B. C. Lee

Effect of oxidizing the ferromagnetic electrode in magnetic tunnel junctions on tunneling magnetoresistance

The ferromagnetic layer in magnetic tunnel junctions (MTJs) was oxidized with varying O2 concentrations, and the corresponding effect on spin-dependent transport was studied. As expected from our previous results for MTJs with an over-oxidized AlOx tunnel barrier, a partially oxidized ferromagnetic layer plays an important role in spin-dependent transport. As the temperature is lowered, the junction resistance increases dramatically, and the tunneling magnetoresistance (TMR) is strongly suppressed. Increasing the O2 concentration enhances the increase of resistance and suppression of TMR. This work supports our previous conclusion that oxidizing the ferromagnetic layer generates localized magnetic moments, which act as a scattering center for spin-polarized tunneling electrons.

Large spin susceptibility of HgCdTe two dimensional electron gas in the extreme quantum limit regime

The spin susceptibility of HgCdTe 2DEG system was measured in this study with two independent methods which yielded the same value. It is remarkably large compared to any other 2DEG system. The large value of spin susceptibility as well as the large g-factor are the unique properties of HgCdTe which can be utilized as spintronic material.

Nonlocal Spin Transport in Lateral Spin Valves with Multiple Ferromagnetic Electrodes

We study the nonlocal spin transport in a lateral spin valve with multiple ferromagnetic (FM) electrodes. When two current-injecting and two spin current-detecting electrodes are all ferromagnetic, the number of possible nonlocal spin signal states is four at maximum. In reality, this number is reduced, depending on the inter-probe distance and the relative magnitudes of the spin resistances. Our theoretical results are in agreement with recent experiments of spin injection into an Al island, a carbon nanotube, and graphene.