Showing papers on "Metamagnetism published in 2018"
TL;DR: High calculated selectivity of CO2 over N2 and CH4 reveals the potential application of MFUM-1(Cu) in practical systems of gas separation and the application of carbon dioxide from nitrogen and also from methane was theoretically investigated.
Abstract: A magnetic metal organic framework {[Cu(but-1,4-dc)05(N3)(H2O)]·H2O}n (MFUM-1(Cu)) (but-1,4-dc = butane-1,4-dicarboxylate) was synthesized and characterized structurally and magnetically In MFUM-1(Cu), each CuII ion has a distorted octahedral geometry with an obvious Jahn–Teller distortion, where the coordination environment is composed of mixed EO-azido/aliphatic based carboxylate/H2O threefold bridges These bridges extend the structure of MFUM-1(Cu) in two dimensions by covalent connectivity and form square-shaped channels Also, a study was done to determine the effectiveness of sonochemical synthesis for the preparation of nano-sheets of MFUM-1(Cu) and subsequently the influence of particle size on physical properties such as magnetic behavior and thermal stability The particles were characterized by elemental analyses, infrared spectroscopy (IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and powder X-ray diffraction (PXRD) analyses The effects of parameters such as concentration, solvent, and reaction time on the size distribution, morphology, and yield of product were carefully studied The magnetic properties of MFUM-1(Cu) and corresponding nano-structure were examined which indicated metamagnetism with strong intrachain ferromagnetic coupling versus the weak interchain antiferromagnetic coupling Finally, the application of MFUM-1(Cu) in the separation of carbon dioxide from nitrogen and also from methane was theoretically investigated High calculated selectivity of CO2 over N2 and CH4 reveals the potential application of MFUM-1(Cu) in practical systems of gas separation
33 citations
TL;DR: In this paper, a polycrystalline sample of a double perovskite crystal structure of a ferrimagnetic oxide with three different magnetic ions was used to investigate its magnetization reversal and inverse hysteresis loop.
Abstract: ${\mathrm{Er}}_{2}{\mathrm{CoMnO}}_{6}$ is a ferrimagnetic oxide consisting of both $4f$ and $3d$ magnetic ions in a monoclinic double perovskite crystal structure (space group $P{2}_{1}/n$) The present work probes some novel magnetic features associated with its ferrimagnetic state on a polycrystalline sample of ${\mathrm{Er}}_{2}{\mathrm{CoMnO}}_{6}$ A clear low temperature compensation point followed by negative magnetization is observed in the field-cooled state of the sample The sample shows a large field-induced change in entropy at very low temperature, which is related to the observed metamagnetism Interestingly, ${\mathrm{Er}}_{2}{\mathrm{CoMnO}}_{6}$ is found to show remarkable feature of inverse hysteresis loop which is quite rare among bulk ferrimagnets Presence of three different magnetic ions, with $4f$ moment of Er having larger uniaxial anisotropy, is likely to be responsible for the observed magnetization reversal and inverse hysteresis loop The sample also shows inverse exchange bias effect, which is presumably related to the negative exchange interaction at the interface of ordered and antisite disordered ferrimagnetic phases Such antisite disorder is quite common among the metal oxides having double perovskite structure
33 citations
TL;DR: In this paper, the authors report neutron diffraction, transport, and magnetization measurements of thin films of doped EuTiO3, an itinerant magnetic material, as a function of carrier density and magnetic field.
Abstract: In materials with broken time-reversal symmetry, the Berry curvature acts as a reciprocal space magnetic field on the conduction electrons and is a significant contribution to the magnetotransport properties, including the intrinsic anomalous Hall effect. Here, we report neutron diffraction, transport, and magnetization measurements of thin films of doped EuTiO3, an itinerant magnetic material, as a function of carrier density and magnetic field. These films are itinerant antiferromagnets at all doping concentrations. At low carrier densities, the magnetoresistance indicates a metamagnetic transition, which is absent at high carrier densities (>6 × 1020 cm−3). Strikingly, the crossover coincides with a sign change in the spontaneous Hall effects, indicating a sign change in the Berry curvature. We discuss the results in the context of the band structure topology and its coupling to the magnetic texture.
