Fit Of Curie-Weiss Law Research Articles

Magnetic Studies of Iron-Doped Probable Weyl Semimetal WTe2

The non-trivial topology of electronic bands in Weyl semimetals originates from band inversion due to strong spin–orbit coupling. The Weyl semimetals have pairs of Weyl gap-less nodes in the bulk Brillouin zone. The tungsten ditelluride WTe2 likely belongs to type II Weyl semimetals. Doping WTe2 with magnetic ions could induce magnetic ordering in this crystal, which provides prospects for practical applications. We studied the magnetic properties of the iron-doped single crystals Fe0.03W0.97Te2, annealed and unannealed, in comparison with the undoped WTe2. Measurements of the dc magnetization were carried out from 1.8 to 400 K. We revealed pronounced ferromagnetic ordering that was affected by annealing. Anomalies associated with antiferromagnetism and paramagnetism were also found. The magnetic order was suppressed by a field of 60 kOe. The rise in susceptibility with increasing temperature was observed at high temperatures in all samples and was treated using a model developed for Weyl semimetals. The Curie–Weiss law fit at 60 kOe showed that the effective magnetic moment was close to that of Fe2+. Metamagnetism was demonstrated for the unannealed doped WTe2 crystal. The data for the heat capacity of the iron-doped sample agreed with results for the undoped WTe2.

Composition design of PMN-PH-PT piezoelectric ceramics for high-temperature actuator applications

High-Curie temperature (Tm) piezoelectric ceramics 0.15Pb(Mg1/3Nb2/3)O3-xPbHfO3-(0.85-x)PbTiO3 (0.15PMN-xPH-(0.85-x)PT, x = 0.36, 0.38, 0.39, 0.40, 0.42, 0.15PMN-PH-PT) were synthesized by the solid-state reaction method via the columbite precursor route. The synthesized 0.15PMN-PH-PT ceramics exhibit pure perovskite structure with compositions locate near the morphotropic phase boundary (MPB), where the rhombohedral phase and the tetragonal phase coexist. The sintered samples present high densification, in which the 0.15Pb(Mg1/3Nb2/3)O3-0.38PbHfO3-0.47PbTiO3 (0.15PMN-0.38PH-0.47PT) ceramics present the highest relative density, being 97.76%. The dielectric performance-temperature curves measured at different frequencies, the Curie-Weiss law fitting and the quadratic law fitting indicate that the ferroelectric phase transition from ferroelectric phase to paraelectric phase occurred at T0 in the 0.15PMN-PH-PT ceramics is driven by the displacive phase transition, and the 0.15PMN-PH-PT ceramics belong to normal ferroelectrics with diffused phase transition characteristic. Due to the MPB effect and high relative density, the 0.15PMN-0.38PH-0.47PT ceramics exhibit the best integral electrical properties, excellent thermal stability and large electric field induced strain, which present prospect promising for actuator applications under elevated environmental temperatures.

Magnetic Behaviors of Ca2FeMoO6 without Double Mixture Gas Protection under Heat Treatment

The Ca2FeMoO6 ceramics powder were prepared by solid state reaction involving compression and high temperature calcine. The magnetic properties arise from the environments of the Fe 3+ and Mo 5+ oxidation states which can be modified, with heat treatment at 800 °C and different dwell times exhibited the largest hysteresis loop at 50 K. In addition, the CFMO powder at the high temperature of 800 °C for 10 hours exhibited a high Ms~1.494 emu/g at 50 K and ~0.601emu/g at room temperature. Using the Curie-Weiss law fitting to determine μeff~28.121μB high spin of Fe and Mo, and a negative θ indicates antiferromagnetic characteristics of the CFMO sample.

Targeted Synthesis of Uranium(IV) Thiosilicates.

