Fabrication of epitaxial CrO2 nanostructures directly on MgO(100) by pulsed laser deposition

Abstract

Single-phase CrO 2 nanostructured thin films have been grown directly on MgO͑100͒ by pulsed laser ablation of a metallic Cr target in an O 2 environment. X-ray diffraction shows that these films are strained and consist of CrO 2 crystallites with two possible epitaxial relationships to the substrate; either CrO 2 ͑110͒ or CrO 2 ͑200͒ is parallel to MgO͑100͒. Scanning electron microscopy and atomic force microscopy reveal orthogonally arranged nanoneedles and platelike structures ͑both 30-50 nm thick͒. X-ray photoemission confirms that the films are primarily CrO 2 covered with a thin CrO 3 overlayer and indicates its complete synthesis without any residual metallic Cr.

Optical and electron paramagnetic resonance properties of native Cr2O3 surface over CrO2

“…The binding energy (E b ) of the broad Cr 2p 3/2 peak at 576.4 eV corresponds to the CrO 2 (Cr 4+ ) state, while the binding energy of the small hump of Cr 2p 3/2 peak lays at 576.8 eV that corresponds to Cr 2 O 3 (Cr 3+ ) state. The formation of the Cr 3+ state over the Cr 4+ surface could not be ruled out, because of metastable character of CrO 2 at the room temperature [2][3][4][5]. The observed binding energy of those oxidation states of Cr ions are in good agreement with the reported binding energy of the bulk CrO 2 [18,19].…”

“…2a. The feature of M s (T) curve is very similar to the pure CrO 2 with ferromagnetic to paramagnetic transition at T C $390 K [3][4][5]20]. 653 nm.…”

“…There are several oxidation states of Cr, but, only the Cr 4+ (CrO 2 ) state has a ferromagnetic properties at room temperature, because of nearly 100% spin polarization at Fermi level, as predicted by theoretical band structure calculation [1][2][3][4][5]. It behaves as a half-metallic ferromagnet up to Curie temperature T C $390 K [6,7].…”

Pulsed laser deposition of half-metallic CrO<inf>2</inf> thin films for spintronic applications

“…PLD can be a very promising tool for the fabrication of high quality thin films of CrOz. It is a versatile method for the stabilization of otherwise metastable phases under non-equilibrium thermodynamic conditions [20][21].…”

dc and high frequency magnetic properties of nanopatterned CoFe2O4 arrays fabricated using sol-gel precursors

“…Low-dimensional magnetic structures of elemental magnets like cobalt, 1,2 nickel, 3,4 alloys like permalloy, 5,6 and metal-oxides 7,8 have been studied extensively in the past. One unavoidable difficulty with such systems is that below a certain length scale they become superparamagnetic, limiting their application potential.…”