Short-range Magnetic Order Research Articles

Time-resolved magneto-optical effects in the altermagnet candidate MnTe

α -MnTe is an antiferromagnetic semiconductor with above room temperature TN = 310 K, which is promising for spintronic applications. Recently, it was reported to be an altermagnet, containing bands with momentum-dependent spin splitting; time-resolved experimental probes of MnTe are, therefore, important both for understanding novel magnetic properties and potential device applications. We investigate ultrafast spin dynamics in epitaxial MnTe(001)/InP(111) thin films using pump-probe magneto-optical measurements in the Kerr configuration. At room temperature, we observe an oscillation mode at 55 GHz that does not appear at zero magnetic field. Combining field and polarization dependence, we identify this mode as a magnon, likely originating from inverse stimulated Raman scattering. Magnetic field-dependent oscillations persist up to at least 335 K, which could reflect coupling to known short-range magnetic order in MnTe above TN. Additionally, we observe two optical phonons at 3.6 and 4.2 THz, which broaden and redshift with increasing temperature.

Magnetic excitation in the hyperkagome antiferromagnet Mn3RhSi

In a paramagnetic state of a hyperkagome lattice antiferromagnet Mn3RhSi, magnetic diffuse scattering by magnetic short-range order is observed over a wide temperature range of approximately 500 K above the Néel temperature of 190 K. We have studied the magnetic excitation with a single crystal in a wide energy range from 0.3 to 140 meV by inelastic neutron scattering, where the prominent inelastic neutron-scattering signal is observed at Q=(2,0,0). The inelastic scattering intensity integrated for two of twelve magnon modes leads to a localized magnetic moment of about 5 μB per Mn site, although the long-range ordered magnetic moment is only 2.61 μB at 4 K. The result suggests that a large part of the magnetic moment does not order in Mn3RhSi, possibly due to the geometrical spin frustration of the hyperkagome lattice. Published by the American Physical Society 2024

Self-Stacked 1T-1H Layers in 6R-NbSeTe and the Emergence of Charge and Magnetic Correlations Due to Ligand Disorder.

The emergence of correlated phenomena arising from the combination of 1T and 1H van der Waals layers is the focus of intense research. Here, we synthesize a self-stacked 6R phase in NbSeTe, showing perfect alternating 1T and 1H layers that grow coherently along the c-direction, as revealed by scanning transmission electron microscopy. Angle-resolved photoemission spectroscopy shows a mixed contribution of the trigonal and octahedral Nb bands to the Fermi level. Diffuse scattering reveals temperature-independent short-range charge fluctuations with propagation vector qCO = (0.25 0), derived from the condensation of a longitudinal mode in the 1T layer, while the long-range charge density wave is quenched by ligand disorder. Magnetization measurements suggest the presence of an inhomogeneous, short-range magnetic order, further supported by the absence of a clear phase transition in the specific heat. These experimental analyses in combination with ab initio calculations indicate that the ground state of 6R-NbSeTe is described by a statistical distribution of short-range charge-modulated and spin-correlated regions driven by ligand disorder. Our results demonstrate how natural 1T-1H self-stacked bulk heterostructures can be used to engineer emergent phases of matter.

A systematic study of oxygen vacancy mediated short range and long range magnetic ordering in BaTi1-xFexO3(x = 0.02)

A systematic study on the magnetic properties of the BaTi1-xFexO3-δ (x = 0.02) system with decrease in grain sizes is presented. The combined study of long range and short range magnetic orderings together was carried out. The samples were prepared in single tetragonal phase. The grains of the pristine sample were refined from micron to nanometer range by mechanical milling. Oxygen vacancies in different charge states gave rise to ferromagnetic and antiferromagnetic orderings among the Fe3+ ions whereas oxygen atoms acted as the medium for antiferromagnetic superexchange among the Fe3+ ions. Magnetization was found to increase significantly as a result of milling and eventually the saturation magnetization became four-fold in the sample with grain size around 18 nm. The increase in magnetization is attributed to the increase in oxygen vacancies as a consequence of increase in milling time. Clear sextet patterns in the Mössbauer spectra were observed in the sample wherein 57Fe–enriched iron was used in place of natural iron. These sextets were attributed to the presence of FM and AFM orderings among Fe3+ ions. Along with the sextet patters, we also observed a doublet pattern in Mössbauer spectra because of quadrupolar interaction of the isolated Fe3+ ions arranged in non-cubic environment and lacking any kind of magnetic interactions among them. Mössbauer Spectroscopic (MS) study revealed that FM ordering increased while AFM ordering disappeared after milling. Drastic fall of coercivity in samples with grain sizes below around 40 nm indicated that they became single magnetic domain.