Two new uranium(IV) thiosilicates, Cs2Na4[U2(SiS4)2(Si2S8)] and Cs2.12Na3.88[U2(SiS4)2(Si2S7)], were obtained by flux crystal growth using SiS2 as a silicon source. The former compound contains a novel Si2S86- unit that features a terminal persulfide group. The magnetic susceptibility measurements performed on this compound revealed paramagnetic behavior with a moment of 3.49 μB per uranium atom as obtained from a Curie-Weiss law fit and showed no magnetic transition down to 2 K. The structures are based on closely related isomeric planar and 3D topologies that can be transformed into one another by a rotation of the structural units.

Study, Magnetic Properties of BaTiFeO<sub>3</sub> Perovskite Prepared by Solid State Method

The magnetic properties of BaFeTiO3 (BTFO) perovskite are investigated. BTFO samples were prepared by solid state reaction method through compression. Magnetic properties are influenced by electron environments of the Fe3+ ions within the perovskite structure. Furthermore, the values of Ms and Mr indicate ferromagnetic behaviour in BFMO ceramics sintered at 800 oC for sintering as 800 oC for 6 hours at 1.898 emu/g, which is magnetization strength material more than sintering at 4 hours, 8 hours, 10 hours as 1.794 emu/g, 1.333 emu/g and 1.192 emu/g at measured of low temperature. Using the Curie-Weiss law fitting for investigate μeff~38μB high spin of Fe, negative of θ present to antiferromagnetic characteristics of BTFO sample. Finally, BTFO sintering at the high temperature of 800 oC for 6 hours exhibited the high Ms~1.898 emu/g at 50 K and ~1.216emu/g at room temperature.

Characterization of Antiferromagnetism in Double Perovskites Ba<sub>2</sub>FeMoO<sub>6</sub> Prepared by Solid State Method

The magnetic properties of Ba2FeMoO6 (BFMO) double perovskite are investigated. BFMO samples were prepared by solid state reaction method through compression. Magnetic properties are influenced by electron environments of the Fe3+ and Mo5+ ions within the perovskite structure. BFMO sintered at 800 oC exhibited the largest hysteresis loop at 50 K. In addition, the values of Ms and Mr indicate ferromagnetic behaviour in BFMO ceramics sintered at 800 oC for different times up to 10 hours. Using the Curie-Weiss law fitting to investigate μeff~30μB high spin of Fe and Mo, and negative θ present the antiferromagnetic characteristics of the BFMO sample.

Ferroelectric transition in compressively strained SrTiO3 thin films

We report the temperature dependent capacitance-voltage characteristics of Pt/SrTiO3 Schottky diodes fabricated using compressively strained SrTiO3 thin films grown on (LaAlO3)0.3(Sr2AlTaO6)0.7 (LSAT) substrates. The measurements reveal a divergence of the out of plane dielectric constant of SrTiO3 peaked at ∼140 K, implying a ferroelectric transition. A Curie-Weiss law fit to the zero-bias dielectric constant suggests a Curie temperature of ∼56 K. This observation provides experimental confirmation of the theoretical prediction of out of plane ferroelectricity in compressively strained SrTiO3 thin films grown on LSAT substrate. We also discuss the roles of the field-dependent dielectric constant and the interfacial layer in SrTiO3 on the extraction of the Curie temperature.

Magnetic properties of NiO (nickel oxide) nanoparticles: Blocking temperature and Neel temperature

Crystalline nickel oxide (NiO) nanoparticles dispersed in an amorphous silica matrix have been prepared by a sol–gel combustion synthesis method. The sample was characterized using X-ray powder diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy and superconducting quantum interference device magnetometry. The nanoparticles were spherical with an average size of about 5 nm and narrow particle size distribution. The magnetization measurements revealed two maxima in the zero-field cooled magnetization curve at 5 K and 56 K. An analysis of DC and AC magnetic susceptibility measurements revealed that the higher temperature maximum corresponded to the onset of antiferromagnetic ordering within the particles. The Néel temperature of TN = 56 K is much lower than in bulk NiO. The 5 K maximum corresponded to the particle blocking temperature TB. The frequency dependence of TB was successfully fitted using the Vogel–Fulcher law, indicating the presence of weak inter-particle interactions (C1 = 0.08 and C2 = 0.76). A Curie–Weiss law fit to the magnetic susceptibility above TN revealed antiferromagnetic exchange interactions with a Curie–Weiss temperature of θ = 24 K and an effective magnetic moment of μeff = 2.87 μB per NiO unit. We conclude that these magnetic properties can be attributed to the smallness of the NiO nanoparticles and to crystal lattice defects.

