We first study noninteracting electrons moving on corner-sharing tetrahedral lattices, which represent the conduction path of LiAlyTi2−yO4. A uniform box distribution type of disorder for the on-site energies is assumed. Using the Dyson-Mehta Delta-3 statistics as a criterion for localization, we have determined the critical disorder (Wc/t = 14.5 ± 0.25) and the mobility-edge trajectories. Then we study the Anderson-Hubbard model, which includes both interactions and disorder, using a real-space self-consistent Hartree-Fock theory. We provide a partial assessment on how the Hartree-Fock theory approximates the ground states of the Anderson-Hubbard model, using small clusters which can be solved exactly. The Hartree-Fock theory works very well in reproducing the ground-state energies and local charge densities. However, it does not work as well in representing the spin-spin correlations. To find the ground state, one needs to allow maximum degree of freedom in spins. Evidence of screening of disorder by the interactions is provided. We have applied the Hartree-Fock theory to large-scale three-dimensional simple cubic lattices. For a disorder strength of W/t = 6, weak interactions (U/t ≤ 3) enhance the density of states at the Fermi level and the low-frequency conductivity. There are no local magnetic moments, and the AC conductivity is Drude-like. With stronger interactions (U/t ≥ 4), the density of states at the Fermi level and the low-frequency conductivity are both suppressed. These are accompanied by the presence of local magnetic moments, and the conductivity becomes non-Drude-like. A metal-to-insulator transition is likely to take place at a critical Uc/t ≈ 8 – 9. We find that (i) the formation of magnetic moments is essential to the suppression of the density of states at the Fermi level, and therefore essential to the metal-insulator transition; (ii) the form of magnetic moments does not matter; and (iii) these results do not depend on the type of lattice or the type of disorder. / Thesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2009-05-26 02:20:04.652

In this dissertation, we study properties of quantum interaction phenomena in two-dimensional (2D) and one-dimensional (1D) electronic systems in p-GaAs micro- and nano-scale devices. We present low-temperature magneto-transport data from three forms of low-dimensional systems 1) 2D hole systems: in order to study interaction contributions to the metallic behavior of 2D systems 2) Bilayer hole systems: in order to study the many body, bilayer quantum Hall state at nu = 1 3) 1D hole systems: for the study of the anomalous conductance plateau G = 0.7 ???? 2e2/h The work is divided into five experimental studies aimed at either directly exploring the properties of the above three interaction phenomena or the development of novel device structures that exploit the strong particle-particle interactions found in p-GaAs for the study of many body phenomena. Firstly, we demonstrate a novel semiconductor-insulator-semiconductor field effect transistor (SISFET), designed specifically to induced 2D hole systems at a ????normal???? AlGaAs-on-GaAs heterojunction. The novel SISFETs feature in our studies of the metallic behavior in 2D systems in which we examine temperature corrections to ????xx(T) and ????xy(T) in short- and long-range disorder potentials. Next, we shift focus to bilayer hole systems and the many body quantum Hall states that form a nu = 1 in the presence of strong interlayer interactions. We explore the evolution of this quantum Hall state as the relative densities in the layers is imbalanced while the total density is kept constant. Finally, we demonstrate a novel p-type quantum point contact device that produce the most stable and robust current quantization in a p-type 1D systems to date, allowing us to observed for the first time the 0.7 structure in a p-type device.

The physics of two-phase systems is explored here, particularly magneto-transport and low temperature d.c. conductivity in thin films. The extraordinary magnetoresistance (EMR) effect was analysed in the context of previous experimental and theoretical considerations. The magnetoresistance (MR) may be enhanced by up to two orders of magnitude by changing the geometry. This was investigated using finite element analysis. Thin film samples consisting of a layered structure of Germanium-Tin-Germanium (Ge-Sn-Ge) were created in collaboration with Shandong University in China. Ge layers were kept at a constant thickness across all samples, with variable Sn thickness. Regions of Sn form island-like shapes ten times larger than the average film thickness, as is seen in scanning electron microscope (SEM) images. Raman spectroscopy was conducted on these samples, from which it is concluded that the Ge layers are amorphous in nature. It was seen that there is a relationship between the electrical resistance and the film thickness which is indicative of a metal-insulator transition (MIT). The temperature dependence of resistivity was subsequently investigated. The temperature coefficient of resistivity (TCR) of the samples is seen to become negative as the thickness of the Sn layer is reduced below a certain critical thickness. Depending on their thickness, samples were designated as metallic or insulator, and various models associated with metals and insulators fitted to the data. While it is impossible to be absolutely certain of the validity of each of the models, some are a better fit than others. The same temperature dependence of resistivity was measured with an applied magnetic field. This is compared with the previous EMR investigation, however the MR of the samples is only of the order of a few percent which corresponds to ordinary MR, seen in most metals. The magnetic field measurements suppress a resistivity down-turn at very low temperatures (T < 10K) which suggests the presence of superconductivity. Analysis of dr=dT shows that the onset of superconductivity is lower for samples with a lower Sn thickness. Additionally, the deposition rate of the Sn layer affects the resistivity significantly; a higher deposition rate causes a decrease in resistivity. It is supposed that this is due to a change in the microstructure of the film. Finally, piezo-resistivity was considered by applying mechanical compression to the samples. The added pressure causes a drop in resistivity.

