Technical Reports

Spin-dependent tunnelling junctions with amorphous CoNbHfFe

Sharma, Manish; Tran, Lung T.; Anthony, Thomas C.; Warot, Benedicte; Petford-Long, Amanda K.

HPL-2002-189

Keyword(s): No keywords available.

Abstract: We report on using amorphous Co₇₇Nb₁₆Hf₆Fe_1` (CoNbHfFe) as the ferromagnetic electrode in bottom-pinned magnetic tunnel junctions (MTJ's). Exchange bias with CoNbHfFe was achieved with Mn₇₅Ir₂₅ as the antiferromagnetic pinning layer. In a first sample with both pinned and sense layers being CoNbHfFe, a tunnelling magnetoresistance ratio (TMR) of 5% was found. In comparison, a TMR of 16.4% was found in a second sample with a pinned Co₅₀Fe₅₀ electrode and a sense CoNbHfFe electrode. This leads to a low spin-polarization of about 15% for CoNbHfFe at room temperature. High- resolution transmission electron microscopy (HREM) images show that while the first sample has a fully amorphous sense layer, the sense layer in the second sample is largely amorphous with nano-crystalline inclusions. Both pinned layers are found to be highly textured and crystalline. To study switching distributions, large MTJ arrays were patterned using electron-beam lithography and the magneto-optic kerr effect (MOKE) was used to measure the switching of the sense layer. MOKE results for the two samples are compared in arrays with devices of different sizes.

11 Pages

Back to Index

»Technical Reports

Heritage Technical Reports