Metamagnetic Properties Research Articles

Spin-Lattice Coupled Metamagnetism in Frustrated van der Waals Magnet CrOCl.

The long-range magnetic ordering in frustrated magnetic systems is stabilized by coupling magnetic moments to various degrees of freedom, for example, by enhancing magnetic anisotropy via lattice distortion. Here, the unconventional spin-lattice coupled metamagnetic properties of atomically-thin CrOCl, a van der Waals antiferromagnet with inherent magnetic frustration rooted in the staggered square lattice, are reported. Using temperature- and angle-dependent tunneling magnetoconductance (TMC), in complementary with magnetic torque and first-principles calculations, the antiferromagnetic (AFM)-to-ferrimagnetic (FiM) metamagnetic transitions (MTs) of few-layer CrOCl are revealed to be triggered by collective magnetic moment flipping rather than the established spin-flop mechanism, when external magnetic field (H) enforces a lattice reconstruction interlocked with the five-fold periodicity of the FiM phase. The spin-lattice coupled MTs are manifested by drastic jumps in TMC, which show anomalous upshifts at the transition thresholds and persist much higher above the AFM Néel temperature. While the MTs exhibit distinctive triaxial anisotropy, reflecting divergent magnetocrystalline anisotropy of the c-axis AFM ground state, the resulting FiM phase has an a-c easy plane in which the magnetization axis is freely rotated by H. At the 2D limit, such a field-tunable FiM phase may provide unique opportunities to explore exotic emergent phenomena and novel spintronicsdevices.

Metamagnetic Transitions and Magnetocaloric Properties of HoCr1-xFexO3 (x = 0.25 and 0.75) Compounds

Metamagnetic Transitions and Magnetocaloric Properties of HoCr1-xFexO3 (x = 0.25 and 0.75) Compounds

Metamagnetic effect in selected MnMg ferrite

A few studies are available on MnMg ferrites, but there is missing information about these ferrites from the point of view of metamagnetic nature. Therefore, in the present study, we have focused on metamagnetic properties of selected MnMg ferrite. The magnetic properties of ferrites having the formula Mn0·894Mg0·347Fe1·758O3.88 prepared by the ceramic technique have been studied. Magnetic measurement has been carried out for examined compound from low magnetic field up to critical field intensity 580 A/m. The composition indicated metamagnetic nature below critical field intensity. In adequate low applied field the formation and increasing of magnetic induction with temperature is caused by changes from canted triangular model to two sublattices model of ferrimagnetic spinel structure. This suggests the existence of canted spin structure in the MnMg ferrite system. Ferrimagnetic properties have been measured by hysteresis loop tracer technique for wide scale of temperatures. Barkhausen noise analysis demonstrated that the magnetizing is prevalently possessed with mechanism of the domain walls motion.

Phase diagram of CeSb2 from magnetostriction and magnetization measurements: Evidence for ferrimagnetic and antiferromagnetic states

Cerium diantimonide ($\mathrm{Ce}{\mathrm{Sb}}_{2}$) is one of a family of rare-earth-based magnetic materials that exhibit metamagnetism, enabling control of the magnetic ground state through an applied magnetic field. At low temperatures, $\mathrm{Ce}{\mathrm{Sb}}_{2}$ hosts a rich phase diagram with multiple magnetically ordered phases for many of which the order parameter is only poorly understood. In this paper, we report a study of its metamagnetic properties by scanning tunneling microscopy (STM) and magnetization measurements. We use STM measurements to characterize the sample magnetostriction with subpicometer resolution from magnetic field and temperature sweeps. This allows us to directly assess the bulk phase diagram as a function of field and temperature and relate spectroscopic features from tunneling spectroscopy to bulk phases. Our magnetostriction and magnetization measurements indicate that the low-temperature ground state at zero field is ferrimagnetic. Quasiparticle interference mapping shows evidence for a reconstruction of the electronic structure close to the Fermi energy upon entering the magnetically ordered phase.

