Engineering novel states in van der Waals heterostructures

PhD típus: 
Fizikai Tudományok Doktori Iskola
Év: 
2020/2021
Munkahely neve: 
Department of Physics
Leírás: 

Materials with different magnetic orders and high spin orbit interactions are at the forefront of condensed matter research. Magnetic heterostructures play a crucial role in information storage, and novel concepts like spin-torque or spin orbit torque appear, where electrical control for switching magnetic domains can replace the much more complicated magnetic field control. On the other hand, spin orbit interactions enable generation of spin currents via spin Hall effect or Rashba Edelstein effect or spin to charge conversion via the inverse effects. Spin orbit interactions (SOI) also hold the promise for the electrical control of spin current, and they also lie at the heart of the generation of topological phases like quantum spin Hall effect or topological superconductivity. The combination of magnetic and spin orbit interactions lead to the new field of ExSoTronics (from Exchange and Spin Orbit interactions) and result in the formation of topological magnetic excitations, skyrmions or in novel phases of matter like the Quantum Anomalous Hall effect.

The goal of the PhD project is to develop all 2D platform for ExSoTronics devices, using magnetic and 2D materials with large SOI, graphene. These materials will be generated by mechanical exfoliation and will be combined using van der Waals stacking.  We aim for thin, few layer materials where the SOI or the magnetic properties (e.g. magnetic anisotropy) can be controlled via electric fields. The heterostructures for sensitive materials will be encapsulated in hexagonal borond nitride in a glove-box environment. Fabrication will be done using e-beam lithography and material deposition techniques. The heterostructures will be studied by low temperature magneto transport measurements, like weak localization, spin Hall effect or high frequency techniques like FMR or capacitance measurements. An ambitious goal of the project is to show a spin orbit torque switching in a SOI/FM heterostructure. This will be measured using SOT-FMR or second harmonic generation techniques.

The work is done in close collaboration with several European universities.

 

Left: Charge to spin conversion in BiTeBr, a material with large SOI. The spin current is measured via a graphene spin-valve. Right: ExSoTronics heterostructure with bilayer graphene sandwiched betwen Wse2 and Cr2Get2Te3 (courtesy of J. Fabian).

 

Elvárások: 

Knowledge of solid state physics, motivation for experimental work, English knowledge, basic programming and measurement automation experience

Állapot: 
Végleges
Témavezető
Név: 
Csonka Szabolcs
Email cím: 
csonka@zero.eik.bme.hu
Intézet: 
Institute of Physics
Beosztás: 
associate professor
Tudományos fokozat: 
Professor