Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 75: Transport: Spintronics and magnetotransport 1 (TT, jointly with HL, MA)

HL 75.7: Talk

Thursday, March 14, 2013, 11:00–11:15, H18

First-principles calculation of ballistic transport in single-atom contacts — •Fabian Otte¹, Björn Hardrat¹, Frank Freimuth², Yuriy Mokrousov² und Stefan Heinze¹ — ¹Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany — ²Peter-Grünberg-Institut, Forschungszentrum Jülich, 520425 Jülich, Germany

Recently, the spin-valve effect of single-atom contacts has been demonstrated using scanning tunneling microscopy [1]. In these measurements a magnetic tip approaches magnetic adatoms on a surface and the distance-dependent conductance and magnetoresistance is obtained. Here, we report first-principles calculations of ballistic transport in model systems of such single-atom contacts using our recently developed approach [2] which allows to include spin-orbit coupling and non-collinear spin structures. We present the conductance between two ferromagnetic Co monowires terminated by single Mn apex atoms while varying the distance between the two Mn atoms. Due to frustration of exchange interactions a non-collinear spin state is favorable in the contact regime. We show that it leaves a fingerprint in the distance-dependent conductance and magnetoresistance [3]. We also study the ballistic anisotropic magnetoresistance from the tunneling to the contact regime for leads whose structure is modeled with Fe monowires.
[1] M. Ziegler et al., New J. Phys. 13, 085011 (2011)
B. Hardrat et al., Phys. Rev. B 85, 245412 (2012)
B. Hardrat et al., Phys. Rev. B 86, 165449 (2012)