Magnetic Solitons in the 1-D Antiferromagnetic Chains of Li2Mn0.98Fe0.02F5 and Na2Mn0.98Fe0.02F5

1996 ◽  
Vol 51 (8) ◽  
pp. 939-949 ◽  
Author(s):  
Ch. Frommen ◽  
M. Mangold ◽  
J. Pebler
Keyword(s):  
Magnetic Susceptibility ◽  
Short Range ◽  
Domain Walls ◽  
Thermal Excitation ◽  
Temperature Dependent ◽  
Local Anisotropy ◽  
Relaxation Effects ◽  
Exponential Temperature Dependence ◽  
Moving Domain ◽  
Ferromagnetic Ordering

Abstract Measurements of the 57Fe Mössbauer effect and magnetic susceptibility have been performed on 57Fe-doped quasi-1-d antiferromagnetic chains of Li2MnF5 and Na2MnF5 as a function of temperature. The Mössbauer spectra, fitted by the Blume-Tjon model, show definite relaxation effects near the Neel temperature, which are attributed to short-range order with temperature-dependent relax-ation times. The soliton model of non-linear excitations was applied. Experimental data confirm the predicted exponential temperature dependence of the thermal excitation of moving domain walls. From the activation energies E2A/k2 as a function of 1-d exchange energies J/k the local anisotropy energy D/k of -3.7(2) K was derived on the basis of sine-Gordon theory. This result is in fair agreement with -3.5(1) K previously derived from magnetic susceptibility measurements. In the light of our results there is some evidence that at low bridging angle ß ≈ 102(5)° a phase-transition from antiferromagnetic to ferromagnetic ordering occurs.

Magnetic Studies on the 1-D Antiferromagnetic Chains of enH2Mn(Fe)F5

1995 ◽  
Vol 50 (11) ◽  
pp. 1627-1637 ◽  
Author(s):  
C. Frommen ◽  
L. Schröder ◽  
U. Bentrup ◽  
W. Massa ◽  
J. Pebler
Keyword(s):  
Domain Walls ◽  
Relaxation Times ◽  
Magnetic Ordering ◽  
Thermal Excitation ◽  
Magnetic Studies ◽  
Local Anisotropy ◽  
Magnetic Susceptibilities ◽  
Relaxation Effects ◽  
Exponential Temperature Dependence ◽  
Moving Domain

Measurements of the 57Fe Mössbauer effect and of magnetic susceptibilities have been performed on the 57Fe doped or pure quasi-1-d antiferromagnetic chain compound enH2MnF5 as a function of temperature. Particular attention was paid to the regions very near the Néel point at TN = 14.5(5) K. The Mössbauer spectra fitted by the Blume-Tjon model show definite relaxation effects, which are attributed to short-range order with temperature-dependent relaxation times. The soliton model of non-linear excitations was applied. Experimental data confirm the predicted exponential temperature dependence of the thermal excitation of moving domain walls. From the activation energy EA/k = 184(5) K and the 1-d exchange energy J/k = -13.6(2) K a local anisotropy energy D/k of -2.4 (3) K was obtained which is smaller than D/k = -3.5 K derived from our single crystal measurements of magnetic susceptibilities. Within the 3-d magnetic ordering the interchain interaction amounts to J′/k ≈ 0.22(4) K (J′/J = 15.8 10-3). A zero-spin reduction ⊿S/S equal to 17% was obtained. 1-d correlations are observed for TN<T< |J|S (S + 1)/k ≈ 78 K, and a crystallographic phase transition at 216 K was indicated in the magnetic properties as well as by DSC and X-ray powder diffraction measurements.

Magnetism of Alkalitetrafluoromanganates (III) AMnF4 (A = K, Rb, Cs): Neutron Diffraction, Mössbauer and Magnetization Investigations

1993 ◽  
Vol 48 (11) ◽  
pp. 1054-1072 ◽  
Author(s):  
Michel Molinier ◽  
Christoph Frommen ◽  
Werner Massa ◽  
Jürgen Pebler ◽  
Thierry Roisnel
Keyword(s):  
Neutron Diffraction ◽  
Magnetic Hyperfine Field ◽  
Thermal Excitation ◽  
Spin Orientation ◽  
Domain Wall Dynamics ◽  
Out Of Plane ◽  
Exponential Temperature Dependence ◽  
Jahn Teller ◽  
Magnetic Spin ◽  
Ordered Layers

