Subject: [Depfis] miercoles 8 Seminario de Materia Condensada

From: Daniel Gomez <[email-masked]>
Date: Tue, 7 Mar 2006 14:31:20 -0300 (ART)

Miercoles 8 de marzo, 14hs, aula Federman

Seminario de Materia Condensada

Dr. Takeshi Fujii

AIST - Tsukuba, Japon

" The Colossal Electro-Resistance effect in SrRuO3/Nb doped SrTiO3 
junctions."

Recently, electric field and/or current induced resistance switching at room 
temperature, i.e. colossal electo-resistance (CER), has been reported in 
perovskite oxides such as Cr-doped SrZrO3, SrTiO3 [1] and Pr0.7Ca0.3MnO3[2] 
sandwiched between metal electrodes.  This behavior attracts a great 
interest for its possible device application as nonvolatile memory. However, 
the mechanism of the resistance switching is still an open question.

In the present study, we have investigated the CER effect and transport 
properties for heteroepitaxial perovskite oxide junctions consisting of 
SrRuO3 (SRO) deposited on (001) SrTi0.99Nb0.01O3(Nb:STO) single crystal 
substrates. The SRO/Nb:STO interface exhibits rectifying Schottky-like I-V 
characteristics with large hysteresis and the resistance can be switched by 
applying pulsed-voltage stresses. Moreover, insertion of different 
perovskite oxides between the SRO/Nb:STO interface can modify the switching 
behavior of the junction, indicating that the CER effect takes place at the 
interface. On the basis of the experimental results, we propose that the CER 
effect is caused by the change of interface resistance, i.e. an alternation 
of a Schottky-like barrier hight due to a charge trapping effect at the 
interface stats. [3]

[1] A. Beck et al., Appi. Phys. Lett 77, 139 (2000); Y. Watanabe et al., 
Appi. Phys. Lett. 78, 3738 (2001).

[2] S. Q. Liu et al., Appi. Phys. Lett 76, 2749 (2000)

[3] T. Fujii et al., Appi. Phys. Lett 86, 012107 (2005)