Interface structure and transport of complex oxide junctions

The interface structure and magnetism of hybrid magnetic tunnel junction-spin filter devices have been investigated and correlated with their transport properties. Magnetic tunnel junctions made of a spinel NiMn2O4 tunnel barrier sandwiched by theoretically predicted half-metallic electrodes, perovskite La0.7Sr0.3MnO3 and spinel Fe3O4, exhibit very high crystalline quality as observed by transmission electron microscopy. Structurally abrupt interfaces allow for the distinct magnetic switching of the electrodes as well as large junction magnetoresistance. The change in the magnetic anisotropy observed at the spinel-spinel interface is indicative of a thin interdiffused magnetically soft interfacial layer. The strong exchange coupling at this interface allows for low background magnetoresistance, and a spin-filter effect with when the barrier is ferrimagnetic.

[1]  V. Laukhin,et al.  Elastic and orbital effects on thickness-dependent properties of manganite thin films , 2007, 0708.3602.

[2]  R. Chopdekar,et al.  Probing the role of the barrier layer in magnetic tunnel junction transport , 2007, 0706.2726.

[3]  R. Chopdekar,et al.  Spin-polarized conduction in oxide magnetic tunnel junctions with magnetic and nonmagnetic insulating barrier layers , 2006 .

[4]  G. T. Woods,et al.  Analysis of point-contact Andreev reflection spectra in spin polarization measurements , 2003, cond-mat/0307693.

[5]  G. Hu,et al.  Negative spin polarization of Fe3O4 in magnetite/manganite-based junctions. , 2002, Physical review letters.

[6]  H. Padmore,et al.  First commissioning results for the elliptically polarizing undulator beamline at the Advanced Light Source , 2001 .

[7]  T. Schulthess,et al.  Spin-dependent tunneling conductance of Fe | MgO | Fe sandwiches , 2001 .

[8]  David J. Singh,et al.  Transport and fermiology of the ferromagnetic phase of (A = Ca, Sr, Ba) , 1997 .

[9]  Suzuki,et al.  Exchange coupling in single-crystalline spinel-structure (Mn,Zn)Fe2O4/CoFe2O4 bilayers. , 1996, Physical review. B, Condensed matter.

[10]  J. Moodera,et al.  Large magnetoresistance at room temperature in ferromagnetic thin film tunnel junctions. , 1995, Physical review letters.

[11]  Zhang,et al.  Electron states, magnetism, and the Verwey transition in magnetite. , 1991, Physical review. B, Condensed matter.

[12]  Akira Yanase,et al.  Band Structure in the High Temperature Phase of Fe3O4 , 1984 .

[13]  M. Julliere.  Tunneling between ferromagnetic films , 1975 .

[14]  S. Pollack,et al.  Magnetic Spectra of Manganese Ferrites , 1958 .