Spin-polarized transport through the Kondo-lattice 2-D vdW ferromagnets Fe_nGeTe₂

The emerging generation of 2D vdW ferromagnets, specifically the compounds denoted as Fe_nGeTe₂ (with n=3, 4), holds great promise for realizing low-power spintronics. These ferromagnetic materials exhibit ferromagnetic behavior at nearly room temperature, possess excellent electrical conductivity, and can be seamlessly integrated with other materials due to their layered structure. This makes them highly relevant for efficient applications in the field of spintronics. Through point contact spectroscopy (PCS) and scanning tunneling microscopy/spectroscopy experiments (STM/S), we have provided evidence of the simultaneous existence of a highly spin-polarized Fermi surface and Kondo lattice behavior in these ferromagnets. Our PCS findings, involving mesoscopic junctions between these itinerant ferromagnets and conventional superconductors, demonstrate the ability of both ferromagnets to generate highly spin-polarized transport current. Spectroscopic measurements have revealed the presence of a hybridization gap, indicating the existence of heavy Fermionic characteristics in these systems. Due to the unique coexistence of itinerant ferromagnetism and heavy Fermionic behavior, the Fe_nGeTe₂ family possesses the potential to give rise to novel quantum phenomena when their physical properties are allowed to interact with other quantum orders through material heterostructuring.