Vacancies in Fe3GeTe2
Fe-vacancy-driven noncollinear magnetism in a van der Waals ferromagnet monolayer
collaborators: Prof. Biplab Sanyal (Uppsala University), Prof. Phani Motamarri
Manuscript in preparation.
Fe3GeTe2 is a layered van der Waals ferromagnet that remains magnetic down to a single layer, making it a leading candidate for two-dimensional spintronics. Its magnetic properties are known to be sensitive to Fe deficiency, but a microscopic picture of how individual vacancies reshape the local magnetism has been missing. Answering this question requires large supercells together with a fully relativistic, noncollinear treatment of magnetism, a combination that has been computationally out of reach.
Using the methods developed in this thesis, we carried out large-scale, fully relativistic noncollinear DFT calculations of Fe vacancies in monolayer Fe3GeTe2. We study:
- which of the two inequivalent Fe sublattices vacancies prefer to form on;
- how a vacancy reconstructs the magnetic moments of the surrounding Fe atoms and how far this disturbance extends;
- the vacancy-induced canting of the spins away from the collinear ferromagnetic order;
- how pairs of vacancies interact with each other.
These calculations connect the composition sensitivity of Fe3-xGeTe2 to a microscopic picture of defect formation and local magnetic order, and provide a reference for future studies of supported layers and heterostructures.
