Showing papers on "Magnetic structure published in 2008"
TL;DR: The role of magnetism in the superconductivity that occurs when mobile 'electrons' or 'holes' are doped into the antiferromagnetic parent compounds of rare-earth iron-based oxide systems was investigated in this paper.
Abstract: Following the discovery of long-range antiferromagnetic order in the parent compounds of high-transition-temperature (high-T(c)) copper oxides, there have been efforts to understand the role of magnetism in the superconductivity that occurs when mobile 'electrons' or 'holes' are doped into the antiferromagnetic parent compounds. Superconductivity in the newly discovered rare-earth iron-based oxide systems ROFeAs (R, rare-earth metal) also arises from either electron or hole doping of their non-superconducting parent compounds. The parent material LaOFeAs is metallic but shows anomalies near 150 K in both resistivity and d.c. magnetic susceptibility. Although optical conductivity and theoretical calculations suggest that LaOFeAs exhibits a spin-density-wave (SDW) instability that is suppressed by doping with electrons to induce superconductivity, there has been no direct evidence of SDW order. Here we report neutron-scattering experiments that demonstrate that LaOFeAs undergoes an abrupt structural distortion below 155 K, changing the symmetry from tetragonal (space group P4/nmm) to monoclinic (space group P112/n) at low temperatures, and then, at approximately 137 K, develops long-range SDW-type antiferromagnetic order with a small moment but simple magnetic structure. Doping the system with fluorine suppresses both the magnetic order and the structural distortion in favour of superconductivity. Therefore, like high-T(c) copper oxides, the superconducting regime in these iron-based materials occurs in close proximity to a long-range-ordered antiferromagnetic ground state.
1,441 citations
TL;DR: Graphene-nanoribbon edges are determined as a function of the hydrogen content of the environment by means of density functional theory and the existence of exotic edge electronic states and/or magnetism is rationalized in terms of simple concepts from organic chemistry.
Abstract: We determine the stability, the geometry, the electronic, and magnetic structure of hydrogen-terminated graphene-nanoribbon edges as a function of the hydrogen content of the environment by means of density functional theory. Antiferromagnetic zigzag ribbons are stable only at extremely low ultravacuum pressures. Under more standard conditions, the most stable structures are the mono- and dihydrogenated armchair edges and a zigzag edge reconstruction with one di- and two monohydrogenated sites. At high hydrogen concentration "bulk" graphene is not stable and spontaneously breaks to form ribbons, in analogy to the spontaneous breaking of graphene into small-width nanoribbons observed experimentally in solution. The stability and the existence of exotic edge electronic states and/or magnetism is rationalized in terms of simple concepts from organic chemistry (Clar's rule).
518 citations
TL;DR: In this paper, the effect of heterovalent Ca, Sr, Pb, and Ba substitution on the crystal structure, dielectric, local ferroelectric, and magnetic properties of the BiFeO3 multiferroic perovskite was studied.
Abstract: In this work, we studied the effect of heterovalent Ca, Sr, Pb, and Ba substitution on the crystal structure, dielectric, local ferroelectric, and magnetic properties of the BiFeO3 multiferroic perovskite. Ceramic solid solutions with the general formula Bi0.7A0.3FeO3 (A is a doping element) were prepared and characterized by x-ray diffraction, dielectric, piezoresponse force microscopy (PFM), and magnetic measurements. It is shown that the crystal structure of the compounds is described within the space group R3c, permitting the spontaneous polarization, whose existence was confirmed by the PFM data. Magnetic properties of the solid solutions are determined by the ionic radius of the substituting element. Experimental results suggest that the increase in the radius of the A-site ion leads to the effective suppression of the spiral spin structure of BiFeO3, resulting in the appearance of net magnetization.
312 citations
TL;DR: The spin-1/2 antiferromagnetic Heisenberg model on the kagome lattice is numerically studied using the density-matrix renormalization group method and is found to be a magnetically disordered spin liquid, characterized by an exponential decay of spin-spin correlation function in real space and a magnetic structure factor showing system-size independent peaks at commensurate magnetic wave vectors.
