A tale of three atoms displaying ferroelectric, ferrimagnetic and altermagnetic order

When developing new materials, scientists synthetize and test novel compounds with uncharted chemical structures, which often lead to discovery of groundbreaking material properties and sometimes even new physics. In this seminar I will discuss a scientific journey with just three atoms: Germanium, Manganese and Tellurium. By doping the simplest room-temperature ferroelectric, GeTe, with Manganese, the system develops complex multiferroic exchange interactions with competing ferromagnetic, antiferromagnetic, and antisymmetric exchange, also known as the Dzyaloshinskii–Moriya interaction. Thereby combining magnetism with topological properties inherited from Rashba-type spin-splitting in the host GeTe. Finally, I will briefly discuss MnTe, a special antiferromagnet that we recently addressed in the context of altermagnetism – as a central topic of condensed-matter physics demonstrating lifted Kramers spin degeneracy. The seminar is based mainly on experimental results from spin- and angle resolved photoemission spectroscopy and x-ray magnetic circular dichroism experiments carried out at Swiss Light Source, which I briefly introduce along with the beam lines where these experiments were carried out.