Metamagnetic properties in Mn0.7Mg0.3Fe2O4 ferrite

The paper deals with metamagnetic behaviour of the MnMg ferrites with stoichiometric composition Mn0.7Mg0.3Fe2O4 and is focused to structural nature of found effects. The results are a part of the materials research concerning the relationship between the types of the change from antiferomagnetic (AFM) state to ferrimagnetic (FM) state under the influence of temperature at selected magnetic field. In lower applied field under the critical value of strength Hac the increase in magnetic induction B with temperature is attributed to transition from Yafet-Kittel model to Néel's two-sublattices one. Various evaluation methods, such as e.g. thermo-magnetic analysis, magnetic Barkhausen noise analysis, and X-ray diffraction were used for obtaining experimental data. Magnetic Barkhausen noise analysis showed that mainly the domain-wall motion processes take place in the examined MnMg system.

Metamagnetism in manganate magnesium ferrite

Abstract The metamagnetic properties of the manganese magnesium ferrites having the general formula Mn0.7Mg0.3Fe2O4 prepared by the standard ceramic technique have been studied. It is proposed that when a change of temperature at adequate magnetic field is applied in a Mn0.7Mg0.3Fe2O4 a magnetic phase transition will be generated, giving rise to an antiferromagnetic (AFM) state from ferrimagnetic (FM) phase. The critical transition field H ac = 300 A/m was estimated for critical magnetization curve of transition from the metamagnetic behavior to FM behavior of sample. The FM to AFM transition in these ferrites is accompanied by a Néel type to Yafet-Kittel type transition and gradual spin ordering changes of the unit cell volume. The application of an external magnetic field to the low-temperatures AFM state causes the sample to reset to the original FM state.

Temperature dependence of nonlinear susceptibilities in an infinite range interaction model

We present a model to probe metamagnetic properties in systems with a variable number of interacting spins. Thermodynamic properties such as the magnetization per particle , linear susceptibility , and nonlinear susceptibilities and were calculated. The model produces a different magnetic response for N particles when comparing to N − 1 particles for small . For an even number of particles, the susceptibilities show maxima in their temperature dependence. An odd number produces an additional free spin response that dominates at low temperatures. This free spin response also produces a step in the field-dependent magnetization per particle at B = 0 for odd N. The magnetization shows N/2 steps at with integer n for even N and additional steps at with integer n for odd N. Small clusters respond with metamagnetism in an otherwise isotropic spin space, while the large clusters show no metamagnetism.

Magnetocaloric effect, thermal conductivity, and magnetostriction of epoxy-bonded La(Fe0.88Si0.12)13 hydrides

Magnetic materials with large magnetocaloric effect are significantly important for magnetic refrigeration. La(Fe0.88Si0.12)13 compounds are one of the promising magnetocaloric materials that have a first order magnetic phase transition. Transition temperature of hydrogenated La(Fe0.88Si0.12)13 increased up to room temperature region while keeping metamagnetic transition properties. From view point of practical usage, bonded composite are very attractive and their properties are important. We made epoxy bonded La(Fe0.88Si0.12)13 hydrides. Magnetocaloric effect was studied by measuring specific heat, magnetization, and temperature change in adiabatic demagnetization. The composite had about 20% smaller entropy change from the hydrogenated La(Fe0.88Si0.12)13 powder in 2 T. Thermal conductivity of the composite was several times smaller than La(Fe,Si)13. The small thermal conductivity was explained due to the small thermal conductivity of epoxy. Thermal conductivity was observed to be insensitive to magnetic field in 2 T. Thermal expansion and magnetostriction of the composite material were measured. The composite expanded about 0.25% when it entered into ferromagnetic phase. Magnetostriction of the composite in ferromagnetic phase was about 0.2% in 5 T and much larger than that in paramagnetic phase. The composite didn’t break after about 100 times magnetic field changes in adiabatic demagnetization experiment even though it has magnetostriction.

Tuning the metamagnetic transition in the (Co, Fe)MnP system for magnetocaloric purposes

The inverse magnetocaloric effect taking place at the antiferro-to-ferromagnetic transition of (Co,Fe)MnP phosphides has been characterised by magnetic and direct ΔTad measurements. In Co0.53Fe0.47MnP, entropy change of 1.5 Jkg−1 K−1 and adiabatic temperature change of 0.6 K are found at room temperature for an intermediate field change (ΔB = 1 T). Several methods were used to control the metamagnetic transition properties, in each case, a peculiar splitting of the antiferro-to-ferromagnetic transition is observed.