Abstract: We numerically study the spin-$\frac{1}{2}$ antiferromagnetic Heisenberg model on the kagome lattice using the density-matrix renormalization group method. We find that the ground state is a magnetically disordered spin liquid, characterized by an exponential decay of spin-spin correlation function in real space and a magnetic structure factor showing system-size independent peaks at commensurate magnetic wave vectors. We obtain a spin triplet excitation gap $\ensuremath{\Delta}E(S=1)=0.055\ifmmode\pm\else\textpm\fi{}0.005$ by extrapolation based on the large size results, and confirm the presence of gapless singlet excitations. The physical nature of such an exotic spin liquid is also discussed.
162 citations
TL;DR: The measurements show the existence of two transitions to long-range ordered ferrimagnetic states, the first collinear and the second noncollinear, and taken together, the crystal and magnetic structures indicate a staggered ordering of the V d orbitals.
Abstract: Neutron inelastic scattering and diffraction techniques have been used to study the MnV2O4 spinel system. Our measurements show the existence of two transitions to long-range ordered ferrimagnetic states, the first collinear and the second noncollinear. The lower temperature transition, characterized by development of antiferromagnetic components in the basal plane, is accompanied by a tetragonal distortion and the appearance of a gap in the magnetic excitation spectrum. The low-temperature noncollinear magnetic structure has been definitively resolved. Taken together, the crystal and magnetic structures indicate a staggered ordering of the V d orbitals. The anisotropy gap is a consequence of unquenched V orbital angular momentum.
115 citations
TL;DR: In this paper, the magnetic and ferroelectric properties of multiferroic RMn2O5 (R = Y, Tb, Ho, Er, Tm) are reviewed based on recent neutron diffraction and dielectric measurements.
Abstract: The magnetic and ferroelectric properties of multiferroic RMn2O5 (R = Y, Tb, Ho, Er, Tm) are reviewed based on recent neutron diffraction and dielectric measurements. Successive phase transitions of magnetic and dielectric ordering were found to occur simultaneously in this system. The characteristic magnetic ordering of the system exhibits an incommensurate–commensurate phase transition, and again transitions to an incommensurate phase. Special attention is given to the magnetic structure in order to discuss the mechanism for the introduction of ferroelectric polarization. For all the compounds examined, the spin configuration for Mn4+ and Mn3+ ions in the commensurate magnetic phase, where spontaneous electric polarization occurs, was determined to be a transverse spiral spin structure propagating along the c-axis. By contrast, the alignment of the induced 4f moment of R3+ ions showed variation, depending on the character of each of the elements. Corresponding responses to external fields such as a magnetic field, hydrostatic pressure etc at low temperature are strongly dependent on the rare earth element present in the RMn2O5 system. The so-called colossal magnetoelectric effect in this system can be easily interpreted by the phase transition from the magnetic incommensurate and weak ferroelectric phase to the commensurate and ferroelectric phase.
110 citations
TL;DR: In this paper, single crystals of multiferroic BiFeO3 were investigated using neutron scattering, and the application of an electric field reversibly switches ferroelastic domains, inducing changes in the magnetic structure which follows rotation of the structural domains.
Abstract: Single crystals of multiferroic BiFeO3 were investigated using neutron scattering. Application of an electric field reversibly switches ferroelastic domains, inducing changes in the magnetic structure which follows rotation of the structural domains. In addition, electric fields can be used to control the populations of the equivalent magnetic domains within a single ferroelastic domain, possibly via field-induced strain.
110 citations
TL;DR: The structure and magnetic properties of 3 and 5 mol% (based on the starting concentrations) Co- and Mn-doped ZnO nanorods, synthesized by a straightforward and experimentally simple nonaqueous sol-gel route based on benzyl alcohol as solvent, have been investigated by various characterization techniques, including X-ray diffraction with Rietveld refinement, high-resolution transmission electron microscopy, selected area electron diffraction, energy dispersive Xray spectroscopy, magnetization measurements and electron paramagnetic resonance as mentioned in this paper.