29 citations
TL;DR: The static and dynamic magnetic data revealed that spin-canting in the 1D-chain of 1 results in the single-chain magnet (SCM) behavior with high spin-reversal energy barrier Ueff (Δτ) = 87.5 K, exhibiting magnetic hysteresis below 4 K and coexistence with the metamagnetism altogether resulting in weak 3D-ferromagnetic behavior.
Abstract: Peculiar magnetic behavior was found for 1D-polymeric seven-coordinate pentagonal bipyramidal Fe(II) complex {[Fe(L)(μ1,3-N3)](ClO4)} n (1) with a pentadentate macrocyclic ligand L (3,12,18-triaza-6,9-dioxabicyclo[12.3.1]octadeca-1(18),14,16-triene) coordinated in the pentagonal equatorial plane and with end-to-end bridging azido ligands in axial positions. The static and dynamic magnetic data revealed that spin-canting in the 1D-chain of 1 results in the single-chain magnet (SCM) behavior with high spin-reversal energy barrier Ueff (Δτ) = 87.5 K, exhibiting magnetic hysteresis below 4 K and coexistence with the metamagnetism altogether resulting in weak 3D-ferromagnetic behavior. This is the first reported example of the exclusively azido-bridged homospin Fe(II)-based SCM.
27 citations
TL;DR: In this paper, the effect of H, B, C, and N interstitials on the electronic, lattice and magnetic properties of La(Fe,Si)$13}$ using density functional theory was investigated.
Abstract: We present a systematic investigation of the effect of H, B, C, and N interstitials on the electronic, lattice and magnetic properties of La(Fe,Si)$_{13}$ using density functional theory. The parent LaSiFe$_{12}$ alloy has a shallow, double-well free energy function that is the basis of itinerant metamagnetism. On increasing the dopant concentration, the resulting lattice expansion causes an initial increase in magnetisation for all interstitials that is only maintained at higher levels of doping in the case of hydrogen. Strong s-p band hybridisation occurs at high B,C and N concentrations. We thus find that the electronic effects of hydrogen doping are much less pronounced than those of other interstitials, and result in the double-well structure of the free energy function being least sensitive to the amount of hydrogen. This microscopic picture accounts for the vanishing first order nature of the transition by B,C, and N dopants as observed experimentally. We use our calculated electronic density of states for LaSiFe$_{12}$ and the hydrogenated alloy to infer changes in magneto-elastic coupling and in phonon entropy on heating through $T_C$ by calculating the fermionic entropy due to the itinerant electrons. Lastly, we predict the electron thermopower in a spin-mixing, high temperature limit and compare our findings to recent literature data.
18 citations
TL;DR: In this article, the authors show that a metamagnetic texture can be created by the chiral twisting effects of the asymmetric Dzyaloshinskii-Moriya (DM) exchange.
Abstract: The notion of a simple ordered state implies homogeneity. If the order is established by a broken symmetry, elementary Landau theory of phase transitions shows that only one symmetry mode describes this state. Precisely at points of phase coexistence domain states formed of large regions of different phases can be stabilized by long range interactions. In uniaxial antiferromagnets the so-called metamagnetism is an example of such a behavior, when an antiferromagnetic and field-induced spin-polarized paramagnetic/ferromagnetic state co-exist at a jump-like transition in the magnetic phase diagram. Here, combining experiment with theoretical analysis, we show that a different type of mixed state between antiferromagnetism and ferromagnetism can be created in certain acentric materials. In the small-angle neutron scattering experiments we observe a field-driven spin-state in the layered antiferromagnet Ca3Ru2O7, which is modulated on a scale between 8 and 20 nm and has both antiferromagnetic and ferromagnetic parts. We call this state a metamagnetic texture and explain its appearance by the chiral twisting effects of the asymmetric Dzyaloshinskii-Moriya (DM) exchange. The observation can be understood as an extraordinary coexistence, in one thermodynamic state, of spin orders belonging to different symmetries. Experimentally, the complex nature of this metamagnetic state is demonstrated by measurements of anomalies in electronic transport which reflect the spin-polarization in the metamagnetic texture, determination of the magnetic orbital moments, which supports the existence of strong spin-orbit effects, a pre-requisite for the mechanism of twisted magnetic states in this material.
16 citations
TL;DR: The results imply rich physics in the random mixed-metal systems and demonstrate the possibility of improving single-chain relaxation properties by blending metal ions.
