Ion implantation induced enhancement of magnetoresistance in La0.67Ca0.33MnO3

Abstract

Thin films of colossal magnetoresistance (MR) material, La0.67Ca0.33MnO3, were implanted with different doses (1011–1015 ions/cm2) of 200 keV Ar+ ions. The implanted samples were examined by ion channeling and x-ray diffraction techniques. The channeling results clearly showed that the magnitude of the induced lattice disorder did not increase greatly for implantation doses up to 5×1013 ions/cm2. In this low dose implantation regime, the magnetoresistance {MR=[R(0)−R(H)]/R(0)} increased by 50%, the peak resistivity went up by two orders of magnitude, and the magnetoresistivity peak temperature decreased by 130 K compared to the original, unimplanted sample. For doses ≥5×1013 ions/cm2, the damage was significant and caused the sample to become semiconducting.

Reentrant metal–insulator-type transition induced by high fluence chromium ion implantation of La0.7Ca0.3MnO3 thin films

“…The 10 13 ions/cm 2 implantation qualitatively reproduced that shown in Ref. 9. Of specific interest in this study was the observation that increasing the fluence further to 5 ϫ10 15 ions/cm 2 causes a peak in the resistance to reappear within our measurement window.…”

“…Chen et al 9 implanted 200 keV Ar ϩ ions at fluence between 10 11 and 10 15 ions/cm 2 and found that the major influence of the implantation was to increase peak resistivity, and magnetoresistance, and decrease magnetoresitivity peak temperature. A detailed mechanism for these effects was not presented.…”

“…This behavior is consistent with the previously reported Ar ϩ implantation study, which also found that the ion induced damage could be annealed by hightemperature treatment. 9 Although we have no direct evidence that Cr has substituted onto the Mn site, it is interesting to review work where this has been studied. The magnetic properties of the LaMn 1Ϫx Cr x O 3 system were studied by Jonker 12 was positive, i.e., ferromagnetic.…”

Ion beam induced surface and interface engineering

“…[25,26]. It is found that low energy (keV) ion implantation causes significant changes in the transport behaviour of manganites but since the ion remains in the film it has non-uniform depth profile in the film [27,28]. High energy oxygen ion irradiation of epitaxial LCMO thin film has been used to study the structural magnetization and magnetotransport properties.…”

Influence of high-energy electron irradiation on the transport properties of La Ca MnO films ( )

“…Since it is assumed 38 in the general case that the hopping distance a h is equal to a lattice constant, the noninteracting limit is quite justified for these doped manganites. For the value of dpa in this study (about In ion-irradiation experiments [16][17][18][19] much larger dpa values (up to 0.01 and more) have been produced which have resulted in an increase in resistance in the insulating paramagnetic state by one (and sometimes two) order of magnitude. This effect is accompanied by an increase in the activation energy E a (see Eq.…”