Complex magnetic interactions and critical behavior analysis in quaternary CoFeV0.8Mn0.2Si Heusler alloy

We investigate the magnetic behavior and critical exponents of quaternary CoFeV0.8Mn0.2Si Heusler alloy to understand the interactions across the Curie temperature (TC). The Rietveld refinement of the x-ray diffraction pattern with the space group F4¯3m confirms a single-phase cubic Y-type crystal structure. The magnetic susceptibility χ(T) data show a ferromagnetic nature with a second-order phase transition from paramagnetic to ferromagnetic at 446±1 K. The saturation magnetization at 5 K is found to be 2.2 μB/f.u., which is close to the Slater–Pauling rule and indicates its half-metallic nature. The values of asymptotic critical exponents (β, γ, and δ) and the TC are extracted through detailed analytical analysis including the modified Arrott plot, the Kouvel–Fisher (K–F) method, and the Widom scaling relation. Interestingly, the estimated values of β=0.369 and γ=1.445 closely approximate the theoretical values of the 3D Heisenberg model across the TC and validate the second-order thermodynamic phase transition. The obtained exponents lead to the collapse of renormalized isotherms, represented by the relationship between the magnetization (m) and the applied magnetic field (h), into two distinct branches above and below the TC, which validates the reliability of the analysis. Furthermore, these exponents suggest that the spin interaction follows a decay pattern of J(r)∼r−4.99, indicating a short-range magnetic ordering, akin to the itinerant-electron 3D Heisenberg model.

Quantum critical behavior of the hyperkagome magnet Mn3CoSi

β-Mn-type family alloys Mn3TX (T=Co, Rh, and Ir; X=Si and Ge) have a three-dimensional antiferromagnetic (AF) corner-shared triangular network, i.e., the hyperkagome lattice. The antiferromagnet Mn3RhSi shows magnetic short-range order over a wide temperature range of approximately 500 K above the Néel temperature TN of 190 K. In this family of compounds, as the lattice parameter decreases, the long-range magnetic ordering temperature decreases. Mn3CoSi has the smallest lattice parameter and the lowest TN in the family. The quantum critical point (QCP) from AF to the quantum paramagnetic state is expected near a cubic lattice parameter of 6.15 Å. Although the Néel temperature of Mn3CoSi is only 140 K, the emergence of the quantum critical behavior in Mn3CoSi is discussed. We study how the magnetic short-range order appears in Mn3CoSi by using neutron scattering, μSR, and bulk characterization such as specific heat capacity. According to the results, the neutron scattering intensity of the magnetic short-range order in Mn3CoSi does not change much at low temperatures from that of Mn3RhSi, although the μSR short-range order temperature of Mn3CoSi is largely suppressed to 240 K from that of Mn3RhSi. Correspondingly, the volume fraction of the magnetic short-range order regions, as shown by the initial asymmetry drop ratio of μSR above TN, also becomes small. Instead, the electronic-specific heat coefficient γ of Mn3CoSi is the largest in this Mn3TSi system, possibly due to the low-energy spin fluctuation near the quantum critical point. Published by the American Physical Society 2024

The effect of the gelation temperature on the structural, magnetic and magnetocaloric properties of perovskite nanoparticles manufactured using the sol-gel method.

This study presents a comprehensive investigation of the structural and magnetic properties of La0.8Sr0.2Mn0.8Co0.2O3 (LS1, LS2 and LS3) compounds synthesized via the sol-gel method at different gelation temperatures through X-ray diffraction and different magnetic measurement techniques. The Rietveld refinement demonstrated that all samples exhibit a rhombohedral perovskite structure with the R3̄C space group. Their magnetic behavior, characterized through magnetization measurements, hysteresis loops, and Arrot plots, demonstrates a ferromagnetic-paramagnetic transition with notable soft ferromagnetic characteristics. The samples also demonstrate second-order magnetic transitions, short-range magnetic order and the presence of both ferromagnetic and antiferromagnetic contributions. AC magnetic susceptibility measurements, allowing the investigation of the magnetic dynamics of the samples, shows that the Vogel-Fulcher and the Conventional Critical Slowing Down models are the most appropriate for describing the dynamic behavior, confirming the spin-glass nature of the compounds and the presence of medium to strong interaction between magnetic nanoparticles. The influence of gelation temperature in the magnetocaloric effect of the compounds was proven and LS1, synthesized at the lowest gelation temperature (70 °C), exhibits the higher magnetic entropy change (|ΔSmax| = 3.25 J kg-1 K-1 and RCP = 209.83 J kg-1 at 5 T). For a better evaluation of the magnetocaloric efficiency, the temperature average entropy change (TEC) parameter was calculated for all three samples and LS1 showed the highest value (TEC (LS1) ∼3.2 J kg-1 K-1 for ΔTH-C = 10 K and ΔH = 5 T).

