Home  About us  Contact
 

Temperature Ferromagnetism (temperature + ferromagnetism)

Distribution by Scientific Domains
Physics and Astronomy75%

Selected Abstracts

Fabrication of Vertically Well-Aligned (Zn,Mn)O Nanorods with Room Temperature Ferromagnetism,

ADVANCED MATERIALS, Issue 22 2005
M. Baik
Vertically well-aligned (Zn,Mn)O nanorods (see Figure) that show ferromagnetic behavior at room temperature have been grown on sapphire substrates by chemical vapor deposition. The high optical quality of the nanorods has been demonstrated by photoluminescence spectroscopy. These nanowires may find use in future nanoscale magneto-optic and magneto-electronic applications. [source]

Ferromagnetism in epitaxial Zn0.95Co0.05O films grown on ZnO and Al2O3

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 14 2006
K. Nielsen
Abstract In this article, the possible mechanisms resulting in strong ferromagnetic coupling in transition metal(TM)-doped ZnO and other diluted magnetic semiconductors (DMS) are reviewed and the prerequisites for the observation of room temperature ferromagnetism in TM-doped ZnO are defined. In order to study the ferromagnetic behavior we have grown epitaxial Zn0.95Co0.05O films simultaneously on (0001) ZnO and Al2O3 substrates by laser molecular beam epitaxy at different deposition temperatures. A systematic study of the structural and magnetic properties has been performed to reveal their interdependence. Room temperature ferromagnetism has been found in Zn0.95Co0.05O films grown on ZnO, whereas for films deposited on sapphire only weak ferromagnetic signals have been detected which could not unambiguously be separated from those of the substrate. The different behavior is explained by different structural properties and defect densities in both films. Our experimental findings are in good agreement with a spin split impurity band model, where strong ferromagnetic exchange in ZnO:Co2+ is obtained by a strong hybridization between the magnetic Co2+ ion states and the donor states due to a large density of native defects. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Growth and characterization of Sn doped ZnO thin films by pulsed laser deposition

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2006
E. López-Ponce
Abstract Sn:ZnO thin films with different Sn concentrations were grown by pulsed laser deposition (PLD) onto single-crystal Si(001) substrates at an oxygen pressure of 2 × 10,2 mbar and substrate temperature of 600 °C. The targets used were high density Sn:ZnO pellets with different Sn concentrations produced by mixing ZnO and SnO2 by conventional ceramic routes. A deep structural and electrical characterization was carried out in order to determine the role of an increasing Sn nominal concentration on the ZnO film transport properties. Only films with a nominal 0.1 at% Sn show an improvement of the transport properties, lower resistivity and higher donor concentration, with respect to pure ZnO thin films. For films with larger Sn nominal concentrations segregated SnZnO phases appear that lead to larger film resistivities and no increase in donor concentration. The 0.1 at% Sn film is accordingly a good candidate to study the possible room temperature ferromagnetism when co doping with Mn. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Excitons in ZnO/Zn1,xMnxO quantum wells

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2007
T. Tchelidze
Abstract In order to estimate the perspectives of using ZnO/Zn1,xMnxO quantum wells for reliable high temperature ferromagnetism (specially for increasing Curie temperature in this structure) we investigate excitons in ZnO/Zn1,xMnxO quantum wells. The existence of weak built-in electric field is investigated. Electric field and Coulomb interaction is accounted by means of direct diagonalization. Calculations showed weak dependence of exciton binding energy on well width. Electric field only slightly increases the distance between electron and hole. It rotates ground state excitons and aligns them along the field. Calculations also showed increase of ground state exciton lifetime with increasing well width. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]