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

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

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.

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%.

scholarly journals Field induced crossover in critical behaviour and direct measurement of the magnetocaloric properties of La0.4Pr0.3Ca0.1Sr0.2MnO3

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sagar Ghorai ◽  
Ridha Skini ◽  
Daniel Hedlund ◽  
Petter Ström ◽  
Peter Svedlindh
Keyword(s):  
Magnetic Field ◽  
Temperature Change ◽  
Room Temperature ◽  
Ion Beam ◽  
Mean Field ◽  
Critical Behaviour ◽  
Potential Candidate ◽  
Ferromagnetic Transition ◽  
X Ray ◽  
Lattice Distortions

Abstract La0.4Pr0.3Ca0.1Sr0.2MnO3 has been investigated as a potential candidate for room temperature magnetic refrigeration. Results from X-ray powder diffraction reveal an orthorhombic structure with Pnma space group. The electronic and chemical properties have been confirmed by X-ray photoelectron spectroscopy and ion-beam analysis. A second-order paramagnetic to ferromagnetic transition was observed near room temperature (289 K), with a mean-field like critical behaviour at low field and a tricritical mean-field like behaviour at high field. The field induced crossover in critical behaviour is a consequence of the system being close to a first-order magnetic transition in combination with a magnetic field induced suppression of local lattice distortions. The lattice distortions consist of interconnected and weakly distorted pairs of Mn-ions, where each pair shares an electron and a hole, dispersed by large Jahn–Teller distortions at Mn3+ lattice sites. A comparatively high value of the isothermal entropy-change (3.08 J/kg-K at 2 T) is observed and the direct measurements of the adiabatic temperature change reveal a temperature change of 1.5 K for a magnetic field change of 1.9 T.

PHONONIC APPROACH TO FERROMAGNETIC SEMICONDUCTORS

2006 ◽  
Vol 20 (08) ◽  
pp. 415-425
Author(s):  
JE HUAN KOO ◽  
GUANGSUP CHO
Keyword(s):  
Magnetic Field ◽  
Electrical Resistivity ◽  
Magnetic Field Dependence ◽  
Kondo Lattice ◽  
Ferromagnetic Semiconductors ◽  
Ferromagnetic Transition ◽  
Basic Principles ◽  
Kondo Lattice Model ◽  
The One ◽  
The Magnetic Field

We investigated theoretically ferromagnetic semiconductors. We obtained the Curie temperature Tc for carriers of the one-band and two-band types using a modified Kondo lattice model for paramagnetic to ferromagnetic transition. We also acquired the electrical resistivity and optical conductivity from the basic principles. We calculated the magnetic field dependence of the resistivity in the presence of the external magnetic field, H. A relatively lower value of Tc in the case of ferromagnetic semiconductors in comparison with CMR manganites is elucidated.

Oxygen Isotope Effect in Ordered PrBaMn2O6

2012 ◽  
Vol 190 ◽  
pp. 699-702 ◽  
Author(s):  
A.N. Taldenkov ◽  
N.A. Babushkina ◽  
A.V. Inyushkin ◽  
V.S. Kalitka ◽  
A.R. Kaul
Keyword(s):  
Magnetic Field ◽  
Transition Temperature ◽  
Oxygen Isotope ◽  
Isotope Effect ◽  
Charge Ordering ◽  
Ferromagnetic Transition ◽  
Small Decrease ◽  
Ac Magnetic Susceptibility ◽  
Isotope Substitution ◽  
Systematic Shift

The oxygen isotope effect in ordered half-doped manganite PrBaMn216-18O6 has been investigated. Real and imaginary parts of ac magnetic susceptibility, dc magnetization and magnetoresistance were measured at temperatures from 4.2 to 320 K in applied magnetic field up to 35 kOe. Substantial increase of charge ordering (CO) transition temperature TCO under oxygen isotope substitution 16O 18O and small decrease of ferromagnetic (FM) transition temperature TFM were found. Small systematic shift of ferromagnetic transition temperature in oxygen reduced manganite PrBaMn216 18O5 is also considered. The obtained results are compared with those observed in other manganites demonstrating the large isotope effect.

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