Abstract The magnetic properties of the d4 Jahn-Teller systems AIMnIIIF4 with layered structures were investigated. Neutron diffraction on powders of KMnF4 and RbMnF4 revealed different antiferro-magnetic spin arrangements below TN = 4.5 K and 2.3 K, respectively: for KMnF4 canted antiparallel along a and b, for RbMnF4 parallel along a and antiparallel along b, in both cases parallel along c, the stacking direction of layers. Mössbauer investigations on 57Fe doped KMnF4 confirmed a spin orientation approximately within the layer plane. A discussion is given of the contributions to the magnetic hyperfine field and the Mössbauer linewidth in quasi-two-dimensional antiferromagnets with Ising anisotropy due to thermal excitation of domain wall dynamics (solitons). The experimental data seem to confirm the predicted exponential temperature dependence of the linewidth. From magnetization measurements on powders and a single crystal of KMnF4 the 2-d exchange energy and the out-of-plane and in-plane anisotropies could be extracted. In addition, from susceptibility measurements the exchange energies of NaMnF4 , RbMnF4 and CsMnF4 were calculated. A linear dependence of these exchange energies (positive for ferromagnetic CsMnF4 , negative for the other AMnF4 compounds) on the cos2 of the Mn-F-Mn bridge angle is observed and compared with the behaviour of the AFeF4 compounds which is also linear but with reverse sign of the slope. The specific superexchange mechanisms active in Jahn-Teller systems with antiferrodistortively ordered layers are suggested to be responsible for these findings.

Ternary Antimonides RE4T7Sb6 (RE=Gd–Lu; T =Ru, Rh) with Cubic U4Re7Si6-type Structure

2013 ◽  
Vol 68 (9) ◽  
pp. 971-978 ◽  
Author(s):  
Inga Schellenberg ◽  
Ute Ch. Rodewald ◽  
Christian Schwickert ◽  
Matthias Eul ◽  
Rainer Pöttgen
Keyword(s):  
Magnetic Susceptibility ◽  
Single Crystal ◽  
Magnetic Moment ◽  
Induction Furnace ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Antiferromagnetic Ordering ◽  
Arc Melting ◽  
Intermediate Valent

The ternary antimonides RE4T7Sb6 (RE=Gd-Lu; T =Ru, Rh) have been synthesized from the elements by arc-melting and subsequent annealing in an induction furnace. The samples have been characterized by powder X-ray diffraction. Four structures were refined on the basis of single-crystal X-ray diffractometer data: U4Re7Si6 type, space group Im3m with a=862.9(2) pm, wR2=0.0296, 163 F2 values for Er4Ru7Sb6; a=864.1(1) pm, wR2=0.1423, 153 F2 values for Yb4Ru7Sb6; a=872.0(2) pm, wR2=0.0427, 172 F2 values for Tb4Rh7Sb6; and a=868.0(2) pm, wR2=0.0529, 154 F2 values for Er4Rh7Sb6, with 10 variables per refinement. The structures have T1@Sb6 octahedra and slightly distorted RE@T26Sb6 cuboctahedra as building units. The distorted cuboctahedra are condensed via all trapezoidal faces, and this network leaves octahedral voids for the T1 atoms. The ruthenium-based series of compounds was studied by temperature-dependent magnetic susceptibility measurements. Lu4Ru7Sb6 is Pauli-paramagnetic. The antimonides RE4Ru7Sb6 with RE=Dy, Ho, Er, and Tm show Curie-Weiss paramagnetism. Antiferromagnetic ordering occurs at 10.0(5), 5.1(5) and 4.0(5) K for Dy4Ru7Sb6, Ho4Ru7Sb6 and Er4Ru7Sb6, respectively, while Tm4Ru7Sb6 remains paramagnetic. Yb4Ru7Sb6 is an intermediate-valent compound with a reduced magnetic moment of 3.71(1) μB per Yb as compared to 4.54 μB for a free Yb3+ ion

MAGNETIC BEHAVIOUR OF UPdAl, UCuGa AND UCuSn

1993 ◽  
Vol 07 (01n03) ◽  
pp. 850-854 ◽  
Author(s):  
V.H. TRAN ◽  
R. TROĆ
Keyword(s):  
Electrical Resistivity ◽  
Magnetic Susceptibility ◽  
Low Temperatures ◽  
Magnetic Behaviour ◽  
Type Structure ◽  
Complex Structures ◽  
Temperature Dependent ◽  
Antiferromagnetic Ordering

Magnetic susceptibility and electrical resistivity have been measured on UCuGa, UCu1+xSn1−x, (x=0 and 0.1), and UPdAl. The first two compounds, crystallizing in the hexagonal CaIn2-type structure, show at low temperatures an antiferromagnetic ordering probably with complex structures. UPdAl, which adopts the orthorhombic TiNiSi-type structure, was found to be a weakly temperature-dependent paramagnet down to 4.2 K.

