Alberto Morpurgo

2D materials are crystals only one or a few atom thick, with unique properties, different from those of their bulk parent compounds. 2D materials hosting magnetically ordere phases have been introduced only recently and their exploration –mainly based on exfoliated layers– has only just started. A critical issue is that exfoliated atomically thin layers contain a very small amount of material, so that the majority of commonly employed techniques to probe magnetism are not sufficiently sensitive and cannot be applied. In this talk I will present work that we did on a variety of 2D magnetic semiconductors, in which we used transport measurements in different configurations, to probe magnetism in these systems. I will first overview studies on a first generation of compounds (including CrI$_3$ , CrCl$_3$ , different phases of CrBr$_3$ , MnPS$_3$ , and more) that have relied on using atomically thin layers as tunnel barriers, through which tunnelling magnetotransport is measured as a function of field and temperature. I will show how these measurements allow the magnetic phase diagram to be mapped in detail for layered antiferromagnets, for intralayer antiferromagnets, as well as for ferromagnets. I will then discuss a second generation of experiments based on 2D magnetic semiconductors (such as CrSBr and CrPS$_4$ ) in which the width of the conduction band is sufficiently large (1 eV or larger) to enable the realization of field effect transistors at low temperature. I will show how in these devices the gate voltage can be used to tune electrostatically magnetotransport as well as the magnetic state of the systems. I will conclude by providing a short outlook for future experiments and new phenomena that can be explored in these materials.

Acknowledgements
I acknowledge all my PhD student, Postdocs and collaborator in Geneva and outside. In particular in Geneva: Zhe Wang, Fan Wu, Nicolas Ubrig, Marco Gibertini, Ignacio Gutierrez, Enrico Giannini, Fabian von Rohr, Sara Lopez. Outside Geneva: Patrick Maletinsky, Atac Imamoglu, David Mandrus and their collaborators.