Effect of Al substitution at the Ga site on the structural and magnetic properties of GaFeO3

GaFeO3 compound figures among those orthoferrites that are potential candidates for multiferroics. However, GaFeO3 suffers from a relatively low Nèel temperature, TN ≈ 200 K, and magnetic moment. Based on the results of a detailed investigation of Raman-active modes, structural and magnetic properties of the Ga1-xAlxFeO3 (x = 0.0, 0.05, 0.10, 0.20, 0.30) samples, we show that Al substitution at the Ga sites remedies these shortcomings to a large extent. This work brings out clearly that Al preferentially occupies the tetrahedral (Ga1) sites rather than the octahedral (Ga2, Fe1 and Fe2) sites. The effect of Al substitution in Ga1-xAlxFeO3 is to (i) decrease the lattice parameters and cation-O bond lengths which results in a shift in the positions of Raman peaks towards higher wavenumbers, and (ii) increase (decrease) the cation-O-cation bond-angles such that the antiferromagnetic (ferromagnetic) superexchange interactions grow in strength. An enhancement in these interactions accounts for the observed increase in the Nèel temperature, TN, as well as in the saturation magnetization. The radically different temperature variations of the ‘zero-field-cooled’ and ‘field-cooled’ magnetizations below the irreversibility temperature can be qualitatively understood in terms of the Nèel molecular-field theory for ferrimagnetism. The temperature dependence of inverse susceptibility in the paramagnetic state provides evidence for the non-linear behavior at temperatures well above TN and hence for the persistence of short-range magnetic order to temperatures as high as 1.75 TN.

Modulation of magnetic and dielectric properties by Al3+ substitution in Ca3CoMnO6 ceramics

We report a detailed study of the influence of non-magnetic Al3+ doping on the microstructure, magnetic, and dielectric characteristics Ca3CoMnO6. The introduction of Al3+ leads to the suppression of competing short-range magnetic orders, a gradual disappearance of the spin freezing peak in Ca3CoMn1-xAlxO6 was observed, accompanied by the release of magnetic frustration. Moreover, a weakening of the antiferromagnetic order in Ca3CoMnO6 was attributed to the dilution effect induced by non-magnetic Al3+ within the Co-Mn-Co-Mn spin chains. The dielectric measurements exhibit excellent agreement with the magnetic measurements. The substitution of Mn4+ with Al3+ results in the attenuation of relaxor ferroelectric behavior, accompanied by a decrease in the static freezing temperature Tf and an increase in the activation energy Ea. It indicates that Al3+ substitution could well suppress the formation of polar nanoregions. With introducing Al3+ the magnetodielectric effect of Ca3CoMnO6 is also significantly enhanced. For the x = 0.15 sample, the magnetodielectric effect undergoes a notable variation of approximately 10 % under a magnetic field of H = 4 T.

High-pressure syntheses, crystal structures, and magnetic properties of novel quadruple perovskite oxides LaMn3Ru2Mn2O12 and LaMn3Ru2Fe2O12

Quadruple perovskite oxides LaMn3Ru2M2O12 (M = Mn, Fe) have been synthesized under high-pressure and high-temperature conditions of 8 GPa and 1373 K. Synchrotron X-ray powder diffraction study demonstrates that both oxides crystallized in AA'3B4O12-type cubic quadruple perovskite structures, where the Ru and M ions did not form the special ordering at B-site. X-ray absorption spectroscopy reveals that the valence states are represented as LaMn3+3Ru3+2M3+2O12 (M = Mn, Fe) in the ionic models, indicating that the isovalent states of Ru3+ and M3+ ions disturb the B-site ordering. Magnetization, heat capacity, and neutron diffraction data prove that short-range magnetic orderings are predominant for both compounds instead of long-range magnetic orderings. We conclude that the competition between ferromagnetic and antiferromagnetic superexchange interactions between Ru3+ and M3+ ions at B-site prevent the long-range magnetic ordering Mn3+ ions at A′-site, although the A'- and B-site magnetic sublattices are expected to be intrinsically independent in A′-Mn quadruple perovskite system. This finding represents that the atomic ordering of the B-site is essential for the precise design of magnetic structures for the LaMn3M2M′2O12 quadruple perovskite series.

