Nickel Nanocomposite Thin Films

Abstract

ABSTRACTNickel was deposited on epitaxial TiN matrix layer grown on Si (100) substrate by pulsed laser deposition process (PLD). Transmission electron microscopy (TEM) study shows that nanoparticles formed are single crystals with two kinds of epitaxial relationship with respect to matrix TiN. One is cube on cube, where (200) Ni // (200) TiN // (200) Si and (022) Ni // (022) TiN // (022) Si. The particles grown in this orientation have a trapezoidal morphology in [011] projection. The other involves a 90 ° rotation with respect to [011] direction of TiN matrix (zone axis), where (022) Ni // (200) TiN // (200) Si and (200) Ni // (022) TiN // (022) Si. The particles grown in this rotated orientation have a triangular morphology in [011] projection and a smaller lattice constant compared with that of pure nickel. The possible mechanism of forming these two epitaxial orientations is discussed. Superconducting quantum interference device (SQUID) magnetometer was used for magnetic measurements. In order to investigate the effect of texturing on magnetic properties of nanoparticles, results were compared with those obtained from Ni nanoparticles grown on amorphous Al2O3 matrix layer in previous research. It was found that both blocking temperature and coercivity of Ni nanoparticles grown on epitaxial TiN matrix are significantly higher than that of Ni grown on amorphous Al2O3. The higher value of coercivity is possibly associated with the stronger tendency of crystallographically oriented particles to retain their magnetic moments in the presence of reversing magnetic field.