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MA: Fachverband Magnetismus

MA 28: Spin-dependent Transport Phenomena

MA 28.4: Vortrag

Donnerstag, 25. März 2010, 16:00–16:15, H3

Inelastic Electron Tunneling Spectroscopy of CoFeB/ MgO/ CoFeB based magnetic tunnel junctions in high magnetic fields — •Marvin Walter¹, Vladyslav Zbarskyy¹, Markus Münzenberg¹, Michael Seibt², Volker Drewello³, Markus Schäfers³, Günter Reiss³, and Andy Thomas³ — ¹I. Phys. Inst., Georg-August-Universität Göttingen, 37077 Göttingen — ²IV. Phys. Inst., Georg-August-Universität Göttingen, 37077 Göttingen — ³Bielefeld University, Physics Department, 33501 Bielefeld

Magnetic tunnel junctions (MTJs) showing a high tunnel magnetoresistance (TMR) are important for the fabrication of MRAM devices when combined with current induced switching.

We discuss inelastic electron tunneling spectroscopy (IETS) measurements on CoFeB/MgO/CoFeB magnetic tunnel junctions. The junctions are prepared by means of magnetron sputtering of CoFeB and e-beam evaporation of stoichiometric MgO. Structuring of the multilayer is done using a photolithography process and Argon ion-milling.

The IETS measurements are carried out at low temperatures down to 4.2 K, high magnetic fields up to 9 T and in parallel as well as antiparallel electrode configuration in order to distinguish between different kind of excitations such as e.g. magnons and phonons. Furthermore, oxygen vacancies in the MgO barrier are controlled through variation of the sample temperature during e-beam growth to investigate the influences of these vacancies on the tunneling spectra of MTJs. Research is supported by DFG SFB 602.