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Manganite bicrystal junctions in La<sub>0.7</sub>Sr<sub>0.3</sub>MnO<sub>3</sub>

Keywords:

A.M. Petrzhik – Junior Research, Kotel’nikov Institute of Radio Engineering, and Electronics Russian Academy of Sciences. E-mail: petrzhik@hitech.cplire.ru
G.A. Ovsyannikov – Dr. Sc. (Phys.-Math.), professor, the head of the laboratory, Kotel’nikov Institute of Radio Engineering, and Electronics Russian Academy of Sciences. E-mail: gena@hitech.cplire.ru


Bicrystal contacts – bridges made from epitaxial manganite film La0.67Sr0.33MnO3 grown on the bicrystal substrate (110)NdGaO3 – was investigated. Bicrystal substrate had a 12 or 38º symmetrical rotation angle around the bicrystal boundary. The angular dependence of the resonant magnetic field of the ferromagnetic resonance was mesuared in the case of rotation around films normal, external magnetic field was disposed in the film plane. This experiment allowed us to determine the misorientation angle of the magnetization axes of the two parts of the film, located on either side of the bicrystal grain boundary. The temperature dependence of the resistance, current-voltage characteristics and magnetoresistance were also mesuared. It was shown that there are two ferromagnetic ordering spin subsystems with small differing (about 1 degree) easy axis of magnetization. Magnetization axis directed along the bicrystal boundary and practically independent of bicrystal substrate disorientation. The magnetoresistance MR '= R/R750Oe increases with decreasing temperature. At T = 4,2 K, where the polarization in LSMO films is close to 100 %, MR' is 30 % for contacts with 38º substrate disorientation. With the decrease of the angle of disorientation MR' is greatly reduced, and for 12º sample MR' is close to 0,1 %. It was shown that the low MR' may be caused by the spin – polarized carriers scattering due to the strong electron – electron interaction in the grain boundary disordered layer at low temperatures and by antiferromagnetic magnons scattering at high.
References:

  1. PetrzhikA.M., OvsyannikovG.A., DemidovV.V., ShadrinA.V., BorisenkoI.V. E'lektronny'jtransportvmanganitny'xbikristallicheskixkontaktax // FTT, 2013. T. 55. Vy'p. 4. 697 s.
  2. Demidov V.V., Ovsyannikov G. A., Petrzhik A.M., Borisenko I.V., Shadrin A.V., Gunnarsson R. Magnetic anisotropy in strained manganite films and bicrystal junctions // J. Appl. Phys. 2013. V. 113. P. 163909.
  3. Gershenzon M.E., Gubankov V.N., Falej M.I. Tunnel'naya spektroskopiya e'lektron-e'lektronnogo vzaimodejstviya v neuporyadochenny'x plenkax alyuminiya // ZhE'TF 1986. T. 90. S. 2196.
  4. Dartora C.A., Gabrera G.G. Ferromagnetic tunneling junctions at low voltages: Elastic versus inelastic scattering at T=0°K // J. Appl. Phys. 2004. V. 95. R11.

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