Abstract: A series of isomorphous compounds of general formula [Co1–xNix(tzpo)(N3)(H2O)2]n·nH2O (x = 0, 0.19, 0.38, 0.53, 0.68, 0.84, and 1; tzpo = 4-(5-tetrazolate)pyridine-N-oxide) was prepared. The compounds consist of homometallic or heterometallic chains with simultaneous azide-tetrazolate bridges. The heterometallic systems feature random distribution of metal ions. All compounds across the series exhibit intrachain ferromagnetic coupling, interchain antiferromagnetic (AF) ordering, field-induced metamagnetic transition, and, except the Ni-only compound, single-chain magnetic dynamics. The AF ordering temperature, the metamagnetic critical field, and the relaxation parameters show different composition dependence. Notably, the blocking temperature for the Co-rich materials is higher than the Co-only compound, suggesting synergy between the randomly distributed Co(II) and Ni(II) ions in promoting slow relaxation. The results imply rich physics in the random mixed-metal systems and demonstrate the possibility o...
15 citations
TL;DR: In this paper, textured and dense Mn0.97Fe0.03CoSi and Mn 0.88CoSi compounds are prepared through a high-magnetic-field solidification approach and large room-temperature and reversible magnetostriction effects are observed in these compounds at low magnetic field.
Abstract: The MnCoSi compound is a potential magnetostriction material since the magnetic field can drive a metamagnetic transition from an antiferromagnetic phase to a high magnetization phase in it, which accompanies a large lattice distortion. However, a large driving magnetic field, magnetic hysteresis, and poor mechanical properties seriously hinder its application for magnetostriction. By substituting Fe for Mn and introducing vacancies of the Mn element, textured and dense Mn0.97Fe0.03CoSi and Mn0.88CoSi compounds are prepared through a high-magnetic-field solidification approach. As a result, large room-temperature and reversible magnetostriction effects are observed in these compounds at a low magnetic field. The origin of this large magnetostriction effect and potential applications are discussed.
15 citations
TL;DR: In this article, a combination of quantum Monte Carlo and exact methods is used to study the field-driven saturation transition of the two-dimensional $J\text{\ensuremath{-}}Q$ model, in which the antiferromagnetic Heisenberg exchange $(J)$ coupling competes with an additional four-spin interaction $(Q)$ that favors valence-bond solid order.
Abstract: Using a combination of quantum Monte Carlo and exact methods, we study the field-driven saturation transition of the two-dimensional $J\text{\ensuremath{-}}Q$ model, in which the antiferromagnetic Heisenberg exchange $(J)$ coupling competes with an additional four-spin interaction $(Q)$ that favors valence-bond solid order. For small values of $Q$, the saturation transition is continuous and is expected to be governed by zero-scale-factor universality at its upper critical dimension, with a specific form of logarithmic corrections to scaling (first proposed by Sachdev et al. [Phys. Rev. B 50, 258 (1994)]). Our results conform to this expectation, but the logarithmic corrections to scaling do not match the form predicted by Sachdev et al. We also show that the saturation transition becomes first order above a critical coupling ratio ${(Q/J)}_{\mathrm{min}}$ and is accompanied by magnetization jumps---metamagnetism. We obtain an exact solution for ${(Q/J)}_{\mathrm{min}}$ using a high magnetization expansion, and confirm the existence of the magnetization jumps beyond this value of coupling using quantum Monte Carlo simulations.
13 citations
TL;DR: The magnetic properties of a series of isomorphous metal-organic frameworks based on random heterometallic Co1-xNix chains with simultaneous azide, carboxylate and tetrazolate bridges are reported, suggesting that the randomly distributed metal ions have synergistic effects on slow relaxation of magnetization.
Abstract: This paper reports the magnetic properties of a series of isomorphous metal–organic frameworks based on random heterometallic Co1−xNix chains with simultaneous azide, carboxylate and tetrazolate bridges. All the mixed-metal compounds show intrachain FM interactions, field-induced metamagnetism, and SCM-like slow magnetic relaxation. These behaviors are quite different from the parent Co(II) and Ni(II) materials, and even a small amount of metal replacement can cause significant magnetic changes. The static properties such as AF ordering, metamagnetic critical field and the hysteresis parameters show complicated composition dependence. Most interestingly, the mixed-metal systems can show a higher blocking temperature than the Co(II) compound, suggesting that the randomly distributed metal ions have synergistic effects on slow relaxation of magnetization. This is phenomenologically associated with the competitive effects of Δτ and τo.