Abstract: The structure and the magnetic properties of 3 and 5 mol% (based on the starting concentrations) Co- and Mn-doped ZnO nanorods, synthesized by a straightforward and experimentally simple nonaqueous sol–gel route based on benzyl alcohol as solvent, have been investigated by various characterization techniques, including X-ray diffraction with Rietveld refinement, high-resolution transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectroscopy, magnetization measurements and electron paramagnetic resonance. The doped as-synthesized ZnO nanocrystals retain the wurtzite structure with a morphology in the form of nanorods grown along the [001] direction, whose dimensional parameters as well as degree of agglomeration depend on the type and level of doping. The Co-doped ZnO powders are ferromagnetic with a Curie temperature exceeding room temperature. Conversely, the Mn-doped samples show antiferromagnetic correlations with a possible transition to an antiferromagnetic ground state below TN = 10 K. The results suggest that the magnetic ground state is extremely sensitive to the type of dopant, which is in agreement with previous studies.
108 citations
TL;DR: It is shown that the magnetic interactions in LuFe(2)O(4) are three-dimensional in character, and the magnetic structure is refined as a ferrimagnetic spin configuration below the 240 K transition.
Abstract: We present single crystal neutron diffraction measurements on multiferroic LuFe{sub 2}O{sub 4}. Magnetic reflections are observed below transitions at 240 and 175 K indicating that the magnetic interactions in LuFe{sub 2}O{sub 4} are three-dimensional in character. The magnetic structure is refined as a ferrimagnetic spin configuration below the 240 K transition. Below 175 K a significant broadening of the magnetic peaks is observed along with the buildup of a diffuse component to the magnetic scattering.
107 citations
TL;DR: In this article, the magnetic structure consists of chains of parallel spins that are arranged antiparallel between chains, which is the same in-plane spin arrangement as observed in all the other iron oxypnictide materials.
Abstract: Polarized and unpolarized neutron-diffraction measurements have been carried out to investigate the iron magnetic order in undoped NdFeAsO. Antiferromagnetic order is observed below 141(6) K, which is in close proximity to the structural distortion observed in this material. The magnetic structure consists of chains of parallel spins that are arranged antiparallel between chains, which is the same in-plane spin arrangement as observed in all the other iron oxypnictide materials. Nearest-neighbor spins along the $c$ axis are antiparallel like LaFeAsO. The ordered moment is $0.25(7)\phantom{\rule{0.2em}{0ex}}{\ensuremath{\mu}}_{B}$, which is the smallest moment found so far in these systems.
102 citations
TL;DR: In this article, the authors proposed to fabricate heterostructures formed by piezoelectric materials and magnetic antiperovskites as magnetoelectrics, which can be controlled by a small applied biaxial strain.
Abstract: Recent experimental and theoretical studies of the magnetoelectric (ME) effect in the nanocomposite structures and in laminates show an enhanced ME coefficient. These materials combine piezoelectric properties of the paramagnetic phase and piezomagnetic properties of the magnetic phase. We propose to fabricate heterostructures formed by piezoelectric materials and magnetic antiperovskites as magnetoelectric materials. We show that the magnetic structure of antiperovskite, such as ${\mathrm{Mn}}_{3}\mathrm{Ga}\mathrm{N}$, can be controlled by a small applied biaxial strain. The lowering of symmetry with the strain causes the local magnetic moments of Mn atoms to rotate from the trigonal ${\ensuremath{\Gamma}}^{5g}$ structure with symmetric curl of spin density in the (111) plane to a monoclinic symmetry structure. As a result, an appreciable net magnetization appears in the strained system.
TL;DR: The magnetic properties of RMn2O5 multiferroics as obtained by unpolarized and polarized neutron diffraction experiments are reviewed in this article, where qualitative features of the magnetic phase diagram in both zero magnetic field and in field are discussed.
Abstract: The magnetic properties of RMn2O5 multiferroics as obtained by unpolarized and polarized neutron diffraction experiments are reviewed. We discuss the qualitative features of the magnetic phase diagram in both zero magnetic field and in field and analyze the commensurate magnetic structure and its coupling to an applied electric field. The origin of ferroelectricity is discussed based on calculations of the ferroelectric polarization predicted by different microscopic coupling mechanisms (exchange-striction and cycloidal spin–orbit models). A minimal model containing a small set of parameters is also presented in order to understand the propagation of the magnetic structure along the c-direction.
