Size effect on the structural and ferromagnetic transition temperature of La0.6A0.4MnO3manganites

1999 ◽  
Vol 70 (3) ◽  
pp. 211-222 ◽  
Author(s):  
N. Abdelmoula ◽  
J. Dhahri ◽  
K. Guidara ◽  
E. Dhamri ◽  
J. C. Joubert
Keyword(s):  
Transition Temperature ◽  
Size Effect ◽  
Ferromagnetic Transition

Structure, Electrical and Magnetic Properties of Thin Films of La1−xMxMnO3 on Si

1999 ◽  
Vol 562 ◽  
Author(s):  
N. N. Mateeva ◽  
P. C. Hogan ◽  
K. H. Dahmen
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Transition Temperature ◽  
Buffer Layers ◽  
Ferromagnetic Transition ◽  
Electrical And Magnetic Properties ◽  
Insulator Metal Transition ◽  
Composition Structure

ABSTRACTThin films of lanthanum manganates doped with Ca2+, Sr2+, Ba2+ and Pb2+ have been deposited on Si(100) substrate and their electrical and magnetic properties were discussed with respect to the composition, structure and nature of the dopant. Buffer layers of YSZ and La0.8Al0.2O3 were employed and their effect on the materials was studied. Interesting magnetotransport properties were found in some of the films, where there is a large difference between the insulator-metal transition temperature and a ferromagnetic transition temperature.

Decrease of Ferromagnetic Transition Temperature in Nonstoichiometric SrRu1−v O3 Perovskites

2002 ◽  
pp. 303-311
Author(s):  
B. Dabrowski ◽  
P. W. Klamut ◽  
O. Chmaissem ◽  
S. Kolesnik ◽  
M. Maxwell ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Ferromagnetic Transition

Effect of Low Temperature Annealing on High Field Magnetoresistance and Hall effect in (Ga, Mn)As Dilute Magnetic Semiconductors

2004 ◽  
Vol 831 ◽  
Author(s):  
K. Ghosh ◽  
Mohammad Arif ◽  
T. Kehl ◽  
R. J. Patel ◽  
S. R. Mishra ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Low Temperature ◽  
High Field ◽  
Magnetic Semiconductors ◽  
Magnetic Semiconductor ◽  
Dilute Magnetic Semiconductors ◽  
Epitaxial Thin Films ◽  
Ferromagnetic Transition ◽  
Optimal Temperature ◽  
Low Temperature Annealing

ABSTRACTIn this paper we report the effect of low temperature annealing on the high field magnetotransport properties of epitaxial thin films of (Ga, Mn)As Dilute Magnetic Semiconductor (DMS) with low concentration (1.5 %) of Mn doping, which results in a ferromagnetic insulator. Annealing at an optimal temperature enhances the conductivity, carrier concentration, and ferromagnetic transition temperature. The field dependence of magnetoresistance is different below and above the ferromagnetic transition temperature. An attempt is made to analyze the data using a theoretical model proposed by Kaminski and Das Sarma [1].

Effect of Zn substitution on para- to ferromagnetic transition temperature in La0.67Ca0.33Mn1−xZnxO3 colossal magnetoresistance materials

2000 ◽  
Vol 87 (9) ◽  
pp. 5034-5036 ◽  
Author(s):  
V. P. S. Awana ◽  
E. Schmitt ◽  
E. Gmelin ◽  
Anurag Gupta ◽  
A. Sedky ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Colossal Magnetoresistance ◽  
Ferromagnetic Transition ◽  
Zn Substitution

EFFECTS OF PHOTO-EXCITATION AND MAGNON SCATTERING ON FERROMAGNETIC TRANSITION TEMPERATURE OF THE DILUTED MAGNETIC SEMICONDUCTOR (Ga1 - x, Mnx)As

2011 ◽  
Vol 25 (04) ◽  
pp. 273-280 ◽  
Author(s):  
CHERNET AMENTE ◽  
P. SINGH
Keyword(s):  
Transition Temperature ◽  
Spin Wave ◽  
Wave Scattering ◽  
Diluted Magnetic Semiconductor ◽  
Magnetic Semiconductor ◽  
Ferromagnetic Transition ◽  
Photon Irradiation ◽  
Model Hamiltonian ◽  
Diluted Magnetic ◽  
System Properties

Effects of photo-excitation and spin-wave scattering on magnetization of the diluted magnetic semiconductor (DMS) ( Ga , Mn ) As are theoretically studied. Green function formalism is used to find expression for magnetization and ferromagnetic transition temperature TC starting with a model Hamiltonian consisting of magnons, photons and an interaction of magnons with photons. According to our calculation, there is TC in the absence of magnetic impurity, x = 0, indicating that there could be electronically unpaired influential carriers/holes induced by photon irradiation resulting in residual itinerant band magnetization which can be revealed by experiments. Unusual upturn in magnetization near 0 K temperature values for larger magnon–photon coupling constant is also indicated. Moreover, enhancement of magnetization is established with increase in impurity concentration and even further in the presence of photon–magnon coupling which however decreases due to spin-wave scattering. This leads to the conclusion that at lower temperatures photon irradiation and at higher temperatures spin-wave scattering could affect the system properties predominantly.

Reformulation of pairing theory

1988 ◽  
Vol 02 (05) ◽  
pp. 1101-1105 ◽  
Author(s):  
Miklos GULACSI ◽  
Zsolt GULACSI
Keyword(s):  
Transition Temperature ◽  
Size Effect ◽  
Layer Thickness ◽  
Short Communication ◽  
Cooper Pairing ◽  
Two Dimensional ◽  
Critical Transition ◽  
Critical Transition Temperature ◽  
Quantum Size ◽  
Natural Way

The original Cooper pairing theory is reformulated for electrons confined in a layer. This analysis is motivated by the quasi-two-dimensional character of the oxidic superconductors, in case of which the extension of the initial (3D) Cooper framework is practically impossible. By considering the electrons moving in a flat box, due to quantum size effect the properties of these oxidic superconductors can be explained in a natural way. In this short communication we will concentrate to the variation of the critical transition temperature due to the layer thickness and to the number of conduction (Cu-O) planes. The results are confirmed by the experiment. This being an evidence for the presence of the charge confinement effect in the oxidic superconductors.

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