Study of ferromagnetic correlations caused by impurities in nonmagnetic materials by the method of small-angle scattering of polarized neutrons

The possibility of the study of ferromagnetic correlations caused by d-metal impurities in nonmagnetic matrices is discussed. The polarization and magnetic-nuclear interference obtained by analyzing the small-angle scattering of polarized neutrons in a CuZn(20) alloy with Ni impurity (1 at %) are reported. It has been shown that Ni is clustered in the CuZn matrix with the characteristic correlation radius in the range 100 A < Rc < 5000 A depending on the thermal processing of the samples. The cross correlation function determining magnetic-nuclear interference is satisfactorily approximated by the exponential exp(−r/Rc), where r is the distance. It has been found that the nonmagnetic matrix CuZn(20) with an almost uniform distribution of 1% Ni impurity has metamagnetic properties in the field H ≈ 0.5 T at room temperature.

Mn(II)-Based Porous Metal–Organic Framework Showing Metamagnetic Properties and High Hydrogen Adsorption at Low Pressure

A Mn(II)-based homometallic porous metal-organic framework, Mn(5)(btac)(4)(μ(3)-OH)(2)(EtOH)(2)·DMF·3EtOH·3H(2)O (1, btac = benzotriazole-5-carboxylate), has been solvothermally synthesized and structurally characterized by elemental analysis, thermogravimetric analysis, and X-ray crystallographic study. 1 is a 3D neutral framework featuring 1D porous channels constructed by {Mn-OH-Mn}(n) chains and btac linkers. Magnetic studies show that 1 is a 3D metamagnet containing 1D {Mn-OH-Mn}(n) ferrimagnetic chains. High-pressure H(2) adsorption measurement at 77 K reveals that activated 1 can absorb 0.99 wt % H(2) at 0.5 atm and reaches a maximum of 1.03 wt % at 5.5 atm. The steep H(2) absorption at lower pressure (98.2% of the storage capacity at 0.5 atm) is higher than the corresponding values of some MOFs (MIL-100 (16.1%), MOF-177 (57.1%), and MOF-5 (22.2%)). Furthermore, activated 1 can adsorb CO(2) at room temperature and 275 K. The adsorption enthalpy is 22.0 kJ mol(-1), which reveals the high binding ability for CO(2). Detailed gas sorption implies that the exposed Mn(II) coordination sites in the activated 1 play an important role to improve its adsorption capacities.

LDA + slave‐boson approach to the correlated electronic structure of the metamagnetic bilayer ruthenate Sr3Ru2O7

AbstractThe combination of the local‐density approximation (LDA) with the rotationally invariant slave‐boson theory (RISB) is used to investigate the realistic correlated electronic structure of Sr3Ru2O7. From Wannier‐downfolding the low‐energy band structure to a three‐band model for the Ru(t2g) states, the interacting problem is solved including intra‐ and inter‐orbital Hubbard terms as well as spin‐flip and pair‐hopping interactions. Therewith it is possible to obtain valuable insight into the orbital occupations, relevant local spin multiplets, and the fermiology with increasing correlation strength. Besides generic correlation‐induced band‐narrowing and ‐shifting, an intriguing quasiparticle structure close to the Fermi level is found in the neighborhood of the notorious γ2 pocket in the Brillouin zone. Along the Γ–X direction in k‐space, that structure appears very sensitive to electronic self‐energy effects. The subtle sensitivity, connected also to its manifest multi‐orbital character, may put this very low‐energy structure in context with the puzzling metamagnetic properties of the compound.

