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TT: Fachverband Tiefe Temperaturen
TT 24: Magnetic Heuslers, Half-Metals and Oxides II (organized by MA)
TT 24.3: Vortrag
Montag, 31. März 2014, 16:00–16:15, BEY 118
NiFe2O4: a candidate for efficient spin filtering at room temperature? — •Michael Hoppe1, Sven Döring1, Mihaela Gorgoi3, Felix Gunkel4, Claus M. Schneider1,2, and Martina Müller1,2 — 1Peter-Grünberg-Institut (PGI-6), Forschungszentrum Jülich — 2Fakultät für Physik, Universität Duisburg-Essen — 3BESSY II, Helmholtz-Zentrum Berlin für Materialien und Energie — 4Peter-Grünberg-Institut (PGI-7), Forschungszentrum Jülich
For the optimized performance of spintronic devices, one major challenge is to create highly spin-polarized electron currents. One promising approach is the usage of both insulating and magnetic tunnel barriers, with a highly spin-dependent tunneling probability. For this purpose, the spinel ferrite NiFe2O4 (NFO) is a very auspicious material since it shows both features even at room temperature.
To realize magnetic tunnel junctions, it is necessary to grow NFO films (d < 5 nm) which maintain quasi bulk-like properties down to this ultrathin film limit. Therefore, NFO films with varying thickness between 2 and 20 nm are deposited on Nb-doped SrTiO3 substrates via pulsed laser deposition. HAXPES, XRD and XANES measurements reveal them to be chemically and structurally comparable to the bulk material. XMCD studies of the Ni- and Fe-L-edges in those films show that the alignment of the magnetic moments carried by these elements is preserved for all thicknesses. The insulating behavior is confirmed by CFM measurements.
On this basis, we fabricated Nb:STO/NFO/Au tunnel junctions by means of optical lithography and characterized their electrical transport properties.