Tailoring topological properties in Weyl semimetal thin films

Recently discovered topological Dirac and Weyl semimetals are provoking an incredible interest not only because they represent a point of contact between high-energy and solid state physics, but also due to the technological perspectives they offer in the fields of electronics, spintronics, spin-caloritronics, quantum computing and energy harvesting.

Although several exceptional properties, caused by the non-trivial topology, have been observed on macroscopic single crystals, many concrete applications pass through the integration of candidate materials into nano/micro-structured devices.

To this aim, the establishment of methods to fabricate high-quality thin films and the investigation of the evolution of their topological transport properties with scaling the sample dimensions is a crucial step, but the current state of art is still strongly lacking.

In this project, I want to fabricate thin films of selected topological semimetals with different magnetic ground states (non-magnetic, ferromagnetic, non-collinear antiferromagnetic) using the pulsed-laser deposition technique and set a protocol to optimize the growing conditions.

The aim is to explore the evolution of their topological electric and thermoelectric transport properties, including anomalous Hall and Nernst effects, chiral anomalies and giant magnetoresistance, as a function of different tunable parameters (thin film thickness, sample lateral size, temperature, magnetic field, strain).

This will be achieved through a sophisticated method of sample patterning with a multiple-approach, which combines optical lithography and focused-ion-beam techniques.

In this way, I will be able to obtain highly conditioned micro/nano-structures with an optimal control over the geometrical factors.

This study will be of crucial importance to obtain at the same time a new insight into the fundamental physics of topological semimetals and a clue into the actual perspectives of transport devices.