scholarly journals Influence of magnetic field on the paramagnetic-ferromagnetic transition in aLa1−xCaxMnO3(x≈0.25)crystal: Ultrasonic and transport studies

2006 ◽  
Vol 74 (5) ◽  
Author(s):  
B. I. Belevtsev ◽  
G. A. Zvyagina ◽  
K. R. Zhekov ◽  
I. G. Kolobov ◽  
E. Yu. Beliayev ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Ferromagnetic Transition ◽  
Transport Studies

Continuous Two-Dimensional Melting of Vortex-Solid in High Temperature Superconductors

1989 ◽  
Vol 169 ◽  
Author(s):  
N.-C. Yeh
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
Defect Density ◽  
High Temperature Superconductors ◽  
Finite Size ◽  
Sample Thickness ◽  
Zero Field ◽  
Two Dimensional ◽  
Thermally Induced ◽  
Transport Studies

AbstractA model of continuous two-dimensional melting in the mixed state of high temperature superconductors is proposed. Two-dimensional melting sets in at a cross-over temperature Tx(H) below the three-dimensinal phase transition Tx(H) due to finite size effects, and Tx(H) is a function of the sample thickness (lc), applied magnetic field (H), and k(= λ/ξ) For a given zero-field transition temperature Tc0 and material properties, (such as defect density), the onset temperature of 2D-melting (Tx(H)) decreases with decreasing sample thickness and increasing magnetic field. In transport studies, thermally induced melting is further complicated by the depinning effect of high current densities.

Enhancement of the CMR Effect Near Room Temperature by Defects and Structural Transitions in La1−x−yCaxSryMnO3

1999 ◽  
Vol 602 ◽  
Author(s):  
S. Kolesnik ◽  
B. Dabrowski ◽  
Z. Bukowski ◽  
J. Mais
Keyword(s):  
Magnetic Field ◽  
Room Temperature ◽  
Structural Phase ◽  
Zero Magnetic Field ◽  
Ferromagnetic Transition ◽  
Spin Lattice ◽  
Preparation Conditions ◽  
Close Proximity ◽  
Selection Of ◽  
Structural Phase Transformations

AbstractWe have studied magnetoresistance of a series of La1−xSrxMnO3 and La1−x−yCaxSryMnO3 samples, for which structural and ferromagnetic transformation temperatures are in close proximity. On cooling in zero magnetic field, we observe a rapid increase of resistivity just above TC for La1−xSrxMnO3 samples with x < 0.1425 and x ≤ 0.1725 due to the O*-O' and R-O* - structural phase transformations, respectively. This increase is followed by a rapid decrease due to the ferromagnetic transition. The applied magnetic field significantly shifts the ferromagnetic transition to higher temperatures and suppresses the structure-related resistivity increase. We show that a combination of structural and ferromagnetic transitions gives rise to an enhancement of the negative magnetoresistance due to strong spin-lattice coupling. By choosing a proper composition, the enhancement can be optimized to appear in relatively low magnetic fields. A proper selection of Sr and Ca contents in La1−x−yCaxSryMnO3 and preparation conditions leads to an enhancement of the magnetoresistance effect at room temperature.

Irreversible magnetic-field-induced antiferromagnetic to ferromagnetic transition in Nd5Ge3

2010 ◽  
Vol 405 (1) ◽  
pp. 180-185 ◽  
Author(s):  
Takanori Tsutaoka ◽  
Akira Tanaka ◽  
Yasuo Narumi ◽  
Masahiro Iwaki ◽  
Koichi Kindo
Keyword(s):  
Magnetic Field ◽  
Ferromagnetic Transition

Intrinsic Position Sensing of a Ni-Mn-Ga Microactuator

2008 ◽  
Author(s):  
Daniel Auernhammer ◽  
Manfred Kohl ◽  
Berthold Krevet ◽  
Makoto Ohtsuka
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Martensitic Transformation ◽  
Inhomogeneous Magnetic Field ◽  
Ferromagnetic Transition ◽  
Ferromagnetic Shape Memory Alloy ◽  
Position Sensing ◽  
Double Beam ◽  
Ferromagnetic Shape Memory ◽  
Magneto Resistance

This paper presents an investigation of the intrinsic magnetoresistance of a ferromagnetic shape memory alloy (FSMA) microactuator for position sensing. The microactuator is designed as a double-beam cantilever of a polycrystalline Ni-Mn-Ga thin film, which exhibits both, a martensitic transformation in the temperature range 333–359 K and a ferromagnetic transition at about 370 K. The microactuator is placed in the inhomogeneous magnetic field of a miniature Nd-Fe-B magnet causing a mixed thermo-magneto-resistance effect upon actuation. The maximum in-plane magnetic field is about 0.38 Tesla. In this case, the maximum magnetoresistance (MR) is 0.19%.

MAGNETIC FIELD INDUCED INSTABILITIES IN LOCALIZED TWO-DIMENSIONAL ELECTRON SYSTEMS

2009 ◽  
Vol 23 (12n13) ◽  
pp. 2708-2712
Author(s):  
MATTHIAS BAENNINGER ◽  
ARINDAM GHOSH ◽  
MICHAEL PEPPER ◽  
HARVEY E. BEERE ◽  
IAN FARRER ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
Magnetic Fields ◽  
Temperature Dependence ◽  
Electron Density ◽  
Two Dimensional ◽  
Electron Systems ◽  
Dimensional Electron ◽  
Transport Studies ◽  
Two Dimensional Electron Systems

The results of extensive transport studies in localized regime of mesoscopic two-dimensional electron systems (2DES) with varying disorder are presented. A quick overview of previously achieved result is given. The main focus is on the observation of density dependent instabilities manifested by strong resistance oscillations induced by high perpendicular magnetic fields B⊥. While the amplitude of the oscillations is strongly enhanced with increasing B⊥, their position in electron density remains unaffected. The temperature dependence of resistivity shows a transition from an activated behaviour at high temperature to a saturated behaviour at low T. In the positions of resistance minima, the T dependence can even become metal-like (dρ/dT > 0). The activation energies obtained from the high T behaviour exhibit a formation of plateaux in connection with the resistance oscillations when analyzed as a function of electron density. We suggest the interplay between a strongly interacting electron phase and the background disorder as a possible explanation for our observation.

Photoluminescence and transport studies of wide (InGa)As/InP quantum wells in high magnetic field

1990 ◽  
Vol 229 (1-3) ◽  
pp. 512-514 ◽  
Author(s):  
D.G. Hayes ◽  
M.S. Skolnick ◽  
L. Eaves ◽  
P.E. Simmonds ◽  
L.L. Taylor ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Quantum Wells ◽  
High Magnetic Field ◽  
Transport Studies
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