Atomic-layer controlled THz Spintronic emission from Epitaxially grown Two dimensional PtSe$_2$/ferromagnet heterostructures

TL;DR

This paper demonstrates the control of terahertz spintronic emission using epitaxially grown PtSe$_2$/ferromagnet heterostructures, highlighting layer-dependent effects and underlying mechanisms like inverse Rashba-Edelstein and spin Hall effects.

Contribution

It introduces epitaxial growth of PtSe$_2$/ferromagnet heterostructures as a novel THz emitter with tunable emission based on layer thickness and electronic structure.

Findings

Layer-dependent THz emission controlled by SCC mechanisms.

Transition from Rashba-Edelstein to spin Hall effect with increasing layers.

High-quality epitaxial growth of PtSe$_2$ confirmed.

Abstract

Terahertz (THz) Spintronic emitters based on ferromagnetic/metal junctions have become an important technology for the THz range, offering powerful and ultra-large spectral bandwidths. These developments have driven recent investigations of two-dimensional (2D) materials for new THz spintronic concepts. 2D materials, such as transition metal dichalcogenides (TMDs), are ideal platforms for SCC as they possess strong spin-orbit coupling (SOC) and reduced crystal symmetries. Moreover, SCC and the resulting THz emission can be tuned with the number of layers, electric field or strain. Here, epitaxially grown 1T-PtSe$_2$ and sputtered Ferromagnet (FM) heterostructures are presented as a novel THz emitter where the 1T crystal symmetry and strong SOC favor SCC. High quality of as-grown PtSe$_2$ layers is demonstrated and further FM deposition leaves the PtSe$_2$ unaffected, as evidenced with extensive characterization. Through this atomic growth control, the unique thickness dependent electronic structure of PtSe$_2$ allows the control of the THz emission by SCC. Indeed, we demonstrate the transition from the inverse Rashba-Edelstein effect in one monolayer to the inverse spin Hall effect in multilayers. This band structure flexibility makes PtSe$_2$ an ideal candidate as a THz spintronic 2D material and to explore the underlying mechanisms and engineering of the SCC for THz emission.