Room temperature ferromagnetic properties of dysprosium-doped tris(8-hydroxyquinoline) aluminum: experimental and theoretical investigation

Abstract

Room temperature ferromagnetism was observed in rare earth dysprosium (Dy)-doped tris(8-hydroxyquinoline) aluminum (Alq₃) organic small molecular films. The Dy-doped Alq₃ films were prepared by co-evaporating pure Alq₃ and Dy powders on Si substrates in a vacuum. The maximum room temperature coercive field and the saturation magnetization are about 70 Oe and 9.5 × 10⁻⁶ emu, respectively. The structures were studied by the atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and synchrotron radiation X-ray absorption fine structure (XAFS). The magnetic properties were investigated by the MicroMag Alternating Gradient Magnetometer (AGM), Quantum Design superconducting quantum interference device (SQUID) and first-principles calculations. The room temperature ferromagnetism is ascribed to the magnetic moments induced by the Dy atom and the large energy difference between ferromagnetic and antiferromagnetic coupling.