TABLE CONTENTS Chapter 1 Introduction..............................1 1.1 Research background.............................1 1.2 Motivation......................................6 1.2.1 High-quality SrRuO3 film on SrTiO3 (001)......6 1.2.2 Sr2RuO4 film on SrTiO3 (001)..................7 Chapter 2 Instrumentation and Theories..............8 2.1 Pulse laser deposition system...................8 2.2 Structural characterization by X-ray scattering.10 2.2.1 Reciprocal space..............................10 2.2.2 X-ray diffraction.............................12 2.2.3 XRD technique for single crystal..............13 2.2.4 Scherrer’s formula...........................18 2.2.5 Strain-induced peak broadening................22 2.2.6 XRD line width analysis.......................23 Chapter 3 Experimental Procedure....................25 3.1 SrRuO3 and Sr2RuO4 deposition process in PLD....25 3.2 X-ray diffraction...............................27 3.3 X-ray photoelectron spectroscopy................27 3.4 Transport property..............................28 Chapter 4 Results and Discussion....................29 4.1 High-quality SrRuO3 film grown on SrTiO3(001) by PLD ....................................................29 4.1.1 SrRuO3 film grown by single-target PLD........29 4.1.2 SrRuO3 film grown by double-target PLD........35 4.2 Sr2RuO4 film grown by PLD.......................39 4.2.1 Sr2RuO4 film grown by single-target PLD.......40 4.2.2 Sr2RuO4 film grown by double-target PLD.......53 4.3 Comparison of single-target and double-target methods and the effect on film..............................60 Chapter 5 Conclusion................................61 Reference...........................................64 Figure captions Figure 1.1 Crystal structures of Ruddlesden-Popper (RP) ruthenates series Srn+1RunO3n+1. Both Sr2RuO4 (n = 1), Sr3Ru2O7 (n = 2), Sr4Ru3O10 (n = 3) and SrRuO3 (n = ∞)....2 Figure 1.2 Transport property of bulk SrRuO3.[4]...........2 Figure 1.3 Resistivity as a function of temperature under various magnetic fields for the Sr2RuO4 film of Tokura’s group......................................................4 Figure 1.4 XRD pattern of the Sr2RuO4 film of Tokura’s group......................................................4 Figure 1.5 Resistivity versus temperature of bulk single crystal Sr2RuO4 in the a-b-plane[9]........................5 Figure 2.1 The set-up of PLD system........................9 Figure 2.2 Combine lattice and basis to construct to a crystal...................................................10 Figure 2.3 2D real lattice and reciprocal lattice. The magnitude and direction of the vector in reciprocal lattice each represents reciprocal of the d-spacing and normal direction of planes in real space.........................11 Figure 2.4 X-ray reflected by the (hkl) planes and the derivation of Bragg’s Law................................13 Figure 2.5 Construction of four-circle diffractometer with θ, 2θ, φ and χ rotation modes.........................14 Figure 2.6 Different radial scans in reciprocal space.....16 Figure 2.7 Good quality film yields narrow width rocking curve. Bad quality film yields wide width rocking curve. (the solid lines represent x-ray that is reflected, the dashed lines represent x-ray that is not reflected.)......17 Figure 2.8 Effect of crystal size on diffraction..........19 Figure 2.9 Effect of fine crystallite size on diffraction curves....................................................21 Figure 2.10 Effect of uniform and non-uniform strains (left side of the figure) on diffraction peak position and width (right side of the figure). (a) shows the unstrained sample, (b) shows uniform strain and (c) shows non-uniform strain within the volume sampled by the x-ray beam...............22 Figure 3.1 The 3D morphology image of TiO2-terminated substrate surface by AFM. Step high of each terrace is about 0.39 nm. The each layer of r.m.s. roughness is only 0.05 nm........................................................26 Figure 3.2 The simple picture of the set-up of our PLD system....................................................26 Figure 3.3 Flowchart for the double-target growth.........27 Figure 4.1 Normal scan and rocking curve of the best sample LM122 in our previous work................................30 Figure 4.2 Normal scan of LM182, LM183, LM185 and LM186. ..........................................................32 Figure 4.3 θ-rocking curve of sample LM182, LM183, LM184 and LM186.................................................33 Figure 4.4 Resistivity as a function of temperature for LM186.....................................................34 Figure 4.5 Normal scan of the samples that the RuO2/SrRuO3 laser pulse ratio was varied from 1:5 to 4:5..............36 Figure 4.6 θ-rocking curve of the samples that the RuO2/SrRuO3 laser pulse ratio was varied from 1:5 to 4:5. ..........................................................37 Figure 4.7 The relationship between room temperature resistivity and c-axis parameter of co-deposited SrRuO3 thin films.....................................................38 Figure 4.8 Resistivity versus temperature plot for the samples deposited by double-target growth.................38 Figure 4.9 Normal scan of LM205 plotted with logarithmic scale.....................................................40 Figure 4.10 JCPDS card for Sr3Ru2O7.......................41 Figure 4.11 Long-range normal scans plotted with logarithmic scale for the samples grown by single-target deposition. ..........................................................45 Figure 4.12 The detailed view of (006) peak of Sr2RuO4 in the samples grown by single-target deposition.............46 Figure 4.13 Long-range normal scans plotted with logarithmic scale for the samples grown by single-target deposition. ..........................................................49 Figure 4.14 Transport property of LM223, LM226 and LM232S.49 Figure 4.15 Long-range normal scans plotted with logarithmic scale for the samples grown by single-target deposition...50 Figure 4.16 Transport property of LM231 and LM225.........50 Figure 4.17 Transport property of LM232S and LM232L.......52 Figure 4.18 H-L mesh scan below (a) SrTiO3 (202) in LM232S and (b) LSAT (202) in LM232L..............................52 Figure 4.19 Long-range normal scans plotted with logarithmic scale for the samples grown by double-target deposition...54 Figure 4.20 The detailed view of (006) peak of Sr2RuO4 in the samples grown by double-target deposition.............55 Figure 4.21 Long-range normal scan plotted with logarithmic scale for LM229...........................................56 Figure 4.22 θ-rocking curves for SrTiO3 substrate and Sr2RuO4 film..............................................56 Figure 4.23 H-L mesh scan below SrTiO3 (202) in LM229.....57 Figure 4.24 Azimuthal scans for SrTiO3{202} and Sr2RuO4{206} reflections...............................................58 Figure 4.25 Transport property of LM229...................58 Figure 4.26 Transport property of the thicker Sr2RuO4 films grown on SrTiO3 and LSAT..................................59 Table captions Table 4.1 The growth conditions of sample LM122, LM182, LM183, LM185 and LM186....................................33 Table 4.2 The thickness, c-axis parameter, room temperature resistivity and width of rocking curve of the samples.....34 Table 4.3 The thickness, c-axis parameter, room temperature resistivity and width of rocking curve of the samples.....37 Table 4.4 The transformation from two-theta to L..........41 Table 4.5 The growth conditions of the samples grown by single-target deposition..................................44 Table 4.6 Growth conditions of the samples grown by single-target deposition. (The thickness of LM223, LM226 and LM225 was estimated by thickness fringe and the thickness of LM232 and LM231 was estimated by growth rate )..................48 Table 4.7 The growth conditions of LM210, LM213, LM215 and LM219.....................................................54