| 1. |
- Gupta, Amita, et al.
(författare)
-
Room temperature ferromagnetism in transition metal (V, Cr, Ti) doped In(2)O(3)
- 2007
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 101:9, s. 09N513-
-
Tidskriftsartikel (refereegranskat)abstract
- Indium oxide is chosen as the host material for doping Ti, V, and Cr transition metal ions. Theoretical calculations based on density functional theory within a local spin density approximation show that V-V separation of 5.6 A is more stable with a strong ferromagnetic coupling. Our calculations clearly predict that substitution of vanadium for indium should yield ferromagnetism in In(2)O(3). Experimentally, (In(0.95)TM(0.05))O(3) (TM=Ti,V,Cr) were prepared using sol-gel as well as solid state reaction methods. Superconducting quantum interference device magnetization measurements as a function of field and temperature clearly showed that the V and Cr doped samples are ferromagnetic with Curie temperature well above room temperature. Thin films deposited by pulsed laser ablation using these materials on sapphire substrates exhibit a preferred 222 orientation normal to the plane of the film. The magnetic moment for (In(0.95)V(0.05))O(3) film deposited in 0.1 mbar oxygen pressure was estimated to be 1.7 mu(B)/V and is comparable to the theoretical value of 2 mu(B)/V.
|
|
| 2. |
- Kobayashi, M., et al.
(författare)
-
Hybridization between the conduction band and 3d orbitals in the oxide-based diluted magnetic semiconductor In2-xVxO3
- 2009
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 79:20, s. 205203-
-
Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of In2-xVxO3 (x=0.08) has been investigated by photoemission spectroscopy and x-ray absorption spectroscopy (XAS). The V 2p core-level photoemission and XAS spectra revealed that the V ion is in the trivalent state, which is the same valence state as that of In in In2O3. The V 3d partial density of states obtained by the resonant photoemission technique showed a sharp peak above the O 2p band. While the O 1s XAS spectrum of In2-xVxO3 was similar to that of In2O3, there were differences in the In 3p and 3d XAS spectra between the V-doped and pure In2O3. The observations give clear evidence for hybridization between the In-derived conduction band and the V 3d orbitals in In2-xVxO3.
|
|
| 3. |
- Nagar, Sandeep, et al.
(författare)
-
Room Temperature Ferromagnetism and Lack of Ferroelectricity in Thin Films of 'Biferroic?' YbCrO3
- 2009
-
Ingår i: Novel Materials and Devices for Spintronics. - : Materials Research Society. - 9781605111568 ; , s. 163-168
-
Konferensbidrag (refereegranskat)abstract
- Search for novel multi-functional materials, especially multiferroics, which are ferromagnetic above room temperature and at the same time exhibit a ferroelectric behavior much above room temperature, is an active topic of extensive studies today Ability to address an entity with an external field, laser beam, and also electric potential is a welcome challenge to develop multifunctional devices enabled by nanoscience While most of the studies to date have been on various forms of Bi and Ba based Ferrites, rare earth chromites are a new class of materials which appear to show some promise However m the powder and bulk form these materials are at best canted antiferromagnets with the magnetic transition temperatures much below room temperature In this presentation we show that thin films of YbCrO3 deposited by Pulsed Laser Deposition exhibit robust ferromagnetic properties above room temperature It is indeed a welcome surprise and a challenge to understand the evolution of above room temperature ferromagnetism in such a thin film The thin films are amorphous in contrast to the powder and bulk forms which are crystalline The magnetic properties are those of a soft magnet with low coercivity We present extensive investigations of the magnetic and ferroelectric properties, and spectroscopic studies using XAS techniques to understand the electronic states of the constituent atoms in this novel Chromite While the amorphous films are ferromagnetic much above room temperature, we show that any observation of ferroelectric property in these films is an artifact of a leaky highly resistive material
|
|
| 4. |
- Noice, L., et al.
(författare)
-
Above room-temperature ferromagnetism in GaN powders by calcinations with CuO
- 2006
-
Ingår i: Mater Res Soc Symp Proc. - : Springer Science and Business Media LLC. - 1558998985 - 9781558998988 ; , s. 62-67
-
Konferensbidrag (refereegranskat)abstract
- Gallium nitride powders were calcined with copper oxide in either air or N2 and analyzed by means of powder X-ray diffraction (XRD), high-resolution parallel illumination (HRTEM) and scanning probe transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDXS), and electron energy loss spectroscopy (EELS) in order to address the structural and electronic effects of Cu-incorporation into GaN. Gallium oxide and multiple copper oxide phases corresponding to the calcination environment were detected. Significant changes in the lattice parameters and electronic structure of the N2-processed GaN indicate incorporation of both copper and oxygen into the GaN lattice as well as changes in the chemical bonding due to the calcinations process. SQUID magnetometer measurements at 300 K demonstrated ferromagnetism in selected samples.
|
|