Magnetic properties of undoped and Co-doped n-type β–FeSi2.5 single crystals

2002 ◽  
Vol 17 (11) ◽  
pp. 2960-2965 ◽  
Author(s):  
E. Arushanov ◽  
L. Ivanenko ◽  
D. Eckert ◽  
G. Behr ◽  
U. K. Rößler ◽  
...  
Keyword(s):  
Activation Energy ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
External Field ◽  
Single Crystals ◽  
Spin Glasses ◽  
Paramagnetic Centers ◽  
Temperature Dependent ◽  
Paramagnetic Curie Temperature ◽  
Co Doped

Results of magnetization and magnetic susceptibility measurements on undoped and Co-doped FeSi2.5 single crystals are presented. The temperature dependence of the magnetic susceptibility of the Co-doped sample in the range of 5–300 K can be explained by temperature-dependent contributions due to paramagnetic centers and the carriers excited thermally in the extrinsic conductivity region. The values of the paramagnetic Curie temperature and activation energy of the donor levels were estimated. It is also shown that the magnetic susceptibility of Co-doped samples cooled in zero external field and in a field are different. This resembles the properties of spin-glasses and indicates the presence of coupling between magnetic centers.

Variations in magnetic properties of Mexican serpentinites and related micro-textures 

2021 ◽  
Author(s):  
Sandra B. Ramírez-García ◽  
Luis M. Alva-Valdivia
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Anisotropy Of Magnetic Susceptibility ◽  
Ultramafic Rocks ◽  
Magnetic Carrier ◽  
Temperature Dependent ◽  
Geochemical Studies ◽  
The Relationship ◽  
Magnetite Formation

&lt;p&gt;Magnetite formation of serpentinized ultramafic rocks leads to variations in the magnetic properties of serpentinites; however, magnetite precipitation is still on debate.&lt;/p&gt;&lt;p&gt;In this work, we analyzed 60 cores of ultramafic rocks with a variety of serpentinization degrees. These rocks belong to the ultramafic-mafic San Juan de Otates complex in Guanajuato, Mexico. Geochemical studies have been previously conducted, enabling us to compare changes in the magnetic properties against the chemical variations generated by the serpentinization process. By studying the density and magnetic properties such as anisotropy of magnetic susceptibility, hysteresis curves as well as magnetic and temperature-dependent susceptibility and, we were able to identify the relationship between magnetic content and serpentinization degree, the predominant magnetic carrier, and to what extent the magnetite grain size depends on the serpentinization. &amp;#160;Variations in these parameters allowed us to better constrain the temperature at which serpentinization occurred, the generation of other Fe-rich phases such as Fe-brucite and/or Fe-rich serpentine as well as distinctive rock textures formed at different serpentinization degrees.&lt;/p&gt;

Structure of Moving Domain Walls in Magnetic Materials

1971 ◽  
Vol 19 (8) ◽  
pp. 274-276 ◽  
Author(s):  
Ernst Schlömann
Keyword(s):  
Magnetic Materials ◽  
Domain Walls ◽  
Moving Domain

Synthesis, Structure, and Characterization of La1−xBax (0 ≤ x ≤ 1)

1992 ◽  
Vol 271 ◽  
Author(s):  
Joseph E. Sunstrom ◽  
Susan M. Kauzlarich
Keyword(s):  
Magnetic Susceptibility ◽  
Powder Diffraction ◽  
Single Phase ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Temperature Dependent ◽  
X Ray ◽  
Early Transition Metal ◽  
Arc Melting

ABSTRACTThe compounds La1−xBaxTiO3 (0 ≤ × ≤ 1) have been prepared by arc melting stoichiometric amounts of LaTiO3 and BaTiO3. Single phase samples can be made for the entire stoichiometry range. The polycrystalline samples have been characterized by thermal gravimetric analysis, X-ray powder diffraction, and temperature dependent magnetic susceptibility. This series of compounds has been studied as a possible candidate for an early transition metal superconductor.

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