Magnetic analysis of MnAs films grown on GaAs and Si substrates for potential spintronics and magnetocaloric applications

• Published in: Journal of magnetism and magnetic materials Vol. 322; no. 9; pp. 1565 - 1568
• Main Authors: Solzi, Massimo, Pernechele, Chiara, Ghidini, Massimo, Natali, Marco, Bolzan, Marco
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.2010; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Ferromagnetic materials; Gallium arsenide; Magnetic properties; Magnetic properties and materials; Magnetic properties of monolayers and thin films; Magnetic properties of surface, thin films and multilayers; Magnetic semiconductors; Magnetic-phase transitions; Magnetocaloric effect; Manganese arsenide; Physics; Semiconductors; Silicon films; Silicon substrates; Studies of specific magnetic materials; Thin films; Transformations; Magnetocaloric effect; Manganese arsenide; Magnetic-phase transitions; Epitaxial layers; Phase transformations; Magnetic transitions; Magnetic semiconductors; Thickness; Hexagonal lattices; Magnetocaloric effects; Manganese arsenides; Thermal hysteresis; MOVPE method; Orthorhombic lattices; Ferromagnetic-paramagnetic transitions; Spintronics
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2009.09.013

We present a magnetic characterisation of MnAs films grown by MOVPE on semiconductor substrates, for comparing the effect of thickness and substrate on their magnetic and magneto-thermal properties, with particular focus on the nature of the magneto-structural transition between the ferromagnetic hexagonal α-phase and the paramagnetic orthorhombic β-phase. The nature of this transformation depends on the presence of strain and turns out to be of second-order type for epitaxial–crystalline MnAs/(0 0 1)GaAs films and closer to a first-order type for polycrystalline MnAs/SiO 2/Si films. The magnetocaloric effect at the transition has been estimated for thin film samples, resulting appreciably lower than that of bulk MnAs.