Resistive switching effects on the spatial distribution of phases in metal-complex oxide interfaces

In order to determine the key parameters that control the resistive switching mechanism in metal-complex oxides interfaces, we have studied the electrical properties of metal / YBa2Cu3O7-d (YBCO) interfaces using metals with different oxidation energy and work function (Au, Pt, Ag) deposited by sputtering on the surface of a YBCO ceramic sample. By analyzing the IV characteristics of the contact interfaces and the temperature dependence of their resistance, we inferred that ion migration may generate or cancel conducting filaments, which modify the resistance near the interface, in accordance with the predictions of a recent model.Comment: 3 pages, 5 figures, to be published in Physica B. Corresponding author: C. Acha ([email protected]

Interest Rates in Nigeria: An Analytical Perspective

This paper set out to examine the implications of interest rate for savings and investment in Nigeria. It used data obtained from the Central Bank of Nigeria (CBN). Data were analyzed using Pearson's Correlation Coefficient and regression. Evidence showed interest rate as a poor determinant of savings and investment indicating that bank loans are mostly not used for productive purposes. Therefore, bank loans should be channeled to productive investments if interest is to play its catalytic role in the Nigerian economy

Transport mechanism through metal-cobaltite interfaces

The resistive switching (RS) properties as a function of temperature were studied for Ag/La$_{1-x}$Sr$_x$CoO$_3$ (LSCO) interfaces. The LSCO is a fully-relaxed 100 nm film grown by metal organic deposition on a LaAlO$_3$ substrate. Both low and a high resistance states were set at room temperature and the temperature dependence of their current-voltage (IV) characteristics was mea- sured taking care to avoid a significant change of the resistance state. The obtained non-trivial IV curves of each state were well reproduced by a circuit model which includes a Poole-Frenkel element and two ohmic resistances. A microscopic description of the changes produced by the RS is given, which enables to envision a picture of the interface as an area where conductive and insulating phases are mixed, producing Maxwell-Wagner contributions to the dielectric properties.Comment: 13 pages, 5 figures, to be published in APL. Corresponding author: C. Acha ([email protected]

Financial Intermediation by Banks and Economic Growth in Nigeria, 1990-2008

This study investigated the role banks play in economic growth. It used bank deposits and bank credit to the private sector as variables for bank intermediation and real gross domestic product (RGDP) to proxy economic growth. The Regression of RGDP as dependent variable against bank deposit and credit confirmed that banks through their intermediation function contribute to economic growth in Nigeria. The paper therefore recommends that banks should be encouraged to expand credit to the private sector

Non-volatile resistive switching in dielectric superconductor YBCO

We report on the reversible, nonvolatile and polarity dependent resistive switching between superconductor and insulator states at the interfaces of a Au/YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO)/Au system. We show that the superconducting state of YBCO in regions near the electrodes can be reversibly removed and restored. The possible origin of the switching effect may be the migration of oxygen or metallic ions along the grain boundaries that control the intergrain superconducting coupling. Four-wire bulk resistance measurements reveal that the migration is not restricted to interfaces and produce significant bulk effects.Comment: 4 pages, 4 figures, corresponding author: C. Acha ([email protected]

Electrical resistivity of the Ti4O7 Magneli phase under high pressure

We have measured resistivity as a function of temperature and pressure of Ti4O7 twinned crystals using different contact configurations. Pressures over 4kbar depress the localization of bipolarons and allow the study of the electrical conduction of the bipolaronic phase down to low temperatures. For pressures P > 40 kbar the bipolaron formation transition is suppressed and a nearly pressure independent behavior is obtained for the resistivity. We observed an anisotropic conduction. When current is injected parallel to the principal axis, a metallic conduction with interacting carrier effects is predominant. A superconducting state was not obtained down to 1.2 K, although evidences of the proximity of a quantum critical point were noticed. While when current is injected non-parallel to the crystal's principal axis, we obtained a logarithmic divergence of the resistivity at low temperatures. For this case, our results for the high pressure regime can be interpreted in the framework of interacting carriers (polarons or bipolarons) scattered by Two Level Systems.Comment: 9 Revtex pages, 12 EPS figures included, submitted to The European Physical Journal B. Contact author: C. Acha (e-mail address: [email protected]

Spatio-temporal changes of land use land cover dynamics and its implication on urban flood vulnerability in Makurdi, Nigeria

Makurdi as one of the major city located on the flood plain along river Benue in Nigeria is exposed to the recurring flooding events which results to loss of life and properties. Hence there is need to analysed the spatio-temporal Land use Land cover (LULC) Dynamics and its implication on Urban Flood Vulnerability in Makurdi, Nigeria. LULC change was determined using Remote Sensing techniques and Geographic Information System; the land use was classified into five classes from 1986 - 2016 to monitor the changes that have taken place over time and space. Digital Elevation Model (DEM) of the study area were created and classified into three classes; High, Moderate, and Low risk areas. Soil infiltration analyses were performed in some selected sample points across the study area. The result revealed that Wadata area have a high bulk density and moisture content of 1.46g and 89% respectively indicating low rate of infiltration thereby accelerating runoff and flood event. Similarly, from the interpretation of the different epoch of Landsat images it shows that built-up areas have been on increase from 4.82% in 1986 to 35.36% in 2016 which has resulted to encroachment into the flood plain. The classified DEM -slope shows that about 40016.09 hectares (48.43%) of the land mass is within the flood plain. Consequently, there is need to identify and developed strategies for sustainable urban flood plain development for the attainment of resilience urban flood.Keywords: Spatio-temporal, LULC, Urban Flood, Bulk Density and encroachmen

Implications of Monetary Policy for Banks’ Assets in Nigeria

Monetary policy is implemented with the main objective of economic stability and banks are the primary channel through which this policy influences economic variables. It is argued that the extent to which monetary policy goals are attained is predicated on the responsiveness of banks to it. The study therefore investigates the implications of monetary policy for Nigerian banks. To ascertain the influence pattern of monetary policy on banks, the study uses monetary policy rate and lending rates as monetary policy proxies. While banks asset is represented in the model by aggregate bank lending. Correlation and regression analyses were used to analyze data. The correlation result showed a negative relationship between aggregate bank lending (AGL), monetary policy rate (MPR), lending rate (LDR) and inflation rate (IFR). The regression analysis result confirms this, as monetary policy rate (MPR) relates negatively with loans in Nigeria. This means that the raising of the MPR and the attendant increases in lending rates will deter borrowers. The negative relationship between AGL and IFR, which is contrary to expectation, denotes the existence of a weak link between bank loans and the general market prices. The study concludes that monetary targeting could be effective in Nigeria in influencing bank lending but plays little role in inflation control and suggests refocusing on inflation targeting. Keywords: Monetary policy rate, lending rate, inflation, bank loans, loan portfoli

Banks and Economic Growth in Nigeria

The study examines the contribution of banks in Nigeria to the growth of the economy. It used bank savings mobilization and credit to the real sector as proxy for banks contribution while gross domestic product growth rate proxies’ economic growth. Before correlation analysis and regression were used to test hypothesis, diagnostic tests were carried out on the variables to ensure stationarity and examine the cointegration properties of the model. Augmented Dickey-Fuller test was used to test stationarity while Trace statistic and Eigenvalue test were used to assess cointegration. Results show an insignificant impact of banks intermediation variables on economic growth. The study therefore concludes that the poor performance of these variables indicate that other variables such as human resources, social infrastructure, political stability and technology may play more robust role in economic growth in Nigeria than banks. In the light of this, urgent improvement in social infrastructure especially power supply and reversal of the decline in education were recommended