Aligned
Magnetic Domains in <i>p</i>- and <i>n</i>‑Type
Ferromagnetic Nanocrystals and in <i>pn</i>-Junction Nanodiodes
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Abstract
We form <i>pn</i>- and <i>np</i>-junctions between monolayers of <i>p</i>- and <i>n</i>-type nanocrystals that exhibit current rectification in
the nanodiodes when characterized with a scanning tunneling microscope
(STM) tip. With the use of ferromagnetic nanocrystals, we study the
effect of mutual alignment of magnetization vectors on current rectification
in the junction between the two nanocrystals. We show that when the
magnetization vectors of the <i>p</i>- and of the <i>n</i>-type nanocrystals are parallel to each other (and both
facing toward the apex of the STM tip) tunneling current in both bias
modes increases with correspondingly a higher rectification ratio.
This is in contrast to the parameters of the nanodiodes in which magnetization
vectors of the components are unaligned or randomized. To analyze
the results, we record scanning tunneling spectroscopy of the monolayer
of the components having magnetization vectors aligned or unaligned
to locate their valence and conduction band edges and to determine
the effect of the alignment on the band edges. Upon alignment of the
magnetization vectors of the nanocrystals in a monolayer, the conduction
band edge of the <i>p</i>-type and valence band edge of
the <i>n</i>-type semiconductor shift towards the Fermi
energy leading to a change in energy levels of the <i>pn</i>-junctions and accounting for the improved parameters of the nanodiodes