Esta tese apresenta um estudo sistemático da síntese e das propriedades físicas de amostras policristalinas de Nd IND. 1-X R IND. X NiO IND. 3; R = Sm, Eu, 0 < OU = X < OU = 1. Estes materiais apresentam uma transição de fase metal-isolante MI em temperaturas 200 < OU = T IND. MI < OU = 400 K. Amostras foram produzidas a partir do método de precursores sol-gel, sinterizadas a 1000 GRAUSC e sob pressões de O IND. 2 de até 80 bar. O estudo da influência da substituição de R POT. 3+ na matriz de NdNiO IND. 3 foi realizado a partir das caracterizações através de medidas de difração de raios-X DRX, difração de neutrons como função da temperatura DRN, transporte elétrico ro(T), transporte térmico capa(T), coeficiente Seebeck S(T), calorimetria diferencial e susceptibilidade magnética qui(T). Os resultados de DRX revelaram que as amostras são monofásicas e cristalizam-se na estrutura perivskita distorcida ortorrombicamente, grupo espacial Pbnm. As medidas de DRN realizadas nas amostras de Nd IND. 1-XEu IND. X NiO IND. 3 mostraram a evolução dos parâmetros de rede e do volume da cela unitária V como função da temperatura. Estas caracterizações revelaram que, em T DA ORDEM DE T IND. MI, ocorre uma expansão em V, assim como um aumento do ângulo de ligação Ni-O e uma diminuição do ângulo de \"superexchange\" teta. Medidas de ro(T) revelam a ocorrência da transição MI em um amplo intervalo de temperatura 200 < OU = T IND. MI 400 K. Através destas medidas verificou-se também a presença de histerese térmica ocorre decresce continuamente com o aumento de x, até anular-se em x > 0,5 e em x > 0,35 para R=Sm e Eu, respectivamente. Este resultado foi confirmado através das medidas de capa(T) e S(T). Além disso, verificou-se a importância da contribuição da rede na capa(T). As medidas de S(T) indicam que os portadores de carga são elétrons e que a densidade de ) estados no nível de Fermi N(E IND. F) foi estimada ser da ordem de 10 POT. 23 (eVcm POT. 3) POT. -1. Os valores de T IND. MI e a presença ou não de histerese térmica foram verificados através das medidas de DSC. Um estudo foi feito para verificar qual a maneira mais precisa de subtrair a contribuição dos íons terras-raras nas medidas de susceptibilidade magnética qui(T) dos compostos Nd IND. 1-X R IND. X NiO IND. 3. Após estas correções foi possível verificar o ordenamento magnético da sub-rede do Ni POT. 3+ na região de temperatura T IND. n DA ORDEM DE 200 K para as amostras com x < 0,4 e x < 0,25 para R=Sm e Eu, respectivamente. Ajustes lineares feitos em qui(T) acima de temperaturas T > 200 K revelaram valores de momentos magnéticos efetivos müeff variando de 1,7 a 1,8 mü IND. B o que está em concordância com o valor esperado de müeff DA ORDEM DE 1,76 mü IND. B do íon livre de Ni POT. 3+. Adicionalmente, uma separação precisa do termo independente da susceptibilidade magnética foi efetuada e a susceptibilidade de Pauli dos materiais foi encontrada. Foi possível então obter uma estimativa da densidade de estados no nível de Fermi N(E IND. F), que gerou valores similares aos obtidos via medidas do coeficiente Seebeck. Entretanto, o comportamento de qui(T) corrigido abaixo de T IND. n revelou características de um antiferromagnetismo não convencional devido a um aumento monotônico de qui(T) com o decréscimo da temperatura e a presença de irreversibilidade nas curvas resfriadas a campo magnético zero ZFC e do refinamento de estrutura estimou-se que a valência no Ni nas amostras de Nd IND. 1-X R IND. X NiO IND. 3 DA ORDEM DE 3. Estimativas grosseiras da largura de bando W do O 2ro e da energia de transferência de carga delta para a série de compostos Nd IND. 1-X R IND. X NiO IND. 3 revelaram valores compatíveis com aqueles ) encontrados na literatura. De maneira geral, as caracterizações das propriedades estruturais, de transporte e magnéticas sugerem que os compostos Nd IND. 1-X R IND. X NiO IND. 3 podem ser classificados como sistemas onde correlações eletrônicas e flutuações dessas correlações ocorrem. Foram discutidas algumas limitações acerca da