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We report the crystallographic properties of RE2NiGe3 (RE=La, Ce) synthesized by arc melting. Rietveld refinement on the powder neutron diffraction (ND) data suggest both compounds are isostructural and crystallize in the non-centrosymmetric Er2RhSi3 type structure having hexagonal space group P 6¯2c. In the crystal structure of RE2NiGe3, two dimensional arrangements of nickel and germanium atoms lead to the formation of hexagonal layers with rare earth atoms sandwiched between them. Magnetic susceptibility measurements performed in low fields exhibit antiferromagnetic ordering in cerium compound around (To=) 3.2 K. Neutron diffraction measurements at 2.8 K (i.e., at T

The neutron powder diffractometers and the polarized neutron spectrometer at the Dhruva reactor, Trombay have been used extensively for magnetic studies of several class of important materials, suc...

We report the crystallographic properties of RE2NiGe3 (RE=La, Ce) synthesized by arc melting. Rietveld refinement on the powder neutron diffraction (ND) data suggest both compounds are isostructural and crystallize in the non-centrosymmetric Er2RhSi3 type structure having hexagonal space group P 6¯2c. In the crystal structure of RE2NiGe3, two dimensional arrangements of nickel and germanium atoms lead to the formation of hexagonal layers with rare earth atoms sandwiched between them. Magnetic susceptibility measurements performed in low fields exhibit antiferromagnetic ordering in cerium compound around (To=) 3.2 K. Neutron diffraction measurements at 2.8 K (i.e., at T

Double exchange (DE)-mediated ferromagnetism in manganites, in which the Zener pair (Mn3+/Mn4+) is a key factor, is marked by the coexistence of the magnetic transition and the metal-insulator transition, thus distinguishing itself from superexchange (SE)-mediated ferromagnetism. Through detailed magnetization, transport and XAS studies, it was proposed by some of us that a unique magnetic pair-making effect occurs in Ru-substituted La0.6Pb0.4Mn1−xRuxO3 by virtue of variable valency of Ru and Mn. Ru ion, exhibiting a variable valency of Ru4+ and Ru5+, governs the DE-mediated coupling by initiating a magnetic pair-making effect with Mn3+ and Mn4+ states. Neutron diffraction measurements carried out on these compounds in the temperature range 4.2–500 K reveal the microscopic nature of magnetic ordering. Data obtained, in conjunction with data from other experimental techniques above, show that (i) Ru participates in the DE interaction with Mn for x⩽0.4, (ii) there is a weakening of DE due to depletion of Ru5+ for x>0.4, and (iii) SE ferromagnetic interactions are favored for x>0.4.

A dilute concentration of single phase Cobalt substituted Bismuth ferrite, BiFe1−XCoXO3; (x=0, 0.02) is prepared by sol-gel auto combustion method. Room temperature neutron diffraction patterns show no change in the crystal and magnetic structure upon cobalt doping. The calculation of magnetic moments shows 3.848 μB for Fe+ and 2.85 μB for Co3+. The cobalt is found to be in intermediate spin state.

Magnetic structure evolution of multiferroic hexagonal $YMn_{1-x}Fe_{x}O_{3}$ (${x} = 0, 0.05,$ and $0.1$) has been studied by carrying out detailed temperature-dependent neutron diffraction at zero- and 5T-fields. Thermodynamic data confirm antiferromagnetic ordering at $T_{N}$ in all the compositions. Our sub-$T_{N}$ neutron diffraction results assign the magnetic structure of pure $YMnO_3$ to $\Gamma_{1}$ irreducible representation. Over the perturbative-doping range, the magnetic configuration changes via $\Gamma_{1}+\Gamma_{2}$ for $YMn_{0.95}Fe_{0.05}O_{3}$ on to $\Gamma_{2}$ for $YMn_{0.9}Fe_{0.1}O_{3}$, as the maiden compositional analogue of spin-reorientation; its occurrence in temperature-domain already reported for several manganites. Moreover, while the large thermal isostructural changes observed above ${T}_{N}$ are subdued in the ordered state, small alterations by the applied 5T-field are relatively uniform across, confirming strong magneto-elastic nature of the system. Decrease of the ordered magnetic moment ($\mu_{ord}$) and planar magnetic frustration noted with Fe-doping is enhanced by the applied field, apparently through canting., Comment: 19 pages, 1 table, 9 figures, 32 (numbered) references (groups)

The compound FeMnO3 crystallizing in the mineral bixbyite structure has been prepared by mechanochemical synthesis achieved by high energy ball milling of starting compounds. The structure and magnetism have been studied using powder neutron diffraction and magnetization measurements. Magnetization measurements exhibits ferrimagnetism at 300 K and antiferromagnetic (TN) ordering around 36 K. Magnetic structure has been determined from the Rietveld analysis of the neutron diffraction pattern recorded at 300 K. Fe and Mn occupy both 8b and 24d sites in 1:1 ratio. Interaction between Fe and Mn atoms is antiferromagnetic. The ferrimagnetism arises due to anti-parallel alignment of unequal moments on 8b and 24d sites.

