Condensed-Matter Physics & Materials Science Seminar

The stagnancy and obstacle of spintronics including magnetic semiconductor result from technological dilemma as well as low operation temperature for application. In this sense, it is essential to manipulate and control fundamental physical characteristics in atomic level. In ZnO based materials, the position and effect of hydrogen have been most important issue due to its contribution determining physical properties [1]. Especially in Co doped ZnO(ZnCoO), it was reported that hydrogen mediates spin state of neighbored Co ions and makes molecular magnet, Co-H-Co complex[2, 3].

In this seminar, unique characteristics and its approach for spintronic applications of hydrogen mediated ferromagnetic spin ordering will be introduced. In recent, we reported reproducible, reversible and controllable spin manipulation in ZnCoO by hydrogen mediation [3-5]. The electrical and magnetic characteristics can be controlled independently via manipulating the position of hydrogen in ZnCoO lattice through various hydrogen treatments and its condition. Using lithography techniques and subsequent hydrogen injection to localized area, the magnitude of ferromagnetism, size and even shape of magnetized area could be designed and developed arbitrary. It enables rewritable spin device, spin display device and spin logic device. These results and approach to spintronic applications will guide new direction in spin manipulation in molecular level.

[1] C. G. Van de Walle, Phys. Rev. Lett. 85, 1012 (2000); A. Janotti and Chris G Van de Walle Nat. Mater. 6, 44 (2007)
[2] C.H. Park and D. Chadi, Phys. Rev. Lett. 94, 127204 (2005),
[3] S. Lee et al., Appl. Phys. Lett. 94, 212507 (2009).
[4] Y. C. Cho et al., Appl. Phys. Lett. 95, 172504 (2009)
[5] S. J. Kim et al., Phys. Rev. B 81, 212408 (2010).