13 citations
TL;DR: In this paper, the results of detailed investigations of magnetization, heat-capacity, dielectric, pyrocurrent, and magneto(di)electric measurements on Tb2BaCoO5, belonging to a hitherto unexplored spin-chain cobaltate family, R2BaCOO5 (R = Rare-earths).
Abstract: We report the results of detailed investigations of magnetization, heat-capacity, dielectric, pyrocurrent, and magneto(di)electric measurements on Tb2BaCoO5, belonging to a hitherto unexplored spin-chain cobaltate family, R2BaCoO5 (R = Rare-earths). The magnetic measurements reveal that this compound exhibits an antiferromagnetic transition at (TN=) 18.8 K and there is a spin reorientation beyond 40 kOe below TN. Dielectric and pyrocurrent data measured as a function of temperature and magnetic field establish that this compound is a “type-II” multiferroic material. The most fascinating finding which we would like to emphasize is that the observed value of the magneto-dielectric effect beyond the metamagnetic transition field is the largest (close to 55%, below 10 K, for H = ∼100 kOe) ever reported for polycrystals of a compound in the bulk form, thereby offering a hope to find a single-phase polycrystalline compound at room temperature to enable ease of applications.
TL;DR: In this article, it was shown that epitaxial film strain significantly modifies the properties of strontium ruthenates and exhibits a range of unusual emergent properties, such as electron nematic behavior and metamagnetism.
Abstract: $\mathrm{S}{\mathrm{r}}_{3}\mathrm{R}{\mathrm{u}}_{2}{\mathrm{O}}_{7}$ belongs to the family of layered strontium ruthenates and exhibits a range of unusual emergent properties, such as electron nematic behavior and metamagnetism. Here, we show that epitaxial film strain significantly modifies these phenomena. In particular, we observe enhanced magnetic interactions and an electron nematic phase that extends to much higher temperatures and over a larger magnetic-field range than in bulk single crystals. Furthermore, the films show an unusual anisotropic non-Fermi-liquid behavior that is controlled by the direction of the applied magnetic field. At high magnetic fields, the metamagnetic transition to a ferromagnetic phase recovers isotropic Fermi-liquid behavior. The results support the interpretation that these phenomena are linked to the special features of the Fermi surface, which can be tuned by both film strain and an applied magnetic field.
TL;DR: In this paper, the authors used neutron diffraction to study magnetic order in rare-earth pyrogermanates and found the lowest Neel temperature in the pyrochlore family of 1.15 K.
Abstract: The recent discoveries of proximate quantum spin-liquid compounds and their potential application in quantum computing informs the search for new candidate materials for quantum spin-ice and spin-liquid physics. While the majority of such work has centered on members of the pyrochlore family due to their inherently frustrated linked tetrahedral structure, the rare-earth pyrogermanates also show promise for possible frustrated magnetic behavior. With the familiar stoichiometry $RE_2$Ge$_2$O$_7$, these compounds generally have tetragonal symmetry with a rare-earth sublattice built of a spiral of alternating edge and corner sharing rare-earth site triangles. Studies on Dy$_2$Ge$_2$O$_7$ and Ho$_2$Ge$_2$O$_7$ have shown tunable low temperature antiferromagnetic order, a high frustration index and spin-ice like dynamics. Here we use neutron diffraction to study magnetic order in Er$_2$Ge$_2$O$_7$ (space group $P4_{1}2_{1}2$ ) and find the lowest yet Neel temperature in the pyrogermanates of 1.15 K. Using neutron powder diffraction we find the magnetic structure to order with $k = (0,0,0)$ ordering vector, magnetic space group symmetry $P4_{1}^{'}2_{1}2^{'}$ and a refined Er moment of $m = 8.1 \mu_B$ - near the expected value for the Er$^{3+}$ free ion. Provocatively, the magnetic structure exhibits similar 'local-Ising' behavior to that seen in the pyrocholres where the Er moment points up or down along the short Er-Er bond. Upon applying a magnetic field we find a first order metamagnetic transition at $\sim$ 0.35 T to a lower symmetry $P2_{1}^{'}2_{1}^{'}2$ structure. This magnetic transition involves an inversion of Er moments aligned antiparallel to the applied field describing a class I spin-flip type transition, indicating a strong local anisotropy at the Er site - reminiscent of that seen in the spin-ice pyrochlores.
