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MA: Fachverband Magnetismus
MA 44: Surface Magnetism (Joint Session with O) - Adatoms on surfaces
MA 44.7: Talk
Thursday, March 19, 2015, 16:45–17:00, H 0110
Unexpected antiferromagnetic coupling of Cr-porphyrin to bare cobalt thin film — •Jan Girovsky1, Kartick Tarafder2,3, Jan Nowakowski1, Christian Wäckerlin4, Milos Baljozovic1, Dorota Siewert5, Aneliia Wäckerlin5, Armin Kleibert6, Nirmalya Ballav7, Thomas A. Jung1, and Peter M. Oppeneer2 — 1LMN, PSI, Villigen, Switzerland — 2Uppsala University, Uppsala, Sweden — 3BITS, Shameerpet, Andhra Pradesh, India — 4LNS, EPFL, Lausanne, Switzerland — 5University of Basel, Basel, Switzerland — 6SLS, PSI,Villigen, Switzerland — 7IISER, Pune, India
Spin bearing square-planar metallo-organic complexes interact magnetically with ferromagnetic (FM) substrates even up to room temperature[1]. So far, exclusively FM ordering has been reported for such molecules adsorbed on bare metallic ferromagnets [2,3]. Here, we present a combined experimental and theoretical study on CrTPP molecules antiferromagnetically (AFM) coupled to bare cobalt substrate. The observed AFM interaction is confirmed by DFT+U calculations and alternatively described within the framework of Goodenough-Kanamori-Anderson (GKA) rules. In the GKA model, the less than half-filled 3d shell of the Chromium ion interacts with the out-of-plane orbitals of the cobalt atoms via indirect 90 degree exchange coupling mediated by the porphyrins’ nitrogen atoms[4].
[1] A. Scheybal et al, Chem Phys Lett 411, 214 (2005).
[2] N. Ballav et al, JPCL 4, 2303 (2013).
[3] A. Lodi Rizzini et al, Surface Science 630, 361 (2014).
[4] J. Girovsky et al, PRB (R), in press