  Nanoscale magnetic junction provides a useful approach to act as the building
block for magnetoresistive random access memories (MRAM), where one of the key
issues is to control the magnetic domain configuration. Here, we study the
domain structure and the magnetic switching in the Permalloy (Fe20Ni80)
nanoscale magnetic junctions with different thicknesses by using micromagnetic
simulations. It is found that both the 90-degree and 45-degree domain walls can
be formed between the junctions and the wire arms depending on the thickness of
the device. The magnetic switching fields show distinct thickness dependencies
with a broad peak varying from 7 nm to 22 nm depending on the junction sizes,
and the large magnetic switching fields favor the stability of the MRAM
operation.
