Birnessite-type MnO₂ Nanowalls and Their Magnetic Properties

Birnessite-type MnO₂ nanowalls have been fabricated on Si(111) substrate by a facile solution method. The XRD pattern indicates that the sample has the typical feature of turbostratic disorder and prefers to grow in the <i>ab</i> plane. The nanowalls are composed of thin flakes distributing uniformly over the surface of the Si(111) substrate. A magnetic transition temperature of 9.2 K is determined. Prominent magnetic anisotropy with the easy magnetization direction in the <i>ab</i> plane is observed at 5 K.