scholarly journals Composition- and magnetic field-driven antiferromagnetic-weak ferromagnetic transition in Bi1−xCaxFe1−xTixO3 multiferroics

2016 ◽  
Vol 183 ◽  
pp. 69-72 ◽  
Author(s):  
V.A. Khomchenko ◽  
J.A. Paixão
Keyword(s):  
Magnetic Field ◽  
Ferromagnetic Transition ◽  
Weak Ferromagnetic

scholarly journals Reorientation of α-Fe2O3crystallites in an external magnetic field

2014 ◽  
Vol 70 (a1) ◽  
pp. C165-C165
Author(s):  
Michał Stękiel ◽  
Radosław Przeniosło ◽  
Dariusz Wardecki ◽  
Thomas Buslaps ◽  
Jacek Jasiński
Keyword(s):  
Magnetic Field ◽  
Angular Distribution ◽  
External Field ◽  
Intensity Distribution ◽  
Azimuthal Angle ◽  
Magnetic Interaction ◽  
Cylindrical Container ◽  
Ambient Conditions ◽  
X Ray ◽  
Weak Ferromagnetic

The magnetic interaction between the crystallites of weak ferromagnetic α-Fe2O3 has been studied by combining SR based X-ray diffraction with an externally applied magnetic field. The measurements were performed with several polycrystalline α-Fe2O3 [1,2] samples (dry or in suspensions) placed in a half-filled cylindrical container in ambient conditions. The axis of the cylindrical container was oriented vertically parallel to the applied dc magnetic field. The polycrystalline sample had a free surface, so the α-Fe2O3 crystallites were free to move. The full Debye-Scherrer diffraction rings were measured with a 2D pixel detector at the beamline ID-15B at ESRF. In the absence of the magnetic field the intensity distribution over azimuthal angle was a uniform, i.e. there was no texture. The applied maximal field, B=0.9T was too small to change the magnetic ordering of α-Fe2O3 but it was sufficiently strong to reorient large amount of crystallites in order to minimize the angle between their ferromagnetic moment direction and the external field. Pronounced texture patterns with clear maxima in the angular distribution of the intensity across each Debye-Scherrer ring were observed. The observed textured intensity distribution was analyzed quantitatively by using a model based on the magnetic anisotropy observed in single crystals of α-Fe2O3. The analysis yielded two important parameters: (i) the width of the angular distribution of the ferromagnetic moments directions around the external field direction, and (ii) the relative quantity of the crystallites that did reorient in the external field. The α-Fe2O3 samples were also characterized with TEM technique. The analysis of X-ray and TEM studies provide new conclusions about the magnetic interaction between the α-Fe2O3 crystallites [3]. The proposed measurement technique can be applied to study other weak ferromagnetic materials.

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

CRYSTALLINE STRUCTURE AND PHYSICAL PROPERTIES OF UCo2Al3

2004 ◽  
Vol 18 (30) ◽  
pp. 3905-3914
Author(s):  
E. VERDÍN ◽  
R. ESCUDERO
Keyword(s):  
Intermetallic Compound ◽  
Physical Properties ◽  
Single Crystal ◽  
Intermetallic Compounds ◽  
Heavy Fermion ◽  
Ferromagnetic Transition ◽  
Crystallographic Characteristics ◽  
Heavy Fermion Behavior ◽  
Small Single Crystal ◽  
Weak Ferromagnetic

Some intermetallic compounds which contain uranium or cerium present heavy fermion characteristics. Take, for example, in the UM 2 Al 3 ( M = Pd , Ni ) family, superconductivity and magnetism coexist and present heavy fermion behavior. This work presents the crystallographic characteristics and physical properties of a new compound of this family; the intermetallic compound UCo 2 Al 3. Our initial crystallographic studies performed in a small single crystal show that the structure is hexagonal and similar to the UNi 2 Al 3 and UPd 2 Al 3 parent compounds. The space group is P6/mmm with a=5.125 Å and c=4.167 Å crystalline parameters. Measurements of resistivity and magnetization performed on the single crystal reveal that the compound is not superconducting when measured at about 1.8 K. The compound is highly anisotropic and features related to Kondo-like behavior are observed. A weak ferromagnetic transition is observed at a temperature of about 20 K.

Magnetic order and weak ferromagnetic transition in Gd2CuO4

2000 ◽  
Vol 87 (9) ◽  
pp. 5911-5913 ◽  
Author(s):  
J. Mira ◽  
J. Rivas ◽  
A. Butera ◽  
L. B. Steren ◽  
J. M. Garcı́a-Beneytez ◽  
...  
Keyword(s):  
Magnetic Order ◽  
Ferromagnetic Transition ◽  
Weak Ferromagnetic

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

scholarly journals Magnetoresistive study of the antiferromagnetic–weak ferromagnetic transition in single-crystal La2CuO4+δ

2004 ◽  
Vol 30 (5) ◽  
pp. 411-416 ◽  
Author(s):  
B. I. Belevtsev ◽  
N. V. Dalakova ◽  
V. N. Savitsky ◽  
A. S. Panfilov ◽  
I. S. Braude ◽  
...  
Keyword(s):  
Single Crystal ◽  
Ferromagnetic Transition ◽  
Weak Ferromagnetic
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