Metamagnetic Shape Memory Effect and Magnetic Properties of Ni-Mn Based Heusler Alloys

In some Ni-Mn-In- and Ni-Mn-Sn-based Heusler-type alloys, martensitic transformation from the ferromagnetic parent phase to the paramagnetic martensite phase appears and magnetic field-induced reverse transformation, namely, metamagnetic phase transition, is detected. In this paper, the metamagnetic shape memory effect due to the metamagnetic phase transition and the magnetostress effect in the Ni-Co-Mn-In alloys are introduced and the phase diagrams of Ni50Mn50-yXy (X: In, Sn, Sb) alloys are shown as basic information. Furthermore, the magnetic properties of both the parent and martensite phases in the Ni-Mn-In- and Ni-Mn-Sn-based metamagnetic shape memory alloys are also reviewed.

Effect of the introduction of H atoms on magnetic properties and magnetic entropy change in metamagnetic Heusler alloys Ni–Mn–In

By hydrogen insertion into Ni51Mn49−xInx (x=16.2,16.6) Heusler alloys, the interstitial compounds Ni51Mn49−xInxHδ were fabricated. The introduction of H atoms does not change the L21 structure of the alloys but shifts martensitic temperature (TM) to lower temperature. Magnetic measurements indicated the hydrogenated Ni51Mn49−xInxHδ compounds retain the metamagnetic properties although the ferromagnetic behavior of martensitic phases is slightly enhanced due to the introduction of H atoms. The strong metamagnetic behaviors result in large magnetocaloric effect (MCE). By controlling H content an extended temperature range having large MCE can be achieved.

Magnetic order in the double-layer manganites(La1−zPrz)1.2Sr1.8Mn2O7: Intrinsic properties and role of intergrowth

We report on an investigation of the double-layer manganite series (La(1-z)Pr(z))1.2Sr1.8Mn2O7 (0 = 0.6), while more moderate Pr substitutions (0.2 <= z <= 0.4) induce a spin reorientation transition within the ferromagnetic phase. A large magnetic susceptibility is detected at {Tc,TN} < T < 250K at all compositions. From 55Mn NMR spectroscopy, such a response is unambiguously assigned to the intergrowth of a ferromagnetic pseudocubic phase (La(1-z)Pr(z))(1-x)Sr(x)MnO3, with an overall volume fraction estimated as 0.5-0.7% from magnetometry. Evidence is provided for the coupling of the magnetic moments of these inclusions with the magnetic moments of the surrounding (La(1-z)Pr(z))1.2Sr1.8Mn2O7 phase, as in the case of finely dispersed impurities. We argue that the ubiquitous intergrowth phase may play a role in the marked first-order character of the magnetic transition and the metamagnetic properties above Tc reported for double-layer manganites.

IrSr 2TbCu 2O 8, a high-pressure metamagnetic cuprate: Structure, microstructure and properties

The synthesis, structure and microstructure of the IrSr 2TbCu 2O 8 cuprate showing metamagnetic properties are described. The sample was prepared at high temperatures and pressures up to 9.2 GPa. The structure is tetragonal, showing a 1212 type structure, that derives from the classical YBaCuO superconductor structure, replacing the tetracoordinated square planar copper [Cu–O 4] in the “chains” by octahedral [Ir–O 6] groups that form a perovskite-like layer in the basal plane of the unit cell. A “simple” cell, ∼ a p× a p×3 a p, where a p is the basic perovskite unit cell parameter ( a p∼3.8 Å), is supported by X-ray powder diffraction (XRD) and a so-called “diagonal” one, ∼√2 a p×√2 a p×3 a p, by SAED; a microdomain texture of latter cell and a series of very interesting extended defects have been observed by HREM. Magnetic susceptibility measurements show a magnetic transition, T N∼6 K, with negative Weiss temperature, that indicates antiferromagnetic interactions among the Tb moments. The magnetic structure has been determined by neutron diffraction. A detailed magnetic study has revealed a metamagnetic behavior, something not previously observed in this type of cuprates. Specific heat and resistivity measurements have also been performed to characterize the transition.