TL;DR: In this paper, the long-range magnetic order co-exists with a shorter range order with a correlation length scale of ∼ 180 ˚A in the ab plane.
Abstract: . Below 25 K,the system orders magnetically with a modulated partially disorderedantiferromagnetic structure. We give a description of the magnetic interactions in the system whichis consistent with this magnetic structure. Our study also reveals that the long-range magneticorder co-exists with a shorter range order with a correlation length scale of ∼ 180 ˚A in the ab plane.Remarkably, on cooling, the volume of material exhibiting short range order increases at the expenseof the long-range order.
TL;DR: The element-specific magnetic structure of an epitaxially grown Mn_52Pd_48/Fe bilayer showing exchange bias was investigated with atomic-layer depth sensitivity at the antiferromagnet/ferromagnets interface by soft-x-ray magnetic circular dichroism and magnetic reflectivity.
Abstract: The element-specific magnetic structure of an epitaxially grown ${\mathrm{Mn}}_{52}{\mathrm{Pd}}_{48}/\mathrm{Fe}$ bilayer showing exchange bias was investigated with atomic-layer depth sensitivity at the antiferromagnet/ferromagnet interface by soft-x-ray magnetic circular dichroism and magnetic reflectivity. A complex magnetic interfacial configuration, consisting of a 2-monolayer-thick induced ferromagnetic region, and pinned uncompensated Mn moments that reach far deeper ($\ensuremath{\sim}13\text{ }\text{ }\AA{}$), both in the antiferromagnet, were found. For the latter, a direct relationship with the magnitude of the exchange bias is verified by similar measurements perpendicular to the field cooling direction.
TL;DR: In this article, the magnetic-field-induced martensitic transformation has been obtained in ferromagnetic shape memory alloys MnNiGa by doping a small amount of Co.
Abstract: With a high Curie temperature and low entropy change, the magnetic-field-induced martensitic transformation has been obtained in ferromagnetic shape memory alloys MnNiGa by doping a small amount of Co. Due to the ferromagnetic activation effect of Co, a large amount of antiferromagnetically aligned Mn moments are turned into ferromagnetic ordering, which is verified by our electronic structural calculation and experimental observation. Consequently, the magnetization rises up to 70emu∕g and the magnetization difference between two phases increases about ten times, resulting in a considerable dT∕dH of 4K∕T and a well-defined reversed transformation induced by a magnetic field.
TL;DR: In this paper, soft x-ray resonant magnetic diffraction at the Nd $M$ edges was performed on a Nd$M$ epitaxial film to investigate the magnetic ordering of the nd ions below the metal-insulator transition.
Abstract: Soft x-ray resonant magnetic diffraction at the Nd $M$ edges was performed on a $\mathrm{Nd}\mathrm{Ni}{\mathrm{O}}_{3}$ epitaxial film to investigate the magnetic ordering of the Nd ions below the metal-insulator transition. A noncollinear magnetic structure induced by the Ni magnetic moments best describes the azimuthal angle dependency of the $(1∕2,0,1∕2)$ reflection. This confirms the Ni spin structure observed with soft x-ray diffraction experiments performed at the Ni $L$ edge, providing further evidence of charge disproportionation without orbital order below the metal-insulator transition in $\mathrm{Nd}\mathrm{Ni}{\mathrm{O}}_{3}$.
TL;DR: In this paper, the relationship between the magnetic structure and ferroelectricity has been studied, where the magnetic order is closely related to the neutron magnetic scattering intensity, indicating that the magnetic orders are closely related with the magnetic strength.