Spiral spin cluster in the hyperkagome antiferromagnet Mn3RhSi

Local spin correlation orders emerge in a paramagnetic state, with notable examples such as the partial order, cooperative paramagnetism, and soliton spin liquid. The noncentrosymmetric intermetallic antiferromagnet Mn3RhSi also exhibits the local spin correlation order in the paramagnetic state as magnetic short-range order in a wide temperature range. Here, we show that the local spin correlation order has a spiral structure by neutron scattering measurement of a Mn3RhSi single crystal. The possible origins of the magnetic cluster formation are discussed in terms of the Lifshitz invariant and the Griffiths phase, and compared with the room-temperature skyrmion phase of Co7Zn7Mn6 and non-Fermi liquid behavior of β-Mn.

Hubbard Bands and Exotic States in Doped and Undoped Mott Systems: The Kotliar–Ruckenstein Representation

The slave–particle representation is a promising method to treat the properties of exotic strongly correlated systems. We develop a unified approach to describe both the paramagnetic state with possible spin–liquid features and states with strong long-range or short-range magnetic order. Combining the Kotliar–Ruckenstein representation and fractionalized spin–liquid deconfinement picture, the Mott transition and Hubbard subbands are considered. The spectrum in the insulating state is significantly affected by the presence of the spinon spin–liquid spectrum and a hidden Fermi surface. Presenting a modification of the Kotliar–Ruckenstein representation in the spin–wave region, we treat the case of magnetic order, with special attention being paid to the half-metallic ferromagnetic state. The formation of small and large Fermi surfaces for doped current carriers in the antiferromagnetic state is also discussed.

The in- and out-of-plane magnetisation of highly underdoped YBa2Cu3O6+x single crystals

Previously we have shown how measurements of static magnetic susceptibility χc(T) of YBa2Cu3O6+x single crystals for magnetic fields applied along the c-axis, and χab(T) for fields in the ab-plane, can give useful information about their thermodynamic properties which are still being hotly debated. SQUID magnetometry above the superconducting (s/c) transition temperature Tc is used for larger crystals, while piezolever torque magnetometry gives χc(T)-χab(T) for tiny crystals. Here we present new data for more heavily under-doped crystals with hole concentrations per CuO2 plane, p =0.058 to 0.073. We again find that the T-dependent anisotropy well above Tc arises from the pseudogap and the g-factor anisotropy, while at lower T there are Gaussian s/c fluctuations with a strong cut-off. This is possibly a different region where neutron scattering studies give evidence for competition between incommensurate magnetic short-range order and superconductivity. We have studied crystals with three values of x, measuring χc(T) and χab(T) immediately after fixing x by quenching on to a copper block and again after allowing sufficient time at room temperature for the Cu-O chains to order. Thus, we report data for three pairs of underdoped (UD) crystals with Tc ranging from 13 to 36 K, namely UD13 and UD20, UD15 and UD30, UD23 and UD36. As found previously for polycrystalline samples, ordering the Cu-O chains increases Tc and substantially reduces the Curie term. These are isotropic, in contrast to the Pauli-like susceptibility from the CuO2 planes where there is g factor anisotropy, and this allows us to make a powerful novel analysis. At higher T, χc(T)- χab(T) varies as a + bT where the bT term arises from the pseudogap. At lower T, deviations from this behaviour are analysed in terms of 2D or 3D Gaussian s/c fluctuations to obtain in-plane coherence lengths and upper critical fields as T→0.

