41][42]. As compared to their individual monolayers (MLs).…”