Abstract: Neutron scattering studies and measurements of the dielectric susceptibility e and ferroelectric polarization P have been carried out under various magnetic fields H for single-crystal samples of the multiferroic system LiVCuO 4 with quasi one-dimensional spin 1/2 Cu 2+ chains formed of edge-sharing CuO 4 square planes, and the relationship between the magnetic structure and ferroelectricity has been studied. The ferroelectric polarization is significantly suppressed by the magnetic field H above 2 T applied along the a and b axes. When H = 0, a helical magnetic structure with the helical axis parallel to c has been confirmed. The magnetic structure under the field along a has been determined, where the a b -plane structure changes to the helical one with the helical axis parallel to H with increasing the field through ∼2 T. The ferroelectric polarization along a at H = 0 is found to be proportional to the neutron magnetic scattering intensity, indicating that the magnetic order is closely related to the ...
TL;DR: This study gives the first neutron magnetic structure evidence towards the microscopic understanding of the negative magnetization in the PBAs.
Abstract: A crossover of the field-cooled magnetization from positive to negative has been observed below the magnetic ordering temperature (17.9 K) in a multimetal Prussian Blue analogue (PBA), ${\mathrm{Cu}}_{0.73}{\mathrm{Mn}}_{0.77}[\mathrm{Fe}(\mathrm{CN}{)}_{6}]\ifmmode\cdot\else\textperiodcentered\fi{}z{\mathrm{H}}_{2}\mathrm{O}$. The reverse Monte Carlo (RMC) modeling (using the program RMCPOW) has been used to derive the various scattering contributions (e.g., nuclear diffuse, nuclear Bragg, magnetic diffuse, and magnetic Bragg) from the observed neutron diffraction patterns. The RMC analysis combined with the Rietveld refinement technique show an antiferromagnetic ordering of Mn moments with respect to the Cu as well as the Fe moments. Our study gives the first neutron magnetic structure evidence towards the microscopic understanding of the negative magnetization in the PBAs. This information can be effectively utilized to design suitable PBAs for making multifunctional devices.
TL;DR: Magnetic properties of the samples were strongly temperature and size dependent and a linear microwave frequency dependence of the resonance field and the increase in the blocking temperature of the particles by the particle size were also observed.
Abstract: In this study, size and surface effects on temperature and frequency dependent magnetic properties of superparamagnetic Fe3O4 nanoparticles in a size range of 1.1-11 nm are investigated by SPR technique. We used a theoretical formalism based on a distribution of diameters or volumes of the nanoparticles following lognormal proposed by Berger et al. The nanoparticles are considered as single magnetic domains with random orientations of magnetic moments and thermal fluctuations of anisotropic axes. The individual line shape function is derived from the damped precession equation of Landau-Lifshitz. Magnetic properties of the samples were strongly temperature and size dependent. The increase in SPR line width, the decrease in the resonance field and also increase in anisotropy filed by decreasing the temperature core-shell type structure of the nanoparticles and disordered magnetic structure (spin-glass like phase) of the particle surface. A linear microwave frequency dependence of the resonance field and the increase in the blocking temperature of the particles by the particle size were also observed.
TL;DR: In this article, the authors outline the region of metastability of C-type magnetic states, proving that they are indeed genuine and not a result of pinning on particle imperfections.
Abstract: Nanomagnetic systems of artificially shaped ferromagnetic islands recently became a popular subject due to their current and potential applications in spintronics [R. P. Cowburn, Nat. Mater. 6, 255 (2007)], magnetophotonics [A. Garcia-Martin, G. Armelles, and S. Pereira Phys. Rev. B 71, 205116 (2005)], and superconductivity. [D. S. Golubovic, W. V. Pogosov, M. Morelle, and V. V. Moshchalkov, Phys. Rev. Lett. 92, 177904 (2004)] When the island size is close to the exchange length of magnetic material (around 15nm), its magnetic structure becomes markedly different. It determines both static and dynamic magnetic properties of elements, but strongly depends on their shape and size. Here, we map this dependence for circular cylindrical islands of a few exchange lengths in size. We outline the region of metastability of C-type magnetic states, proving that they are indeed genuine and not a result of pinning on particle imperfections. A way to create the smallest particles with guaranteed magnetic vortex state ...
TL;DR: A new method, diffraction spectroscopy, based on the photon energy dependence of the angular distribution of Auger electron emission, is applied to analyze the magnetic structure of a Ni ultrathin film on a Cu(001) surface around the spin reorientation transition.