Ferroelectric Transition and Curie—Weiss Behavior in Some Filled Tungsten Bronze Ceramics

Ferroelectric transitions in filled tungsten bronze ceramics Sr4R2Ti4Nb6O30, Sr5RTi3Nb7O30 (R=La, Nb, Sm & Eu) and Ba4Nd2Ti4Nb6O30 are investigated with differential scanning calorimetry (DSC) and the Curie—Weiss law fitting to the dielectric constant. The magnitude of the Curie-Weiss constant C ∼ 105 suggests displacement-type ferroelectric transition in the present compounds. The large ΔT difference between dielectric maximum temperature Tm and Curie—Weiss temperature T0) values indicate the difficult formation of ferroelectric domains or polar nanoregions in the present compounds and also the characteristics of the first order ferroelectric transition. Three categories are suggested for the ferroelectric transition in the above tungsten bronzes. The ferroelectric transition exhibits large thermal hysteresis. According to the DSC results, gradual recovery of the endothermic peak occurs after aging at temperature below the Curie point, indicating the gradual stability of the ferroelectric phase after cooling from the high-temperature para-electric phase. The relationship between the Curie—Weiss law fitting parameters and the nature of the ferroelectric transition is modified for the filled tungsten bronzes.

Dielectric and electro-optical response of a room temperature tri-component antiferroelectric mixture

Frequency- and temperature-dependent dielectric and switching parameters of a room temperature tri-component antiferroelectric liquid crystal mixture W-287 have been determined. Dielectric, optical texture and thermodynamic studies show wide room temperature range antiferroelectric SmC*a (˜91.1°C to <–25°C) phase in addition to high temperature paraelectric SmA* (˜2.6°C) and ferroelectric SmC* (˜4.4°C) phases. The dielectric studies carried out in the frequency range of 1–35 MHz under planar anchoring condition of the molecules show five different relaxation modes appearing in the SmA*, SmC* and SmC*a phases. Using Curie–Weiss law fit, ferroelectric SmC* to paraelectric SmA* transition temperature has been found to be 91.8°C. The dielectric response of SmC*a phase exhibits unusually three relaxation modes due to collective as well as individual molecular processes in addition to phason mode in the SmC* phase and amplitudon mode in the SmA* phase. Spontaneous polarisation, switching time and rotational viscosity have also been determined. The maximum value of PS is ˜300 nC/cm2, whereas viscosity is moderate. Switching time is of the order of few milli seconds.

Synthesis Process and Magnetic Characterization of the Novel Aurivillius Ferroelectric Material ${\hbox{Bi}}_{4}{\hbox{Gd}}_{2}{\hbox{Ti}}_{3}{\hbox{Fe}}_{2}{\hbox{O}}_{18}$