aplicabilidade dos modelos vigentes para a explicação da transição metal-isolante nos niquelatos aqui estudados. / This work reports a systematic study on the synthesis and general physical properties of polycrystalline samples of Nd IND. 1-X R IND. X NiO IND. 3; R = Sm, Eu, 0 < OU = X < OU = 1. These compounds exhibit a metal-insulator MI phase transition in a broad range of temperature 200 < OU = T IND. MI < OU = 400 K. The samples were prepared through sol-gel precursors and sintered at extreme conditions: high temperatures 1000 GRAUSC and under oxygen pressures up to 80 bar. These samples were characterized by several techniques including X-ray powder diffraction XRD, neutron diffraction as a function of temperature NRD, electrical resistivity ro(T), thermal conductivity capa(T), Seebeck coefficient S(T), differential scanning calorimetry DSC, and magnetic susceptibility qui(T). The results of XRD revealed that all samples are single phase and crystallize in an orthorhombic structure, space group Pbnm. The NRD data, combined with the Rietveld analysis, indicated small changes in the lattice parameters a, b, and c and in the volume V of the unit cell T DA ORDEM DE T IND. MI. Such a small change in these parameters is accompained by either a little decrease of the superexchange angle teta and a small expansion of the Ni-O bond-length. The ro(T) data exhibit interesting features such as: (1) a metallic-like behavior of ro(T) at high temperatures; (2) a huge increase of the magnitude of ro(T) at T DA ORDEM DE T IND. MI; and (3) a thermal hysteresis occurring just below T DA ORDEM DE T IND. MI in a temperature interval as large as 100K. Such a thermal hysteresis is characteristic of a first order MI transition and was found to vanish with increasing substitution of x. This strongly suggests that increasing x modify the character of this transition to second order. Thermal properties were carried out and confirmed the change of this MI transition with increasing x. In addition, an analysis of the capa(T) data indicate that phonons are the major thermal carriers in these nickelates. Also, the Seebeck coefficient S(T) data revealed features of a conventional metal at higher temperatures with electrons as carriers. An accurate analysis of the S(T) data based on simple band structure arguments indicate a density of states at the Fermi level of 10 POT. 23 (eVcm POT. 3) POT. -1 and energy gaps in the insulating regime close to 20 meV. The character of the first order transition in lightly substituted samples at T DA ORDEM DE T IND. MI was also inferred from the DSC data. The S(T) data confirmed the occurrence of the metal-insulator transition and the already observed change from first to second order character with increasing x. The magnetic susceptibility ípsilon(T) data have been precisely corrected by a systematic subtraction of the R POT.3+-ion contribution of the measured qui(T). Linear adjusts of the corrected curves above 150K where found to fit the Curie-Weiss law with effective magnetic moment of mü IND. EFF ~ 1.76 mü IND. B, which is close to the free-ion value of mü IND. EFF ~ 1.76 mü IND. B (Ni POT. 3+). These results indicate that the Ni POT. 3+ array displays an antiferromagnetic ordering below a well-defined temperature T IND. N, which is close to T IND.MI for Nd IND. 1-X R IND. X NiO IND. 3 and lightly substituted samples. However, the evolution of the susceptibility of the Ni POT. 3+ array displays features which are fingerprints of unconventional antiferromagnetic state. These features, observed mostly below T IND. N, include a field independent irreversibility of qui(T) and a systematic increase of qui(T) with decreasing temperature, resembling that of a paramagnet. An analysis of the electronic contribution to ípsilon(T) resulted in a density of states at the Fermi level close to the one estimated from the S(T) data. These results are discussed within the context of recent experimental results and theories employed to explain the origin of the metal-insulator transition in these nickelates.