Structural Chemistry and Metamagnetism of an Homologous Series of Layered Manganese Oxysulfides

An homologous series of layered oxysulfides Sr2MnO2Cu(2m-delta)S(m+1) with metamagnetic properties is described. Sr2MnO2Cu(2-delta)S2 (m = 1), Sr2MnO2Cu(4-delta)S3 (m = 2) and Sr2MnO2Cu(6-delta)S4 (m = 3), consist of MnO2 sheets separated from antifluorite-type copper sulfide layers of variable thickness by Sr(2+) ions. All three compounds show substantial and similar copper deficiencies (delta approximately equal to 0.5) in the copper sulfide layers, and single-crystal X-ray and powder neutron diffraction measurements show that the copper ions in the m = 2 and m = 3 compounds are crystallographically disordered, consistent with the possibility of high two-dimensional copper ion mobility. Magnetic susceptibility measurements show high-temperature Curie-Weiss behavior with magnetic moments consistent with high spin manganese ions which have been oxidized to the (2+delta)+ state in order to maintain a full Cu-3d/S-3p valence band, and the compounds are correspondingly p-type semiconductors with resistivities around 25 Omega cm at 295 K. Positive Weiss temperatures indicate net ferromagnetic interactions between moments. Accordingly, magnetic susceptibility measurements and low-temperature powder neutron diffraction measurements show that the moments within a MnO(2) sheet couple ferromagnetically and that weaker antiferromagnetic coupling between sheets leads to A-type antiferromagnets in zero applied magnetic field. Sr2MnO2Cu(5.5)S4 and Sr2MnO2Cu(3.5)S3 are metamagnets which may be driven into the fully ordered ferromagnetic state below 25 K by the application of fields of 0.06 and 1.3 T respectively. The relationships between the compositions, structures, and physical properties of these compounds, and the prospects for chemical control of the properties, are discussed.

One-Dimensional Ferromagnetic Complexes Built with MnIII3O Units

Two chain complexes built with non-carboxylate Mn(III)3O units, [Mn3O(ppz)3(MeOH)3(OAc)]n (1) and [Mn3O(Meppz)3(MeOH)4(OAc)]n (2), were synthesized and characterized. Magnetic studies revealed similar intrachain ferromagnetic interactions in them and field-induced metamagnetic properties in 1.

Antiferromagnetism in the ordered subsystem of Cr ions intercalated into titaniumdiselenide

The results of crystal structure, bulk magnetic properties and magneticstructure investigations are reported for the intercalated compoundCr0.5TiSe2. The Cr atoms are found to be ordered in the hexagonalTiSe2 matrix forming a superlattice , b = a′, c = 2c′. The first neutron diffraction measurements performed for this compoundtogether with susceptibility and magnetization data have shown that thiscompound exhibits a complex incommensurate magnetic structure belowTN = 42 K. This structure is suggested to arise from the competition between the ferromagneticexchange interaction dominating mainly within the Cr layers and antiferromagneticinterlayer exchange. Because of weakness of the interlayer exchange in comparison withintralayer one this compound exhibits metamagnetic properties.

Magnetic properties of compounds in the system CaBaCo4−x−yZnxAlyO7 (x=0,1,2, y=0,1)

The magnetic properties of four compounds in the series CaBaCo4−x−yZnxAlyO7 (x=0,1,2, y=0,1) were investigated. Using AC-susceptibility and DC-magnetometry, magnetic transitions (Tfs) were found for all four compositions in the range 50–3K. The data from the AC measurements proved to be frequency dependent: Tf increases with higher frequencies. An energy-loss in the magnetic coupling, indicated as contributions in the imaginary part of the magnetic susceptibility (χ″), was seen for every compound and its maximum appeared just below the maximum χ′. Modelling the data with Arrhenius-, Vogel–Fulcher-, and the power-law made it possible to relate the four compounds to spin-glass materials. The Casimir-du Pré relation was used to extract average relaxation times at Tf. The DC magnetisations clearly show differences between field-cooled and zero-field-cooled measurements. None of the compounds exhibit any metamagnetic properties up to 8T. A new method is presented to calculate the saturation fields using DC data. Relaxation measurements on three compounds indicate that the systems relax very fast, in contrast to spin-glasses. Aging does not affect the fast relaxations. The compounds are interpreted as disordered anti-ferromagnets with spin-glass features.