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Zhiwei Gao

Publications and source records attributed to Zhiwei Gao.

20 records · Page 2Linked to original sources
arXiv2016

Resonant TMR inversion in LiF/EuS based spin-filter tunnel junctions

Resonant tunneling can lead to inverse tunnel magnetoresistance when impurity levels rather than direct tunneling dominate the transport process. We fabricated hybrid magnetic tunnel junctions of CoFe/LiF/EuS/Ti, with an epitaxial LiF energy barrier joined with a polycrystalline EuS spin-filter bar-rier. Due to the water solubility of LiF, the devices were fully packaged in situ. The devices showed sizeable positive TMR up to 16% at low bias voltages but clearly inverted TMR at higher bias voltages. The TMR inversion depends sensitively on the thickness of LiF, and the tendency of inversion disap-pears when LiF gets thick enough and recovers its intrinsic properties.

cond-mat.mtrl-sci↗
arXiv2016

Spin- and Symmetry-Filtering Combined Tunnel Magnetoresistance through Epitaxial MgO/EuS Tunnel Barriers

We created epitaxial magnetic tunnel junctions of FeCo/MgO/EuS on MgO buffered Si (100). Tunnel magnetoresistance reached up to 64% at 4.2 K. An unexpected fast drop of magnetoresistance was recorded for MgO thickness above 1 nm, which is attributed to the forced nonspecular conductance across the EuS conduction band minimum located at the X point, rather than the desired Delta_1 conductance centered around the Gamma point.

cond-mat.mtrl-sci↗