TL;DR: In this article, pressure-induced intralayer itinerant magnetism arising from the interlayer ferromagnetism was revealed, where the application of modest hydrostatic pressure generates anisotropy that may cause flattening and tilting of RuO${}_{6}$ octahedra.
Abstract: Triple-layered Sr${}_{4}$Ru${}_{3}$O${}_{10}$ presents a rare case of coexistence of interlayer ($c$-axis) ferromagnetism and intralayer (basal-plane) metamagnetism at ambient pressure. This study reveals the pressure-induced intralayer itinerant antiferromagnetism arising from the interlayer ferromagnetism. The application of modest hydrostatic pressure generates anisotropy that may cause flattening and tilting of RuO${}_{6}$ octahedra. These lattice distortions weaken the $c$-axis ferromagnetism as well as the basal-plane metamagnetism, while inducing a basal-plane, itinerant antiferromagnetic state that is remarkably uncommon. The unusually large magnetoelastic coupling inherent in this ruthenate makes it an ideal model system for studies of itinerant magnetism.
TL;DR: The structural, magnetic, and ferroelectric properties of BaTiO3 modified BiCoO3i are studied and the partial polarization analysis shows that not only the lone pair at Bi sites but also the d0-ness of Ti4+ ions contribute to the net polarization.
Abstract: In order to establish the correlation between the magnetoelectric coupling and magnetic instability, we have studied the structural, magnetic, and ferroelectric properties of BaTiO3 modified BiCoO3ie xBaTiO3–(1 − x)BiCoO3 as a function of BaTiO3 concentration (x) and volume from a series of general-gradient-corrected (GGA), GGA plus onsite Coulomb repulsion (U), full potential, spin-density-functional band-structure calculations within the framework of density functional theory along with synchrotron X-ray diffraction and magnetic measurement studies G-type antiferromagnetic ordering was found to be energetically favorable among all the considered magnetic configurations for x < 045 and higher concentrations stabilize with nonmagnetic (NM) states We observe metamagnetic spin state transitions associated with paraelectric to ferroelectric transitions as a function of volume and x using synchrotron diffraction and computational studies, indicating a strong magnetoelectric coupling Specifically for x = 033 composition, a pressure induced high spin (HS) to low spin (LS) transition occurs when the volume is compressed below 25% Our orbital-projected density of states show a HS state for Co3+ in the ferroelectric ground state for x < 045 and the corresponding paraelectric phase is stable in the NM state due to the stabilization of LS state as evident from our fixed-spin-moment calculations and magnetic measurements The nature of chemical bonding has been studied using partial density of states, electron localization function, and Born effective charge analysis High values of spontaneous ferroelectric polarizations are predicted for lower x values which inversely vary with x because of the reduction of tetragonality (c/a) with increase in x which indicates the presence of both spin–lattice and ferroelectricity–lattice coupling Our partial polarization analysis shows that not only the lone pair at Bi sites but also the d0-ness of Ti4+ ions contribute to the net polarization Moreover, we find that the HS–LS transition point and magnetoelectric coupling strength can be varied by x
TL;DR: At room-temperature two-dimensional nanosheets of a MOF comprised of cobalt(II) ion with benzenedicarboxylic acid ligand, which exhibited unusual magnetic properties was synthesized, substantiated by the alternating-current magnetic susceptibility measurements.
Abstract: Herein, we have synthesized at room-temperature two-dimensional nanosheets of a MOF comprised of cobalt(II) ion with benzenedicarboxylic acid ligand, which exhibited unusual magnetic properties. D...
TL;DR: In this paper, the synthesis, structural characterization, and magnetic properties of Pr0.65Ca0.3M0.05MnO3 (M = Na, K and Ag) perovskite manganites are reported.
