Absence of ferromagnetism in MnBi 2 Te 4 / Bi 2 Te 3 down to 6 K

We successfully fabricated a ${\mathrm{MnBi}}_{2}{\mathrm{Te}}_{4}/{\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ heterostructure by incorporating Mn and Te inside the topmost quintuple layer of ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$, as unambiguously confirmed by low-energy electron diffraction $I\text{\ensuremath{-}}V$ and scanning transmission electron microscopy measurements. The surface-state Dirac cone of the heterostructure showed little change compared to that of pristine ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$, and x-ray magnetic circular dichroism measurements showed that the system was paramagnetic down to 5.6 K. These results are in contrast to previous works on related materials that showed magnetic order around 10 K as well as theoretical predictions and suggest the intricacy of the magnetic properties of two-dimensional van der Waals magnets.