Metal-insulator transition is one of the most important properties observed in certain materials which has been studied widely using a wide range of experimental techniques as well as theoretical models. This kind of a transition, observed in several systems, can take place by tuning several parameters such as pressure, temperature or the composition itself. In this thesis we study a few selected transition metal oxide bronzes exhibiting such phenomenon, each of which has a different cause for undergoing the transition. In Chapter 1, we discuss briefly several mechanisms and models that have been used to understand metal-insulator transitions. We also briefly discuss the role of disorder, electron-electron correlations or both to understand the different ways in which such transitions can occur. In Chapter 2, we describe the different experimental as well as theoretical techniques that have been used in this thesis. In Chapter 3, we study the fermi-edge of the NaxWO3 systems, as a function of x, to understand the origin of the metal-insulator transition occurring in this series of compounds. The system undergoes a metal-insulator transition at the critical composition xc=0.25, below which it is found to be insulating. At the lowest temperature, the very low x compounds behave as disordered and correlated materials. Above the transition composition, the compounds behave as disordered and correlated metals. In the insulating regime, close to the critical composition, we find that the system behaves in a way that cannot be described by any known theories for metals or insulators. We have also done a systematic analysis of the Fermi-edge data for the insulating samples as a function of temperature and we find that they cannot be described by any of the known theories for solid-state systems. Further development is necessary in the theoretical side to understand and interpret our data. In Chapter 4, we study the angle-resolved photoemission data for the highly metallic sodium tungsten bronze Na0.8WO3. We have synthesized the single-crystals by high-temperature electrochemical synthesis and we have performed angle-resolved photoemission experiments to understand the band structure of this system. The experimental results have been supported by theoretical calculations. We find that the rigid band model is valid in describing the electronic structure in these systems. We also find the existence of electron-like pockets along certain symmetry directions. Further, photon energy dependent studies on the x=0.8 sample suggest that there is a difference in the surface with the bulk of the sample. The bulk is perfectly periodic and ordered, whereas the surface shows a distortion due to the rotation or deformation of the WO6 octahedra. In Chapter 5, we have studied the electronic structure of the low dimensional molybdenum oxide La2Mo2O7, which is expected to have a charge density wave(CDW)driven metal-insulator transition around 125K. We indeed observed the presence of CDWs in this system, which was observed in the angle-resolved photoemission spectra as back-folding of bands below the transition temperature. We have also studied the temperature evolution of the bands close to the Fermi level and we see a gradually weakening and finally disappearance of the back-folded bands close to and above the transition temperature. We have studied the angle-integrated spectra of this system from which we conclude that La2Mo2O7 is a CDW non-Fermi liquid system. We have also evaluated the total and partial density of states in this system using Vienna ab-initio simulation package. We find the results consistent with our experimental findings. In Chapter 6, we study the metal-insulator transition in another low-dimensional molybdenum oxide KMo4O6, which is expected to show a metal-insulator transition around 120K due to the formation of spin-density waves. We observed back-folding of bands with lower intensities at low temperature, suggesting the formation of spin density waves in the system. The angle-integrated spectra suggested that the system is a non-CDW non-Fermi liquid system. We have also evaluated the density of states and the results are in agreement with our experimental findings. In conclusion we have investigated the electronic structure of different classes of systems and we have given clue to the origin of the metal-insulator transition in these systems.