Abstract: The synthesis, structural characterization, and magnetic properties of Pr0.65Ca0.3M0.05MnO3 (M = Na, K and Ag) perovskite manganites are reported. Our samples were synthesized using the solid state reaction method at high temperature. Rietveld refinements of the X-ray diffraction patterns show that all our samples are single phase and crystallize in the distorted orthorhombic system with Pbnm space group. The surface morphology and infrared absorption of the samples were systematically investigated. Magnetization measurements versus temperature in a magnetic applied field of 50 mT showed that the antiferromagnetic ordering temperature TAFM occurring below the charge-ordering transition temperature TCO in these narrow band manganites are slightly dependent with monovalent element. The critical magnetic field (Hc) required for metamagnetism is found to reduce drastically from 7 T for Pr0.65Ca0.35MnO3 to 2.9 T for Pr0.65Ca0.3Na0.05MnO3.
TL;DR: In this article, orthorhombic CeNiSiSi2-type polycrystalline RNiSi2 (R=Gd, Dy, Ho, Er, Tm) compounds were synthesized and the magnetic and magnetocaloric properties were investigated in detail.
Abstract: Orthorhombic CeNiSi2-type polycrystalline RNiSi2 (R=Gd, Dy, Ho, Er, Tm) compounds were synthesized and the magnetic and magnetocaloric properties were investigated in detail. The transition temperatures of RNiSi2 compounds are all in a very low temperature range (<30 K). As temperature increases, all of the compounds undergo an AFM to PM transition (GdNiSi2 at 18 K, DyNiSi2 at 25 K, HoNiSi2 at 10.5 K, ErNiSi2 at 3 K and TmNiSi2 at 3.5 K, respectively). ErNiSi2 compound shows the largest (ΔSM)max (maximal magnetic entropy change) among these compounds. The value of (ΔSM)max is 27.9 J/kgK under a field change of 0-5 T, which indicates that ErNiSi2 compound is very competitive for practical applications in low-temperature magnetic refrigeration in the future. DyNiSi2 compound shows large inverse MCE (almost equals to the normal MCE) below the TN which results from metamagenitic transition under magnetic field. Considering of the normal and inverse MCE, DyNiSi2 compound also has potential applications in low-...
TL;DR: In this paper, complex metamagnetic transitions in single crystals of the new low carrier Kondo antiferromagnet YbRh3Si7 are reported, and the origin of the anomalous metamagnetism is related to competition between crystal electric field anisotropy and anisotropic exchange interactions.
Abstract: We report complex metamagnetic transitions in single crystals of the new low carrier Kondo antiferromagnet YbRh3Si7. Electrical transport, magnetization, and specific heat measurements reveal antiferromagnetic order at T_N = 7.5 K. Neutron diffraction measurements show that the magnetic ground state of YbRh3Si7 is a collinear antiferromagnet where the moments are aligned in the ab plane. With such an ordered state, no metamagnetic transitions are expected when a magnetic field is applied along the c axis. It is therefore surprising that high field magnetization, torque, and resistivity measurements with H||c reveal two metamagnetic transitions at mu_0H_1 = 6.7 T and mu_0H_2 = 21 T. When the field is tilted away from the c axis, towards the ab plane, both metamagnetic transitions are shifted to higher fields. The first metamagnetic transition leads to an abrupt increase in the electrical resistivity, while the second transition is accompanied by a dramatic reduction in the electrical resistivity. Thus, the magnetic and electronic degrees of freedom in YbRh3Si7 are strongly coupled. We discuss the origin of the anomalous metamagnetism and conclude that it is related to competition between crystal electric field anisotropy and anisotropic exchange interactions.
TL;DR: In this article, the authors have synthesized the new YbMn6−yFeySn6 alloys and investigated their crystal and magnetic properties using X-ray diffraction and magnetization measurements.
TL;DR: In this paper, the magnetocaloric properties of the intermetallic DyCo2 compound and its correlations with the itinerant electron metamagnetism (IEM) phenomenon and structural disorders are investigated and discussed.
TL;DR: In this paper, the synthesis, crystal structure and magnetic studies for a two-dimensional network of mixed-valent {Mn6} cages were reported, which contained three different bridging ligands: pivalate, phenylphosphonate and partially deprotonated triethanolamine.
