Dresden 2006 – wissenschaftliches Programm
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MA: Magnetismus
MA 20: Poster: Films(1-36) Transp(37-56) Ex.Bias(57-67) Spindyn(68-80) Micromag(81-95) Particle(96-109) Imag.+Surface(110-113) Spinelectr(114-122) Theory+Micromag(123-131) Spinstr+Aniso(132-142) MagMat(143-156) Meas(157,158) MolMag+Kondo(159-162) Postdead(163-)
MA 20.121: Poster
Dienstag, 28. März 2006, 15:15–19:15, P1
Fully epitaxial TMR stacks based on NiMnSb — •F. Lochner, P. Bach, C. Gould, G. Schmidt, and L. W. Molenkamp — Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
Fully epitaxial TMR stacks have been a challenge since a long time. Epitaxial growth of a tunnel barrier on a magnetic metal and vice versa are still a problem. We have grown stacks suitable for TMR geometries based on NiMnSb as a ferromagnet and II-VI semiconductor barriers. The samples we use consist of a sulfur doped InP substrate with a 100-200nm thick (In, Ga)As buffer (lattice matched to the substrate) [1] and the TMR structure. This TMR structure has a layer sequence of NiMnSb, tunnel barrier, NiMnSb. The NiMnSb alloy crystallizes in the C1b structure [2] which is compatible to existing semiconductor technology. It has a high Curie temperature of 730K and a very high spin polarization (up to 100 % at the Fermi level). The TMR stack itself consists of two NiMnSb layers between which a II-VI semiconductor barrier is sandwiched. For the barrier ZnTe as well as ternary compounds like Zn(Se,Te) or ZnSe/ZnTe superlattices have been used. We acknowledge the support of BMBF grant 13N8284.
[1] P. Bach, C. Rüster, C. Gould, C. R. Becker, G. Schmidt, L. W. Molenkamp, Journal of Crystal Growth 251 (2003) 323-326
[2] R.A. de Groot, F.M. Mueller, P.G. van Engen, K.H.J. Buschow, Phys. Rev. Lett. 50 (1983) 2024