In this work, optical pump – near-infrared probe and near-infrared pump – mid-infrared probe spectroscopy are used for the investigation of pressure-induced insulator-to-metal transitions in transition metal oxide compounds. The materials under study are α-Fe₂O₃, also known as hematite, and VO₂. Both materials undergo pressure-induced metallization. However, the physical mechanisms of this phase transition are very different for these systems and have not been fully understood up to now. Using ultrafast pump-probe spectroscopy we obtain an insight into the evolution of the band structure and electron dynamics across the insulator-to-metal transition. In the case of VO₂, our near-infrared pump – mid-infrared probe experiments reveal a non-vanishing pumping threshold for photo-induced metallization even at our highest pressures around 20 GPa. This demonstrates the existence of localized charge carriers and the corresponding persistence of a band gap. Besides the threshold behaviour for photo-induced metallization, the carrier relaxation time scale, and the linear reflectivity and transmissivity have been studied under pressure increase. An anomaly in the threshold behaviour as well as the linear reflectivity and transmissivity at a critical pressure around 7 GPa indicates band gap filling under pressure. This is further supported by results obtained under decompression, where the changes of the linear reflectivity turned out to be almost fully reversible. The observations on VO₂ are highly reproducible and can be explained in terms of a pressure-induced bandwidth-driven insulator-to-metal transition. Fe₂O₃ has been studied via optical pump – near-infrared probe spectroscopy up to pressures of 60 GPa. In the pressure range up to 40 GPa, the changes of the response can be explained by photo-induced absorption and bleaching. The pressure dependent study of the relaxation dynamics allows to identify cooling of the electron system as origin of the picosecond relaxation process. A sharp anomaly found in the response of Fe₂O₃ at 40 GPa indicates a strong rearrangement of the electronic band structure which could be explained by an insulator-to-metal phase transition induced by pumping. The successful demonstration of pump-probe experiments in diamond anvil cells using pulses from optical to mid-infrared wavelengths and reaching pressures of several tens of GPa is a good basis for further experimental high-pressure studies. Our results obtained on VO₂ and Fe₂O₃ can serve as a benchmark for the development of advanced material models. / In der vorliegenden Arbeit wird der druckinduzierte Isolator–Metall-Phasenübergang in den Übergangsmetalloxiden α-Fe₂O₃ (Hämatit) und VO₂ mittels ultraschneller Anrege-Abfrage-Spektroskopie (engl. pump-probe spectroscopy) untersucht. Hämatit wird dazu im sichtbaren Spektralbereich angeregt und im nahen Infrarot (NIR) abgefragt, bei VO₂ wurde zur Anregung NIR und zur Abfrage mittleres Infrarot (MIR) verwendet. Beide Materialien werden bei hinreichend hohem Druck metallisch, wobei die jeweils dem Isolator–Metall-Phasenübergang zugrundeliegenden Mechanismen verschieden und noch nicht vollständig verstanden sind. Dies motiviert den Einsatz von ultraschneller Anrege-Abfrage-Spektroskopie, die einen Einblick in die Änderung der Bandstruktur und der Ladungsträgerdynamik während des Isolator–Metall-Übergangs gewährt. Beim Überschreiten eines Schwellenwertes der Anregung wird VO₂ photoinduziert metallisch. In unseren NIR-MIR Anrege-Abfrage-Experimenten zeigt sich, dass der Schwellenwert auch bei den höchsten Drücken dieser Messreihe (ca. 20 GPa) nicht verschwindet. Dies weist auf die Existenz lokalisierter Ladungsträger hin und damit verbunden auf das Fortbestehen der Bandlücke. Neben dem Schwellenwert für photoinduzierte Metallisierung wurden auch die Druckabhängigkeiten der Relaxationsdynamik der Ladungsträger sowie des linearen Reflexions- und Transmissionsvermögens untersucht. Eine Anomalie im druckabhängigen Verlauf des Anrege Schwellenwertes sowie des linearen Reflexions- und Transmissionsvermögens bei einem kritischen Druck von ca. 7 GPa deutet darauf hin, dass durch das Anlegen von Druck Zustände innerhalb der Bandlücke induziert werden. Diese Interpretation wird auch durch während der Dekompression gewonnene Messdaten unterstützt. Die druckinduzierte Änderung des linearen Reflexionsvermögens erwies sich als nahezu vollständig reversibel. Unsere Beobachtungen an VO₂ sind reproduzierbar und lassen sich als druckinduzierter, Bandbreiten-getriebener Isolator–Metall-Übergang nachvollziehen. Fe₂O₃ wurde mittels Anrege-Abfrage-Spektroskopie bei Drücken bis zu 60 GPa untersucht. Änderungen im Druckbereich bis 40 GPa können als Wechselspiel eines photo-induzierten Absorptionsbandes und der photoinduzierten Unterdrückung eines anderen Absorptionskanals erklärt werden. Die druckabhängige Untersuchung der Relaxationsdynamik ermöglicht es, der Relaxation auf der Zeitskala weniger Pikosekunden Kühlungsdynamik als Ursache zuzuordnen. Eine scharfe Anomalie im qualitativen Verlauf des Anrege-Abfrage-Signals von Fe₂O₃ bei einem Druck von 40 GPa weist auf deutliche Änderungen in der elektronischen Bandstruktur hin, welche als Signatur eines photoinduzierten Isolator–Metall Phasenübergangs interpretiert werden können. Die erfolgreiche Demonstration von Anrege-Abfrage-Experimenten in Diamantstempeldruckzellen mit Laserimpulsen vom sichtbaren Spektralbereich bis hin zum mittleren Infrarot und bei Drücken von 20 GPa bis zu 60 GPa liefert die solide Basis für weitergehende Hochdruck-Experimente. Die an VO₂ und Fe₂O₃ erzielten Ergebnisse sind eine gute Grundlage für die Weiterentwicklung der theoretischen Beschreibung solcher Materialsysteme.