The magnetic structure of the quasi‐1D compound Ca3CoMnO6 (CCMO) has been determined by carrying out Rietveld analysis of low temperature neutron diffraction (ND) patterns. The magnetic measurements on CCMO have established that the compound exhibits a long range antiferromagnetic ordering (TN) around 15 K, and interesting magnetic properties below TN. In order to understand the correlation of the magnetic behavior with the magnetic structure, we have recorded ND patterns at temperatures across TN, from 2 K to 30 K and have also studied the influence of externally applied magnetic field on the magnetic ordering in CCMO. The magnetic field induces drastic changes in the pristine magnetic structure at temperatures below 15 K. We discuss here the parameters associated with magnetic structure of CCMO at low temperatures and the influence of external field on them.

Room temperature Neutron diffraction study of CoxZn1−xFe2O4 ferrite system for x = 0.3 and 0.5 synthesized using hydrothermal techniques is reported here. The results show that the system x = 0.3 exhibits magnetic moment 1.1 Bohr magneton while x = 05 sample exhibits 1.9 Bohr magneton at room temperature. These values agree well with magnetization measurements.

We have studied the effect of Dy doping on the crystal structure and magnetic properties in hexagonal YMnO3. Dy was substituted at Y site up to x = 0.20. Polycrystalline Y1−xDyxMnO3 (x = 0, 0.02, 0.05, 0.10, 0.15, and 0.20) were synthesized by solid state reaction method. Room temperature neutron diffraction (ND) provides evidence for no change in crystal structure but lattice parameters gets modify with respect to doping, low temperature magnetization measurements shows modification in Curie‐Weiss temperature and Neel temperature. These results are understood in terms of variation in frustration parameter due to Dy induced strain in Y plane of hexagonal YMnO3.

We have investigated the effects of substituting Dy with Y on the magneto‐elastic coupling in YMnO3 using neutron diffraction (ND), dielectric, and specific heat measurements. Polycrystalline Y1−xDyxMnO3 (x = 0, 0.05) was synthesized by solid state reaction method. Extensive ND measurements provide evidence for change in the lattice parameters, and ordered magnetic moment as a function of temperature. Dielectric results show that due to Dy doping, inverse S‐shape anomaly shifts to the lower temperature side which is also indicated by specific heat measurements. These results are understood in terms of modification in magnetoelastic coupling triggered by Dy induced strain in Y plane of YMnO3.We have investigated the effects of substituting Dy with Y on the magneto‐elastic coupling in YMnO3 using neutron diffraction (ND), dielectric, and specific heat measurements. Polycrystalline Y1−xDyxMnO3 (x = 0, 0.05) was synthesized by solid state reaction method. Extensive ND measurements provide evidence for change in the lattice parameters, and ordered magnetic moment as a function of temperature. Dielectric results show that due to Dy doping, inverse S‐shape anomaly shifts to the lower temperature side which is also indicated by specific heat measurements. These results are understood in terms of modification in magnetoelastic coupling triggered by Dy induced strain in Y plane of YMnO3.

The interplay between ferromagnetism and charge-ordering in a manganite system, achieved by means of Ru substitution at Mn-site in a charge-ordered Bi0.4Ca0.6MnO3 system, has been investigated by using magnetization and neutron diffraction (ND) studies. ND experiments were carried out on polycrystalline samples of Bi0.4Ca0.6Mn1 − xRu x O3 (x = 0.1 and 0.2) as a function of temperature and also in presence of a magnetic field. The magnetic structure determined from the Rietveld refinement of ND data has been compared and discussed with the magnetization measurements. The magnetic properties observed from the ND measurements agree well with the magnetization measurements, giving more insight into the magnetism of these compounds.

Binary intermetallic compound Nd7Rh3, crystallizes in a Th7Fe3 type hexagonal structure in space group P63mc and has been reported to show two antiferromagnetic (AFM) phase transitions at 32 K and 10 K from magnetic susceptibility, and a field induced first-order magnetic transition at a field strength of 1 Tesla at 2 K from magnetization measurements. These magnetic properties are different from the isostructural counterparts like Tb7Rh3, Ho7Rh3, and Nd7Ni3. In order to understand the differences in the magnetic behaviour between Nd7Rh3 and other isostructural compounds, we have carried out neutron diffraction (ND) studies on polycrystalline Nd7Rh3, at various temperatures between 2 and 45 K. ND patterns were also recorded at T = 2K in the presence of applied magnetic fields from 0 to 1.5 Tesla. ND spectra on Nd7Ni3 and Ho7Rh3, for example, at 2 K in zero magnetic field exhibit a strong AFM peak at a Q ( = 4?Sin?/?) value of 0.32 and 0.38 ??1, respectively. However, ND spectra on Nd7Rh3, carried out at Focusing Crystal Diffractometer (FCD-Dhruva-Mumbai), diffractometers E6 and E9 (HZB-Berlin) using wavelengths ? = 1.48?, 2.45? and 2.8? respectively, at T = 2K in zero field do not exhibit any AFM peaks in the entire Q-range studied. Instead, long-range ferromagnetic order is established as evidenced by the intensity enhancement of the nuclear Bragg peaks. The lack of extra peaks in the ND patterns would imply that the magnetic order seen in magnetization could be of a k = 0 type which changes from one type to another on the application of magnetic field. The results of nuclear and magnetic structure refinement are discussed to explain the magnetic behaviour of Nd7Rh3, at low temperatures.