Stair-Structured Cu_2–xHo_xO Materials with Adjustable Optical and Magnetic Properties

Abstract

Stair-structured Cu 2−x Ho x O is synthesized by gas− liquid phase chemical deposition and a subsequent heat treatment method. The UV−visible spectrum of the stair-structured Cu 2 O and Cu 2−x Ho x O exhibits strong absorption peaks in the UV region, and the Ho atom doping reduces the band gap of Cu 2 O. Photoluminescence spectroscopy demonstrates that the luminescence intensity of the stair-structured Cu 2−x Ho x O first increases with Ho addition and then decreases as the Ho 3+ concentration increases further. The fluorescence lifetime curves show that the fluorescence lifetime of the stair-structured Cu 2 O samples is shortened by Ho 3+ ion doping. Stair-structured Cu 2−x Ho x O exhibits distinct and stronger room-temperature ferromagnetism, and its saturation magnetization value shows a parabolic trend with the increase of Ho 3+ ion doping concentration. The firstprinciples calculation results show that the magnetic properties of the staircase-structured Cu 2 O are mainly due to the splitting of spin-up and spin-down electrons near the Fermi energy. The density of states shows that the Ho atom doping contributes to the magnetism of the stair-structured Cu 2−x Ho x O sample, and the values of M s of the samples can be regulated by the Ho atom doping concentration. The magnetic properties reflect a strong d−d exchange interaction between the Ho ions.