Comprehensive research of the synthesis process by high temperature solid-state reaction method, the crystal structure characterization, and the magnetic properties of the Aurivillius type Bi-layered perovskite-like structure <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\hbox{Bi}}_{4}{\hbox{Gd}}_{2}{\hbox{Ti}}_{3}{\hbox{Fe}}_{2}{\hbox{O}}_{18}$</tex> </formula> was undertaken. Patterns of X-ray diffraction measurements and Rietveld analysis allow us to establish that this material crystallizes in a pseudo-orthorhombic structure which belongs to the I2cm (#46) space group. The crystal structure is characterized by <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\hbox{Bi}}_{2}{\hbox{O}}_{2}$</tex></formula> layers and complex perovskite-like structures, with quintuplets octahedra <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">${\hbox{TiO}}_{6}$</tex></formula> , and the Bi-cations occupying the A-site. The unit-cell parameters are given by <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$a=5.5234(2)\ \hbox{\rm{\AA}}$</tex></formula> , <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$b=5.5312(2)\ \hbox{\rm{\AA}}$</tex> </formula> , and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$c=52.5642(2)\ \hbox{\rm{\AA}}$</tex></formula> , the angles are <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\alpha=\beta=\gamma=90.0^{\circ}$</tex></formula> , and unit-cell volume <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm V}=1605.9(1)\ \hbox{\rm{\AA}}^{3}$</tex></formula> . Magnetic properties found from the fit of Curie-Weiss law to the curves of magnetic susceptibility <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\chi$</tex></formula> as a function of temperature show that the Bi-layered Aurivillius material <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\hbox{Bi}}_{4}{\hbox{Gd}}_{2}{\hbox{Ti}}_{3}{\hbox{Fe}}_{2}{\hbox{O}}_{18}$</tex> </formula> behaves as a paramagnetic material with evidence of ferromagnetic contributions, and allows for determining the Curie constant, given by <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm C}=0.014\ {\hbox{emuK/mol}}$</tex> </formula> , effective magnetic moment of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$P_{\rm eff}\mu_{B}=7.78\mu_{\rm B}$</tex></formula> , and temperature independent susceptibility <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\chi_{o}=0.0064\ {\hbox{emu/mol}}$</tex></formula> . Field dependence of magnetization proves strongly paramagnetic behavior of the Bi-layered <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">${\hbox{Bi}}_{4}{\hbox{Gd}}_{2}{\hbox{Ti}}_{3}{\hbox{Fe}}_{2}{\hbox{O}}_{18}$</tex> </formula> .

Ferromagnetism and Bound Magnetic Polaron Behavior in ${(\hbox{In}_{1-{\rm x}}\hbox{Co}_{\rm x})}_{2}\hbox{O}_{3}$

Bulk samples of (In1-xCox)2O3 were prepared in single phase form for x=0.02 and 0.07 . The samples are found to be free from impurities such as Co3O4 and other cobalt oxides as per the detailed micro structural and Raman spectroscopic analysis. Temperature variation of magnetization upto 900 K for 0.3 T magnetic field and field variation of magnetization at different temperatures down to 20 K were measured. Both the samples are found to exhibit clear room temperature ferromagnetism. The increase in spontaneous magnetization, remanent magnetization and coercive field with decrease in temperature is explained in terms of magnetic anisotropy. The initial magnetization data could be fitted to the bound magnetic polaron model. A clear paramagnetic to ferromagnetic transition with TC ≈ 718 K was observed. The Curie-Weiss law fit conform the ferromagnetic transition with effective magnetic moment value of 1.5 μB.

Magnetic properties of Nd1−xAgxMnO3 compounds

Polycrystalline Nd1−xAgxMnO3 compounds were prepared in single-phase form up to 20% of Ag doping. They are found to crystallize inthe Pbnm space group with an increase in lattice parameters with doping. The magnetic propertieswere studied by measuring dc magnetization and ac susceptibility. A paramagnetic toferromagnetic transition along with the signature of the presence of competingantiferromagnetic interaction has been observed. The saturation magnetic moment up to2.2 μB per formula unit has been observed at 78 K. The measured magnetization hasbeen analyzed by using the Brillouin function and by taking into account theferromagnetic interaction. The measured magnetization has been explained onthe basis of spin canting with a ferromagnetic component along a unique axisand with an antiferromagnetic interaction in a plane perpendicular to the axis.The average magnetic moment estimated from the Curie–Weiss law fit in theparamagnetic region is comparable to the theoretical magnetic moment due toMn3+/Mn4+ and Nd3+ ions. The analyses of frequency variation of ac susceptibility and harmonic susceptibilityindicate the presence of spin-glass-like behavior below the ferromagnetic transitiontemperature.