Philosophiae Doctor - PhD / Very few systems allow the study of the relationship between structural changes and physical properties in such a clear way as rare earth nickelate ReNi03 perovskites (Re (rare earth) = Pr, Nd, Sm and Gd). Synthesized for the first time by Demazeau et al [1] in 1971 and completely forgotten for almost twenty years, these compounds have regained interest since the discovery of high-temperature superconductivity and giant magnetoresistive effects in other perovskite-related systems. Due to its Metal-Insulator Transition (MIT) and thermochromic properties, the rare earth nickelate perovskite ReNi03 has received a great deal of attention for the past ten years in their thin films form [12]. Such unusual electronic and optical features are all the more interesting since the metal-insulator transition temperature (TMn) can be tuned by changing the Re cation: LaNi03 is metallic. No minimum of the metallic conductivity of Sm0 . ssNd 0.45Ni03, as observed by Gire et al [12] (entropic effect), was reported by Ambrosini and Hamet [11]. It has been suggested by Obradors et al. [13] that changing the rare earth cation in the ReNi03 system, acts as internal chemical pressure (increasing internal pressure by substituting the rare earth cation with another one of larger ionic radius) which can lead, as for the isostatic pressure experiment, to a tunability of the metal-insulator transition temperature [14, 15]. Obradors et al [13] reported on a decrease of T MIT upon increasing isostatic pressure but with remaining metallic properties of PrNi03 and NdNi03 (same magnitude and thermal dependence of the electrical resistivity)

No description available.

No description available.

There is no apparent, dominant interaction in heavy transition metal oxides (TMO), especially in 5d-TMO, where all relevant interactions are of comparable energy scales, and therefore strongly compete. In particular, the spin-orbit interaction (SOI) strongly competes with the electron-lattice and on-site Coulomb interaction (U). Therefore, any tool that allows one to tune the relative strengths of SOI and U is expected to offer an opportunity for the discovery and study of novel materials. BaIrO3 is a magnetic insulator driven by SOI whereas the isostructural BaRuO3 is a paramagnetic metal. The contrasting ground states have been shown to result from the critical role of the strong SOI in the iridate. This dissertation thoroughly examines a wide array of newly observed novel phenomena induced by adjusting the relative strengths of SOI and U via a systematic chemical substitution of the Ru4+(4d4) ions for Ir4+(5d5) ions in BaIrO3, i.e., in high quality single crystals of BaIr1-xRuxO3(0.0 < x < 1.0) . Our investigation of structural, magnetic, transport and thermal properties reveals that Ru substitution directly rebalances the competing energies so profoundly that it generates a rich phase diagram for BaIr1-xRuxO3 featuring two major effects: (1) Light Ru doping (0 < x < 0.15) prompts a simultaneous and precipitous drop in both the magnetic ordering temperature TC and the electrical resistivity, which exhibits metal-insulator transition at around TC. (2) Heavier Ru doping (0.41 < x < 0.82) induces a robust metallic and spin frustration state. For comparison and contrast, we also substituted Rh4+(4d5) ions for Ir4+(5d5) ions in BaIrO3, i.e. BaIr1-xRhxO3(0.0 < x < 0.10), where Rh only reduces the SOI, but without altering the band filling. Hence, this system remains tuned at the Mott instability and is very susceptible to disorder scattering which gives rise to Anderson localization.