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We report the observation of ferromagnetic (FM) and antiferromagnetic (AFM) interlayer exchange coupling (IEC) in GaMnAsP-based trilayer structures with out-of-plane magnetic anisotropy. Magnetization and anomalous Hall effect (AHE) measurements show well-resolved magnetization transitions corresponding to the two GaMnAsP layers. Minor loop measurements reveal a characteristic shift caused by IEC in all trilayer samples investigated. Interestingly, the FM IEC changes to AFM IEC for a trilayer with the thinnest (7 nm) top GaMnAsP layer as the temperature increases. The observation of temperature-induced transition of FM and AFM IEC in the same sample suggests the possibility of device applications by controlling the type of IEC in such GaMnAsP-based multilayers.

This paper investigates the causal relationship among electricity supply, fossil fuel consumption, CO2 emissions and economic growth in Nigeria for the period 1971-2009, in a multivariate framework.Using the bound test approach to cointegration, we found a short-run as well as a long-run relationship among the variables with a positive and statistically significant relationship between CO2 emissions and fossil fuel consumption. The findings also indicate that economic growth is associated with increased CO2 emissions while a positive relationship exists between electricity supply and CO2 emissions revealing the poor nature of electricity supply in Nigeria. Further, the Granger causality test results indicate that electricity supply has not impacted significantly on economic growth in Nigeria. The results also strongly imply that policies aimed at reducing carbon emissions in Nigeria will not impede economic growth. The paper therefore concludes that a holistic energy planning and investment in energy infrastructure is needed to drive economic growth. In the long-run however, it is possible to meet the energy needs of the country, ensure sustainable development and at the same time reduce CO2 emissions by developing alternatives to fossil fuel consumption, the main source of CO2 emissions.

This paper examined the existence of interaction between domestic energy consumption and exports in Nigeria by using annual data from 1970 to 2009. We applied cointegration, Granger causality and impulse response functions to capture the relationship. The empirical results indicate that there is significant relationship between domestic energy consumption and exports in the long run. Granger causality tests showed that there is unidirectional causality running from energy consumption to exports. Impulse response functions indicate that shocks to the energy consumption have a positive impact on exports in the longrun. Likewise, expansions on exports were positively related to energy consumption. Therefore, significant improvement in energy production and utilization is expected to stimulate exports and engender economic growth in Nigeria.