Synthesis and study of the structural characteristics of a new complex perovskite oxide Sr 2HoHfO 5.5 for its use as a substrate for YBCO superconducting films

A new complex cubic perovskite oxide Sr 2HoHfO 5.5 has been prepared by solid state reaction process. X-ray diffraction studies show that Sr 2HoHfO 5.5 has a A 2BB ′O 6 type complex cubic perovskite structure and presence of the significant intensities of superstructure reflections in the X-ray spectrum reveal that it is an ordered complex cubic perovskite oxide. The experimental value of the lattice parameter of Sr 2HoHfO 5.5, is a=8.1725 Å. Based on the doubling of primitive ABO 3 cubic perovskite unit cell, (1/2) a=4.0862 Å of Sr 2HoHfO 5.5 is comparable to the lattice parameter a=3.8227 Å of YBCO superconductor. Sr 2HoHfO 5.5 has good lattice matching (lattice mismatch ∼6%) with YBCO superconductor. The dc magnetic susceptibility of Sr 2HoHfO 5.5, measured in the temperature range 5–300 K shows a Curie–Weiss behavior. Using a Curie–Weiss law fitting we obtain a effective magnetic moment per Ho 3+ ion in Sr 2HoHfO 5.5 of 9.76 μ B. This value is slightly lower than the spin-only moment (10.60 μ B) expected for an isolated Ho 3+ ion.

Magnetic Properties of 8H-Type Hexagonal Ba(Na1/4Ru3/4)O3

Abstract The magnetic properties of 8H-type hexagonal-type Ba(Na1/4Ru3/4)O3 having a 2D geometry of Ru5+(t2g3) ions were studied by magnetic-susceptibility measurements in the temperature range 5 K &amp;lt; T &amp;lt; 700 K. In this structure, the face-shared RuO6 octahedra form (Ru2O9)8− clusters with a 2D array, which are sandwiched by 2D layers of the NaO6 and the RuO6 corner-shared octahedra. The magnetic data show an antiferromagnetism-like behavior, and could be well fitted to a Curie-Weiss law above 520 K with μeff = 3.74 μB and θ = −1330 K. At a lower temperature range of 262 K &amp;lt; T &amp;lt; 520 K, it showed a reduced magnetic moment of μeff = 2.32 μB and θ = −221 K by a new Curie–Weiss law fit. The χ(T) behavior showed a strong external field dependence below 262 K, and magnetic anomaly peaks could be observed in low-field FC data at 30, 110, and 180 K, respectively. The magnetic properties of Ba(Na1/4Ru3/4)O3 are discussed concerning both a long-range 3D antiferromagnetic order and a spin-glass-like behavior.

Structural and magnetic properties of the complex perovskite oxideBa2HoHfO5.5

The complex cubic perovskite oxide ${\mathrm{Ba}}_{2}{\mathrm{HoHfO}}_{5.5}$ in the Ho-Ba-Hf-O rare-earth based oxide system has been prepared by a solid-state reaction process. Powder x-ray-diffraction studies show that ${\mathrm{Ba}}_{2}{\mathrm{HoHfO}}_{5.5}$ has an ${A}_{2}{\mathrm{BB}}^{\ensuremath{'}}{\mathrm{O}}_{6}$ complex cubic perovskite structure. The x-ray-diffraction spectrum of single-phase ${\mathrm{Ba}}_{2}{\mathrm{HoHfO}}_{5.5}$ consists of strong peaks characteristics of a primitive cubic $\mathrm{AB}{\mathrm{O}}_{3}$ perovskite plus a few weak reflection lines arising from the superlattice. The presence of significant intensities of superstructure reflections in the x-ray spectrum of ${\mathrm{Ba}}_{2}{\mathrm{HoHfO}}_{5.5}$ acts as a signature for an ordered complex cubic perovskite oxide. Based on the doubling of primitive $\mathrm{AB}{\mathrm{O}}_{3}$ cubic perovskite unit cells, the lattice parameter of ${\mathrm{Ba}}_{2}{\mathrm{HoHfO}}_{5.5}$ calculated from the experimental x-ray diffraction is $a=8.316$ \AA{}. The real part of the ac magnetic susceptibility of ${\mathrm{Ba}}_{2}{\mathrm{HoHfO}}_{5.5},$ measured in the temperature range 5 to 300 K shows a Curie-Weiss behavior. Using a Curie-Weiss law fitting we obtain an effective magnetic moment per ${\mathrm{Ho}}^{3+}$ ion in ${\mathrm{Ba}}_{2}{\mathrm{HoHfO}}_{5.5}$ of $9.33{\ensuremath{\mu}}_{B}.$ This value is approximately 10% less than the spin-only moment $(10.60{\ensuremath{\mu}}_{B})$ expected for an isolated Ho ion.

