Current dependence of the magnetoresistance in a colloidal-sphere-masked ion-milled thin filmJ. Li1, 2, D. N. Zheng1, X. S. Rao3, C. H. Sow2, L. Chen1 and C. K. Ong2
1 National Laboratory for Superconductivity, Institute of Physics Chinese Academy of Sciences - Beijing 100080, PRC
2 Centre for Superconducting and Magnetic Materials (CSMM) and Department of Physics, National University of Singapore 2 Science Drive 3, Singapore 117542
3 Temasek Laboratories, National University of Singapore Engineering Drive 3, Singapore 119260
(Received 11 August 2003; accepted in final form 8 January 2004)
An epitaxial thin film covered with a monolayer of colloidal spheres was ion-milled so that structural discontinuities were involved. Nonlinear V- I characteristics have been observed, revealing that the zero-field resistance of the sample decreases with increasing measuring current I. In a magnetic field, however, the resistance varies non-monotonically with I. An inflexion appears around I=50 . Accordingly, the magnetoresistance also correlates with I. A maximum value as high as ( ) is recorded at liquid nitrogen in 1.5 when I=1 . The drastic current dependence of the magnetoresistance is believed to come from the ion-milling-induced structural and magnetic disorders and to be related to the inelastic scattering of the spin-polarized electrons at the disorders. The possible underlying mechanisms are discussed in detail.
75.47.Gk - Colossal magnetoresistance.
75.47.Lx - Manganites.
72.25.Dc - Spin polarized transport in semiconductors.
© EDP Sciences 2004