The synthesis of two-dimensional van der Waals magnets
has paved
the way for both technological applications and fundamental research
on magnetism confined to ultra-small length scales. Edge magnetic
moments in ferromagnets are expected to be less magnetized than in
the sample interior because of the reduced amount of neighboring ferromagnetic
spins at the sample edge. We recently demonstrated that CrGeTe3(CGT) flakes thinner than 10 nm are hard ferromagnets; i.e.,
they exhibit an open hysteresis loop. In contrast, thicker flakes
exhibit zero net remnant field in the interior, with hard ferromagnetism
present only at the cleaved edges. This experimental observation suggests
that a nontrivial interaction exists between the sample edge and the
interior. Here, we demonstrate that artificial edges fabricated by
focus ion beam etching also display hard ferromagnetism. This enables
us to write magnetic nanowires in CGT directly and use this method
to characterize the magnetic interaction between the interior and
edge. The results indicate that the interior saturation and depolarization
fields depend on the lateral dimensions of the sample. Most notably,
the interior region between the edges of a sample narrower than 300
nm becomes a hard ferromagnet, suggesting an enhancement of the magnetic
exchange induced by the proximity of the edges. Last, we find that
the CGT regions amorphized by the gallium beam are nonmagnetic, which
introduces a novel method to tune the local magnetic properties of
CGT films, potentially enabling integration into spintronic devices.