Optimization of nano-oxide Layer in CIP spin valves

The influence of nano-oxide layer (NOL) on interlayer coupling (Hin) and magnetoresistance (MR) of bottom spin-valves (SV) were studied by inserting NOL at four positions: 1) before the Cu spacer; 2) in the middle of the Cu spacer; 3) after the Cu spacer; and 4) after the Cu cap layer. The NOL smoothens the surface of the interface at position 1), 3), and 4), except for 2). Surface flatten by NOL is associated with CoFeOx. Ten percent of MR enhancement can be achieved with NOL at the position 3) and 4). Weak antiferromagnetic interlayer coupling was observed with NOL at position 3). A 27.2% MR ratio has been reached in dual spin valve with two NOLs in two pinned layers.