10:00 〜 10:15
▼ [6a-C18-5] Transport properties of current-perpendicular-to-plane epitaxial Fe/Co-phthalocyanine/MgO/Fe junction
キーワード：phthalocyanine, Tunnel Magnetoresisance Effect, Hetero-epitaxial junction
Magnetic phthalocyanine molecules possess unquenched orbital angular momentum [1], and its radical spin may be coupled to an external electric field. Hence, phthalocyanine molecules can be important materials in the research field of spintronics. In the present study, we employed Co-phthalocyanine and characterized current-perpendicular-to-plane transport properties of Fe(001)/Co-phthalocyanine (CoPc)/MgO/Fe heteroepitaxial thin film.
The multilayer consists of MgO(001) substrate/MgO buffer(5 nm)/V(30 nm)/Fe(0.7 nm)/CoPc/MgO barrier(1.7 nm)/Fe(10 nm)/Au(5 nm), which is fabricated by molecular beam epitaxy. All of the layer were deposited at room temperature. The V layer was post-annealed at 500 °C for 30 minutes. Each growth process was monitored in-situ by reflection high energy electron diffraction. We found that MgO(001) barrier can be grown on CoPc when the CoPc thickness was less than 0.35 nm (~1 monolayer). Then the multilayer was patterned into tunnel junction, whose junction size was 2×5 μm2. In the Fe/CoPc/MgO/Fe tunnel junction, CoPc dependence of the device resistance showed a changing point at the 0.35-nm-CoPc (~1 monolayer), which strongly suggested that CoPc contributed to the electric conduction in the device. While tunnel magnetoresistance (TMR) ratio of Fe/MgO/Fe junction was 80%, relatively large TMR ratio of 20% was confirmed in Fe/CoPc/MgO/Fe tunnel junction.
[1] J. Bartolome et al., Phys. Rev. B 81 195405 (2010)
The multilayer consists of MgO(001) substrate/MgO buffer(5 nm)/V(30 nm)/Fe(0.7 nm)/CoPc/MgO barrier(1.7 nm)/Fe(10 nm)/Au(5 nm), which is fabricated by molecular beam epitaxy. All of the layer were deposited at room temperature. The V layer was post-annealed at 500 °C for 30 minutes. Each growth process was monitored in-situ by reflection high energy electron diffraction. We found that MgO(001) barrier can be grown on CoPc when the CoPc thickness was less than 0.35 nm (~1 monolayer). Then the multilayer was patterned into tunnel junction, whose junction size was 2×5 μm2. In the Fe/CoPc/MgO/Fe tunnel junction, CoPc dependence of the device resistance showed a changing point at the 0.35-nm-CoPc (~1 monolayer), which strongly suggested that CoPc contributed to the electric conduction in the device. While tunnel magnetoresistance (TMR) ratio of Fe/MgO/Fe junction was 80%, relatively large TMR ratio of 20% was confirmed in Fe/CoPc/MgO/Fe tunnel junction.
[1] J. Bartolome et al., Phys. Rev. B 81 195405 (2010)