Bivek Pokhrel1,Chitraleema Chakraborty1,John Xiao1,Matthew Whalen1,Mark Ku1,Eric Herrmann1
University of Delaware1
Bivek Pokhrel1,Chitraleema Chakraborty1,John Xiao1,Matthew Whalen1,Mark Ku1,Eric Herrmann1
University of Delaware1
In this work, we utilize the internal valley degree of freedom in two-dimensional (2D) transition metal dichalcogenides (TMDC) to study the magnetic properties of van der Waals (vdW) ferromagnet. Semiconductor spintronics devices that rely on manipulating electronic spin for spin-based information processing and storage applications have seen significant progress over the past several decades. However, the advent of optically active 2D materials has enabled optically addressable electronic valley pseudospin degrees of freedom which have led to the concept of valleytronic devices with a wide range of applications in transport phenomenon, electrical, magnetic, and spin control. Specifically, valley manipulation has been demonstrated via a strong external magnetic field which is an essential component for creating valley-based logic gates. The recent rise of 2D vdW ferromagnets not only unlocks new methods to control such spin-valley degrees of freedom at room temperature but enables magnetic sensing via van der Waals heterostructure engineering. For example, the proximity effect can be harnessed for all-optical readout of the magnetic properties such as magnetic hysteresis, local magnetic field, domain dynamics, and the interlayer magnetic dipole, as the electronic valley transition follows the optical selection rule. Such heterostructure assembly also makes on-chip manipulation of spins and g-factor possible without the need for huge superconducting coils to generate an external magnetic field. In our work, we have assembled heterostructure of Fe<sub>3</sub>GeTe<sub>2</sub>(FGT) and mono/bi-layer MoS<sub>2 </sub>(TMDC) and study the valley Zeeman splitting and valley polarization via photoluminescence spectroscopy of MoS<sub>2</sub>/FGT heterostructure as a function of temperature. Such assembly will lead to all-optical room temperature sensing of van der Waals magnet via 2D valley degree of freedom and spin-valley polarization of 2D excitons via magnetic proximity effect of a van der Waals magnet.