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First-principles calculations of the atomic and electronic structure of crystalline CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) are performed to understand the effect of B on spin-dependent transport in these junctions. The authors find that it is energetically favorable for B atoms to reside at the crystalline CoFeB/MgO interface rather than remain in the bulk of the crystalline CoFeB electrode. The presence of B at the interfaces is detrimental to tunneling magnetoresistance (TMR) because it significantly suppresses the majority-channel conductance through states of Δ1 symmetry. Preventing B segregation to the interfaces during annealing should result in an enhanced TMR in CoFeB/MgO/CoFeB MTJs. [ABSTRACT FROM AUTHOR]

The electrical resistance of a constrained domain wall in a nanojunction is investigated using micromagnetic modeling and ballistic conductance calculations. The nanojunction represents two ferromagnetic electrodes connected by a ferromagnetic wire of 10 nm in length and of a few nanometers in cross section. We find that the anisotropy of the electrodes favors a localization of the domain wall within the constriction (wire) revealing a positive domain-wall resistance. An applied magnetic field moves the domain wall toward one of the electrodes and reduces its width. This compression of the domain wall leads to a sizeable enhancement of the domain-wall resistance. [ABSTRACT FROM AUTHOR]