Coupling of magnetism, crystal lattice, and transport in EuCuP and EuCuAs

EuCuP and EuCuAs are members of a family of materials with candidates for realizing magnetically tuned electronic topology. In this work, the magnetic phase transitions and magnetoelastic coupling of EuCuP and EuCuAs have been investigated. Around the Curie temperature, the thermal expansion coefficient and specific-heat capacity of EuCuP are found to have two closely spaced features, at approximately 30 and 31.3 K, which may indicate a cascading magnetic transition or perhaps an electronic transition closely coupled to the magnetic ordering. The zero-field magnetoelastic coupling appears to be stronger in EuCuP than in EuCuAs, and field-dependent measurements suggest this is due to the dominant ferromagnetic interaction in EuCuP as opposed to antiferromagnetic order in EuCuAs below ${T}_{\mathrm{N}}=13.5\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. Thermal expansion is anisotropic around ${T}_{\mathrm{N}}$ in EuCuAs, with a maximum expansion along [001] occurring above ${T}_{\mathrm{N}}$ prior to a stiffening of this $c$-axis component on cooling through ${T}_{\mathrm{N}}$; the expansion of the basal plane has a lambda-like peak centered slightly above ${T}_{\mathrm{N}}$. Matching these behaviors, the ac susceptibility data for EuCuAs suggest the presence of strong ferromagnetic correlations above ${T}_{\mathrm{N}}$ in the vicinity where the $c$-axis expansion peaks. Both compounds possess similar electrical and thermoelectric transport behaviors, with short-range magnetic order likely playing an important role above ${T}_{\mathrm{C}}$ or ${T}_{\mathrm{N}}$. Transport properties suggest these are predominantly hole doped due to intrinsic defects, and narrow-gap semiconducting or semimetallic behavior may be achievable if the underlying defects can be tuned.

Room temperature colossal superparamagnetic order in aminoferrocene–graphene molecular magnets

Intensive studies are published for graphene-based molecular magnets due to their remarkable electric, thermal, and mechanical properties. However, to date, most of all produced molecular magnets are ligand based and subject to challenges regarding the stability of the ligand(s). The lack of long-range coupling limits high operating temperature and leads to a short-range magnetic order. Herein, we introduce an aminoferrocene-based graphene system with room temperature superparamagnetic behavior in the long-range magnetic order that exhibits colossal magnetocrystalline anisotropy of 8 × 105 and 3 × 107 J/m3 in aminoferrocene and graphene-based aminoferrocene, respectively. These values are comparable to and even two orders of magnitude larger than pure iron metal. Aminoferrocene [C10H11FeN]+ is synthesized by an electrophilic substitution reaction. It was then reacted with graphene oxide that was prepared by the modified Hammers method. The phase structure and functionalization of surface groups were characterized and confirmed by XRD, FT-IR, and Raman spectroscopy. To model the behavior of the aminoferrocene between two sheets of hydroxylated graphene, we have used density functional theory by placing the aminoferrocene molecule between two highly ordered hydroxylated sheets and allowing the structure to relax. The strong bowing of the isolated graphene sheets suggests that the charge transfer and resulting magnetization could be strongly influenced by pressure effects. In contrast to strategies based on ligands surface attachment, our present work that uses interlayer intercalated aminoferrocene opens routes for future molecular magnets as well as the design of qubit arrays and quantum systems.

Phonon, defect and magnetic contributions to heat capacity of EuxYb1-xB6 solid solutions

Zero-field heat capacity of EuxYb1-xB6 (x = 0, 0.127, 1) family was investigated at temperatures 1.9 − 300 K. The applied procedure of C(T) decomposition allowed to identify the Debye component resulted from the rigid cage of boron atoms (ΘD ≈ 1160 K), as well as the contribution from the quasilocal vibrational modes of rare-earth (RE) ions with Einstein temperatures to be different in end-point compounds: ΘE(YbB6) ≈ 91.6 K and ΘE(EuB6) ≈ 125 K. Our results also suggest the existence of additional low-temperature defect mode for the Eu-low systems (x ≤ 0.127) which is related to ≈ 1.15–1.3% vacancies at boron position. The magnetic contribution for EuB6 was analyzed in the framework of mean-field theory. The estimates show that 97% of spin entropy, associated with the 8S7/2-state of Eu2+ ions, is frozen out at TC. The finding that short-range magnetic ordering in the paramagnetic (PM) phase is limited by no more than 3% of EuB6 spin entropy should be taken into account in modern approaches explaining electronic and magnetic phase separation in this extraordinary compound.