Abstract: Up until now there has been no direct method for detecting the electronic and magnetic structure of each atomic layer at the surface, which is an essential analysis technique for nanotechnology. For this purpose, we have developed a new method, diffraction spectroscopy, based on the photon energy dependence of the angular distribution of Auger electron emission. We have applied this method to analyze the magnetic structure of a Ni ultrathin film on a Cu(001) surface around the spin reorientation transition. Atomic-layer resolved x-ray absorption and magnetic circular dichroism spectra were obtained. Surface and interior core-level shifts and magnetic moments are determined for each atomic layer individually.
TL;DR: Van der Laan et al. as discussed by the authors used soft X-ray resonant magnetic scattering to investigate magnetic superlattices and magnetic domain structures on the nanoscopic length scale.
TL;DR: The magnetic properties of RMn2O5 multiferrroics as obtained by unpolarized and polarized neutron diffraction experiments are reviewed in this paper, where qualitative features of the magnetic phase diagram both in zero magnetic field and in field and analyze the commensurate magnetic structure and its coupling to an applied electric field.
Abstract: The magnetic properties of RMn2O5 multiferrroics as obtained by unpolarized and polarized neutron diffraction experiments are reviewed. We discuss the qualitative features of the magnetic phase diagram both in zero magnetic field and in field and analyze the commensurate magnetic structure and its coupling to an applied electric field. The origin of ferrolectricity is discussed based on calculations of the ferroelectric polarization predicted by different microscopic coupling mechanisms (exchange striction and cycloidal spin-orbit models). A minimal model containing a small set of parameters is also presented in order to understand the propagation of the magnetic structure along the c-direction.
TL;DR: In this paper, the magnetoelectric phase control in a magnetic system showing cycloidal/conical spiral spin order is reviewed, where the magneto-electric properties can be readily controlled by the use of magnetic fields.
Abstract: Since the discovery of ferroelectric activity as well as colossal magnetoelectric response in a perovskite-type manganite TbMnO3, the study of a new class of magnetoelectric multiferroics has been attracting a great deal of interest In these multiferroics, ferroelectric order develops upon a magnetic phase transition into some spiral magnetic ordered phases such as a cycloidal or transverse conical structure Since the origin of ferroelectricity is attributed to magnetism in these multiferroics, ferroelectric properties can be readily controlled by the use of magnetic fields We review the magnetoelectric phase control in a magnetic system showing cycloidal/conical spiral spin order
TL;DR: It is shown that the magnetic structure changes dramatically across the entire nanowire if one single atom is added to it, and this extremely nonlocal effect occurs only for nanosized wires.
Abstract: The parity of the number of atoms in finite antiferromagnetic nanowires deposited on ferromagnets is shown to be a crucial quantity determining their magnetic ground state. Relating results of the full-potential Korringa-Kohn-Rostoker method for noncollinear magnetism from first principles to a Heisenberg model, we show that the magnetic structure changes dramatically across the entire nanowire if one single atom is added to it. Infinite and finite even-numbered nanochains exhibit always noncollinear magnetism, while odd-numbered wires lead under given conditions to a collinear ferrimagnetic ground state. This extremely nonlocal effect occurs only for nanosized wires.
TL;DR: Neutron diffraction, susceptibility and magnetization measurements were performed on iron borates RFe(3)(BO(3))(4) (R = Pr, Er) to investigate details of the crystallographic structure, the low temperature magnetic structures and transitions and to study the role of the rare earth anisotropy.
