Inelastic Neutron Scattering on Fe3GeTe2

Aim: Learning how to quantify magnetic exchange interactions.

Side aim: Introducing the class of 2D "correlated van-der-Waals materials".

Manuscript to be discussed:

• Calder et al., Phys. Rev. Lett. 2019

Guiding questions:

• Which material is studied and why it is relevant?
• Why is Ref. 21 of Calder's paper important? Help: Mind the Mermin-Wagner theorem. What does it imply for a 2D isotropic Heisenberg system at finite temperature? What do you conclude for the Fe3GeTe2 sytem under study?
• How does the time-of-flight INS experiment work?
• Explain the results of the experiment.