Abstract: The synthesis, crystal structure and magnetic studies are reported for a two-dimensional network of mixed-valent {Mn6} cages. The compound contains three different bridging ligands: pivalate, phenylphosphonate and partially deprotonated triethanolamine. The result of using three bridging ligands is a complex structure involving a {MnIII2MnII4} edge-sharing bitetrahedron that interlinks, forming a layered structure. Weak intercage interactions lead to a remarkably complicated magnetic behaviour, with a phase transition at 2.1 K leading to a canted antiferromagnetic state.
TL;DR: A broad set of charge transfer excitations in the spin down channel which are sensitive to the metamagnetic transition involving the spin state on Co centers are revealed and photoconductivity that depends on an applied magnetic field is shown.
Abstract: We combine magnetic circular dichroism and photoconductivity with prior optical absorption and first principles calculations to unravel spin-charge interactions in the high Curie temperature magnet CoFe2O4. In addition to revising the bandgap hierarchy, we reveal a broad set of charge transfer excitations in the spin down channel which are sensitive to the metamagnetic transition involving the spin state on Co centers. We also show photoconductivity that depends on an applied magnetic field. These findings open the door for the creation and control of spin-polarized electronic excitations from the minority channel charge transfer in spinel ferrites and other earth-abundant materials.
TL;DR: In this article, the authors present magnetization measurements on Sr 4 Ru 3 O 10 as a function of temperature and magnetic field applied perpendicular to the magnetic easy c-axis inside the ferromagnetic phase, and conclude that the double metamagnetic transition is an intrinsic effect of the material and it is not caused by sample stacking faults such as twinning or partial inplane rotation between layers.
Abstract: We present magnetization measurements on Sr 4 Ru 3 O 10 as a function of temperature and magnetic field applied perpendicular to the magnetic easy c-axis inside the ferromagnetic phase. Peculiar metamagnetism evolves in Sr 4 Ru 3 O 10 below the ferromagnetic transition T C as a double step in the magnetization at two critical fields H c 1 and H c 2 . We map the H − T phase diagram with special focus on the temperature range 50 K ≤ T ≤ T C . We find that the critical field H c 1 ( T ) connects the field and temperature axes of the phase diagram, whereas the H c 2 boundary starts at 2.8 T for the lowest temperatures and ends in a critical endpoint at (1 T; 80 K). We conclude from the temperature dependence of the ratio Hc 1 Hc 2 ( T ) that the double metamagnetic transition is an intrinsic effect of the material and it is not caused by sample stacking faults such as twinning or partial in-plane rotation between layers.
TL;DR: In this article, the Frank-Kasper cage compound EuV 2 Al 20 crystallizes in the cubic structure with Fd 3 ‾ m space group and exhibits unusual magnetic and transport properties.
TL;DR: In this paper, the magnetic properties of EuMn0.5Co0.3 perovskite were studied under various conditions in fields up to 140 kOe.
Abstract: The magnetic properties of the EuMn0.5Co0.5O3 perovskite synthesized under various conditions are studied in fields up to 140 kOe. The sample synthesized at T = 1500°C is shown to exhibit a metamagnetic phase transition, which is irreversible below T = 40 K, and the sample synthesized at T = 1200°C demonstrates the field dependence of magnetization that is typical of a ferromagnet. Both samples have TC = 123 K and approximately the same magnetization in high magnetic fields. The metamagnetism is assumed to be related to a transition from a noncollinear ferromagnetic phase to a collinear phase, and the presence of clusters with ordered Co2+ and Mn4+ ions leads to ferromagnetism. The noncollinear phase is formed due to the competition between positive Co2+–Mn4+ and negative Mn4+–Mn4+ and Co2+–Co2+ interactions, which make almost the same contributions, and to the existence of a high magnetic anisotropy.
01 Jan 2018
TL;DR: The field of strongly correlated electrons is dominated by emergent phenomena exhibiting exotic and intriguing properties, and identifying and characterising these phases has been the challenge for condensed matter physicists for the last few decades as mentioned in this paper.
Abstract: As outlined in Chap. 1, the field of strongly correlated electrons is dominated by emergent phenomena exhibiting exotic and intriguing properties. Identifying and characterising these phases has been the challenge for condensed matter physicists for the last few decades.
TL;DR: A series of random bimetallic NiII-MnII compounds with N-methylpyridinium-4-carboxylate (4-mpc) and azide, have been synthesized and characterized as discussed by the authors.