| Bio | 
| Paper |
Joseph Kassim
Saint Cloud State University
Subject Listing - Physics/Astronomy
Advisor: Dr. Rajeswari M. Kolagani
Saturday, Poster Session 6, Presentation Kiosk 18 C, Health & Fitness Center
THICKNESS DEPENDENT TRANSPORT PROPERTIES OF MANGANITE THIN FILMS
The purpose of this research was to study the effect of substrate-induced lattice mismatch strain on the transport properties of thin films of colossal magnetoresistive (CMR) materials. There has been significant research interest in the CMR materials recently due to their potential for technological applications in magnetic information storage and infrared detector technology. Understanding and controlling the behavior of thin films is important for realizing these applications. We have therefore studied the influence of the substrate-induced lattice mismatch strain on the colossal magnetoresistive material La 0.67 Ca 0.33 MnO 3 (LCMO) films grown on two substrates, LaAlO3 and NdCaAlO4 . The lattice constants of these substrates are significantly smaller than that of LCMO thus introducing compressive in-plane lattice mismatch strain in the thin films. The films were grown using the Pulsed Laser Deposition technique and were of the thickness ranging between 45nm to 610nm. Deposition conditions were optimized to achieve the optimal target cation oxygen stoichiometry as well as good crystalline quality. Film thickness was measured using a Dektak profilometer. Electrical resistivity measurements were done using the standard 4-point contact method in the Vander Pauw geometry. Structural analysis of the films was done using a 4-circle x-ray diffractometer. Experimental data show that LCMO grown on a closely lattice- matched substrate show no pronounced thickness dependence of resistivity; in other words, the 45nm film has properties very similar to the 610nm film. However, analysis of the data on the two lattice-mismatched substrates shows that there is pronounced thickness thickness dependence of the electrical properties associated with the presence of lattice mismatch strains. The lattice mismatch strain depends on the crystal structure of the substrate and film thickness. The choice of optimal values of these parameters is crucial for designing these materials for technological applications
Advisor: Dr. Rajeswari M. Kolagani, Assistant Professor, Physics, Astronomy, and Geosciences, Towson University, Towson, MD