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We report results of magnetization and differential scanning calorimetry measurements in the ferromagnetic shape memory alloy Ni54Fe19Ga27. This alloy undergoes an austenite-martensite phase transition in its ferromagnetic state. The nature of the ferromagnetic state, both in the austenite and the martensite phase, is studied in detail. The ferromagnetic state in the martensite phase is found to have higher anisotropy energy as compared with the austenite phase. The estimated anisotropy constant is comparable to that of a well-studied ferromagnetic shape memory alloy system NiMnGa. Further, the present study highlights various interesting features accompanying the martensitic transition (MT). These features suggest the possibility of either a premartensitic transition and/or an inter-MT in this system. [ABSTRACT FROM AUTHOR]

The surface photovoltage generation mechanism is found to be the opposite for the epitaxial ZnO layer side compared to that of the GaP substrate side at the heterojunction due to the presence of an interfacial layer of GaOx. The low temperature (10 K) surface photovoltage spectroscopy spectrum for the ZnO layer with good crystalline quality is dominated by the free-A excitonic feature FXA. On the other hand, it is dominated by the donor bound excitonic feature DoXA for ZnO layers with relatively poorer crystalline qualities. We have also observed a feature in 10 K SPS data that can be related to the first excited state (n = 2) of free-A exciton (FX) and/or free-C exciton (FXC) features. Larger inhomogeneous broadening caused by strain and poorer crystalline quality hinders the observation of separate feature corresponding to free-B excitonic feature FXB. The temperature dependence of energy positions and broadening parameters are very well described by the scattering of an exciton with E2(low) and A1(LO) phonons present in ZnO. It also indicates that there is no dependence of exciton–phonon coupling strength on the crystalline quality of ZnO layers. [ABSTRACT FROM AUTHOR]

The effects of swift heavy ion (SHI) irradiation in epitaxial thin film of magneto-electric GaFeO3 (GFO) deposited on (0 0 1) oriented yttria-stabilized zirconia substrate are reported. The structural modifications during the irradiation are studied using in-situ x-ray diffraction and it is observed that SHI induces stress. Thus the induced stress leads to the formation of elongated array of GFO nano-grains and the crystallographic tilting between film and substrate as observed from reciprocal space mapping (RSM). The epitaxy is found to persist even with a dose of ions cm−2 from the RSM. The irradiation is found to affect the magnetic properties of GFO viz., the transition temperature and the redistribution of iron at soft and hard magnetic sites. These observations indicate the possibility of tuning structural and magnetic properties of GFO with SHI. [ABSTRACT FROM AUTHOR]