Magnetic properties of (CH3NH3) 2CoX4 (X=Cl,Br) single crystals

The DC magnetic susceptibility χ of (CH3NH3) 2CoX4 (X = Cl and Br) single crystals were measured between 1.2 K and 300 K. The χ parallel and perpendicular to c-axis showed no anomalous behavior in the whole temperature range. The positive exchange integral and negative anisotropy constant, derived from the Curie-Weiss law fitting to the χ data, mean that these cobalt compounds can be treated as 2D-XY-ferromagnets.

Crystal structure and magnetism in CoSb 2O 6 and CoTa 2O 6

CoSb 2O 6 was investigated by neutron diffraction and magnetic susceptibility techniques. The structure found was tetragonal, of the trirutile type, with space group P4 2 mnm , a = 4.6495(2) Å, c = 9.2763(6)Å. Low-temperature neutron data gave no evidence of structural change down to 20 K. Susceptibility data showed a deviation from Curie-Weiss behavior below 100 K and a maximum at 35 K associated with low-dimensional ordering. A Curie-Weiss law fit of the data above 100 K gave μ eff = 4.62(1) μ B and θ = −32.4(3) K. The ordered magnetic structure as determined by neutron diffraction was indexed on a supercell (2 a, a, 2 c) and is similar to that found previously for FeTa 2O 6. Measured magnetic moments below T c gave an extrapolated zero-temperature moment of 3.3(2) μ B for Co 2+ and critical parameters β = 0.12(2) and T c = 12.64(5) K, consistent with the two-dimensional Ising model. The crystal structure of CoTa 2O 6 was found to be the same as that for CoSb 2O 6 with a = 4.7358(3)Å and c = 9.1708(7)Å and with no structural change down to 10 K. At 4.2 K magnetic reflections were observed that could be indexed with a propagation vector k 0 = ( 1 4 , 1 4 , 1 4 ). A two-cone axis helical spin structure is proposed which can account for the observed intensities. Some of the differences in magnetic properties of the two compounds can be understood in terms of bond distances within the CoO layers.

Crystal structure and magnetism in MnSb 2O 6: Incommensurate long-range order

MnSb 2O 6 was investigated by neutron diffraction and magnetic susceptibility techniques. The structure was trigonal, space group P321, a = 8.8011(3) Å, c = 4.7241(1)Å. Low-temperature neutron data gave no evidence of structural change down to 14 K. Inverse susceptibility data show a deviation from Curie-Weiss behavior below 200 K and the magnetization shows a maximum at 12 K associated with the onset of three-dimensional order. A Curie-Weiss law fit of the susceptibility data above 200 K gave an Mn 2+ moment of 5.76(1) μ B. The ordered magnetic structure as determined by neutron diffraction was incommensurate with the nuclear lattice and could be described by a propagation vector τ = (0.013, 0.013, 0.179) in reciprocal lattice units. Measured magnetic moments below T c gave an extrapolated zero point moment of 4.6 μ B for Mn 2+ and critical parameters β = 0.31(2) and T c = 11.92(5) K.