Abstract: Neutron diffraction, susceptibility and magnetization measurements (for R = Er only) were performed on iron borates RFe(3)(BO(3))(4) (R = Pr, Er) to investigate details of the crystallographic structure, the low temperature magnetic structures and transitions and to study the role of the rare earth anisotropy. PrFe(3)(BO(3))(4), which crystallizes in the spacegroup R32, becomes antiferromagnetic at T(N) = 32 K, with τ = [0 0 3/2], while ErFe(3)(BO(3))(4), which keeps the P3(1)21 symmetry over the whole studied temperature range 1.5 K < T < 520 K, becomes antiferromagnetic below T(N) = 40 K, with τ = [0 0 1/2]. Both magnetic propagation vectors lead to a doubling of the crystallographic unit cell in the c-direction. Due to the strong polarization of the Fe-sublattice, the magnetic ordering of the rare earth sublattices appears simultaneously at T(N). The moment directions are determined by the rare earth anisotropy: easy-axis along c for PrFe(3)(BO(3))(4) and easy-plane a-b for ErFe(3)(BO(3))(4). There are no spin reorientations present in either of the two compounds but there is the appearance below 10 K of a minority phase in the Er-compound adopting a 120° arrangement of the Er-moments.
TL;DR: In this paper, the structural and magnetic properties of polycrystalline Cu 1− x TM x O samples were investigated by means of temperature dependent magnetic susceptibility and room temperature X-ray powder diffraction (XRPD).
Abstract: Polycrystalline Cu 1− x TM x O samples ( x = 0 and 0.06; TM = Ni 2+ and Fe 3+ ) were grown using a co-precipitation method. The structural and magnetic properties were investigated by means of temperature dependent magnetic susceptibility and room temperature X-ray powder diffraction (XRPD). The XRPD analyses of the samples reveal the formation of single phase with structure isomorphous to the CuO. Interestingly, T -dependent magnetization shows the reduction of Neel temperature, T N , from 213 K in the copper oxide to 70 K in the Fe-doped sample ( x = 0.06). Because in the Ni-doped samples T N seems to be unaffected, this decrease in T N is believed to be due to the different electronic structure of the dopant. The ferromagnetic behavior observed at room temperature in all samples can be related to both the level of oxygen (excess or vacancy) of our samples and to the difference in the magnetic structure of the dopant.
TL;DR: In this article, the antiferromagnetic transition in the rare earth (R) tritelluride RTe{sub 3} family of charge density wave (CDW) compounds via specific heat, magnetization and resistivity measurements was investigated.
Abstract: The antiferromagnetic transition is investigated in the rare-earth (R) tritelluride RTe{sub 3} family of charge density wave (CDW) compounds via specific heat, magnetization and resistivity measurements. Observation of the opening of a superzone gap in the resistivity of DyTe{sub 3} indicates that additional nesting of the reconstructed Fermi surface in the CDW state plays an important role in determining the magnetic structure.
TL;DR: The magnetic field dependence of the ferroelectric polarization and the spin-lattice coupling in multiferroic multi-materials has been investigated in this article, where the magnetic field is applied along the easy axis and spin easy axis.
Abstract: The magnetic-field dependence of the ferroelectric polarization and the spin-lattice coupling in multiferroic $\mathrm{Mn}\mathrm{W}{\mathrm{O}}_{4}$ have been investigated The ferroelectric transition from the low temperature paraelectric phase occurs when the magnetic field is applied along the $a$, $c$, and the spin easy axes The ferroelectric polarization in the magnetic field along the $a$ and the $c$ axis shows a contrasting behavior depending on the field direction, possibly reflecting the relative configuration between the crystallographic axis and the magnetic principal axis in the $ac$ plane Incommensurate lattice modulation observed in the ferroelectric spiral-spin phase confirms the existence of spin-lattice coupling in $\mathrm{Mn}\mathrm{W}{\mathrm{O}}_{4}$ The lattice modulation indicates that the ferroelectric AF2 phase also takes the incommensurate magnetic structure in a magnetic field In the high-field phase, which appears in high magnetic fields above $12\phantom{\rule{03em}{0ex}}\mathrm{T}$ along the easy axis, the magnetic-field-induced ferroelectric polarization disappeared
TL;DR: The crystal and magnetic structures of SrFe 2+2 (PO 4 ) 2 have been determined by neutron powder diffraction data at low temperatures (space group P 2 1 / c (no. 14); Z =4; a =9.35417(13) A, b =6.83808(10)A, c =10.51899(15)A), and β =109.5147(7)° at 15 K) as discussed by the authors.