Molecular Beam Epitaxy of Wurtzite (Ga,Mn)N Films on Sapphire(0001) Showing the Ferromagnetic Behaviour at Room Temperature

Wurtzite (Ga,Mn)N films showing ferromagnetic behaviour at room temperature were successfully grown on sapphire(0001) substrates by molecular beam epitaxy using ammonia as nitrogen source. Magnetization measurements were carried out by a superconducting quantum interference device at the temperatures between 1.8K and 300K with magnetic field applied parallel to the film plane up to 7T. The magnetic-field dependence of magnetization of a (Ga,Mn)N film at 300K were ferromagnetic, while a GaN film showed Pauli paramagnetism like behaviour. The Curie temperatures of a (Ga,Mn)N film was estimated as 940K.Comment: 5 page

Risk Premia in International Equity Markets Revisited

Recent evidence suggests that global equity markets are becoming more risky. We find that much of the apparent increase in international variance and covariance of returns can be attributed to systematic variations in global risk premia correlated across markets, rather than to any fundamental change in the risk attributes of these markets. This result has interest both for practitioners and for those interested in modeling global asset prices

Risk Premia in International Equity Markets Revisited

Recent evidence suggests that global equity markets are becoming more risky. We find that much of the apparent increase in international variance and covariance of returns can be attributed to systematic variations in global risk premia correlated across markets, rather than to any fundamental change in the risk attributes of these markets. This result has interest both for practitioners and for those interested in modeling global asset prices

High TC ferromagnetism in diluted magnetic semiconducting GaN:Mn films

Wurtzite GaN:Mn films on sapphire substrates were successfully grown by use of the molecular beam epitaxy (MBE) system. The film has an extremely high Curie temperature of around 940 K, although the Mn concentration is only about 3 ~ 5 %. Magnetization measurements were carried out in magnetic fields parallel to the film surface up to 7 T. The magnetization process shows the coexistence of ferromagnetic and paramagnetic contributions at low temperatures, while the typical ferromagnetic magnetization process is mainly observed at high temperatures because of the decrease of the paramagnetic contributions. The observed transport characteristics show a close relation between the magnetism and the impurity conduction. The double exchange mechanism of the Mn-impurity band is one of the possible models for the high-TC ferromagnetism in GaN:Mn.Comment: 20 pages, 4 figures, submitted to Physica

Risk Premia in International Equity Markets Revisited

Recent evidence suggests that global equity markets are becoming more risky. We find that much of the apparent increase in international variance and covariance of returns can be attributed to systematic variations in global risk premia correlated across markets, rather than to any fundamental change in the risk attributes of these markets. This result has interest both for practitioners and for those interested in modeling global asset prices

Stock return predictability: A factor-augmented predictive regression system with shrinkage method

<p>To predict stock market behaviors, we use a factor-augmented predictive regression with shrinkage to incorporate the information available across literally thousands of financial and economic variables. The system is constructed in terms of both expected returns and the tails of the return distribution. We develop the variable selection consistency and asymptotic normality of the estimator. To select the regularization parameter, we employ the prediction error, with the aim of predicting the behavior of the stock market. Through analysis of the Tokyo Stock Exchange, we find that a large number of variables provide useful information for predicting stock market behaviors.</p

Risk premia in international equity markets revisited

Recent evidence suggests that global equity markets are becoming more risky. We develop a model to explain risk premia in international equity markets. The model is then used to investigate the changing nature of conditional risk premia and their effect on unconditional global risk. Using this model we find that the increase in international variance and covariance of realized excess returns can be attributed to systematic variations in global risk premia correlated across markets as well. Understanding this additional source of increased global correlation is important. These results have interest both for practitioners and for those interested in modeling global asset prices.Risk premia International asset pricing models Global capital markets Global investments