Crystal growth and magnetic properties of the coupled alternating S=1 spin chain Sr2Ni(SeO3)3

The structural, magnetic, and thermodynamic properties of a quasi-one-dimensional (1D) $S=1$ alternating spin chain compound ${\mathrm{Sr}}_{2}\mathrm{Ni}{(\mathrm{Se}{\mathrm{O}}_{3})}_{3}$ are investigated by using synchrotron x-ray powder diffraction, magnetic susceptibility $\ensuremath{\chi}(H,T)$, and heat capacity ${C}_{\mathrm{P}}(H,T)$ measurements together with density functional theory (DFT) calculations. The $\ensuremath{\chi}(H,T)$ and ${C}_{\mathrm{P}}(H,T)$ data reveal long-range antiferromagnetic order at ${T}_{\mathrm{N}}=3.4(3)$ K and short-range order at ${T}_{\mathrm{m}}\ensuremath{\approx}7.8\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. The short-range magnetic order together with 95% of spin entropy release above ${T}_{\mathrm{N}}$ signifies the importance of 1D spin correlations persisting to $\ensuremath{\sim}8{T}_{\mathrm{N}}$. Theoretical DFT calculations with generalized gradient approximation determine leading exchange interactions, suggesting that interchain interactions are responsible for the observed long-range magnetic ordering. In addition, the temperature-field phase diagram of ${\mathrm{Sr}}_{2}\mathrm{Ni}{(\mathrm{Se}{\mathrm{O}}_{3})}_{3}$ is determined based on the $\ensuremath{\chi}(T,H)$ and ${C}_{\mathrm{P}}(T,H)$ data. Interestingly, a nonmonotonic phase boundary of ${T}_{\mathrm{m}}$ is found for an external field applied along a hard axis. Our results suggest that the ground state and magnetic behavior of ${\mathrm{Sr}}_{2}\mathrm{Ni}{(\mathrm{Se}{\mathrm{O}}_{3})}_{3}$ rely on the interplay of single-ion anisotropy, bond alternation, and interchain interactions.

Structural modulation and spin glassiness upon oxidation in oxygen storage material LnFeMnO4+x for Ln = Y, Lu, and Yb

The mixed valence multiferroic LnFe2+Fe3+O4 (where Ln = Y, Lu, and Yb) can reversibly uptake oxygen into its lattice, which is evidenced by a crystallographic phase transition along with the appearance of structural modulations. In this study, we show that the Mn-substituted version of this multiferroic can also be readily oxidized to LnFe3+Mn3+O4.5 revealing similar oxygen storage behavior. Through neutron, electron, and synchrotron x-ray diffraction studies, we observe a structural modulation that we attribute to a displacement wave in the fully oxidized compound. This wave exhibits commensurability with a wavevector q = (−2/7, 1/7, 0). Bond valence summation analysis of plausible interstitial oxygen positions suggests that oxygen insertion likely occurs at the middle of the Fe/Mn–O bipyramid layers. The structural modulation of LnFeMnO4.5 is two-dimensional, propagates along the ab-plane, and is highly symmetric as 12 identical modulation vectors are observed in the diffraction patterns. The nature of the lanthanide, Ln3+, does not seem to influence such modulations since we observe identical satellite reflections for all three samples of Ln = Y, Lu, and Yb. Both LnFeMnO4 and LnFeMnO4.5 display spin glassy behavior with 2D short-range magnetic ordering being observed in LnFeMnO4. Analysis of the neutron diffraction data reveals a correlation length of ∼10 nm. Upon oxidation to LnFeMnO4.5, the short-range magnetic order is significantly suppressed.

Evidence of Long-Range and Short-Range Magnetic Ordering in the Honeycomb Na3Mn2SbO6 Oxide

We present a comprehensive study of the synthesis, structure, and magnetic properties of the honeycomb oxide Na3Mn2SbO6 supported by neutron diffraction, heat capacity, and magnetization measurements. The refinements of the neutron diffraction patterns (150, 50, and 45 K) using the Rietveld method confirm the monoclinic (S. G. C2/m) structure. Temperature-dependent magnetic susceptibilities measured at varying fields along with the heat capacity measurements demonstrate the coexistence of long-range ordering (∼42 K) and short-range ordering (∼65 K). The field-dependent isothermal magnetization measurements at 5 K indicate a spin-flop transition around 5 T. Rietveld refinements of the low-temperature (below 45 K) neutron diffraction data further confirm the long-range magnetic ordering. In addition, the temperature variation of the lattice parameters obtained from the neutron powder diffraction analysis exhibited a distinct anomaly near the antiferromagnetic transition temperature. The appearance of the concomitant broadened backgrounds in the neutron powder diffraction data collected at 80, 50, and 45 K supports the short-range ordering. The resultant magnetic structure consists of spins that are aligned antiparallel with the nearest neighbors and also with the spins of the adjacent honeycomb layers. The occurrence of a fully ordered magnetic ground state (Neel antiferromagnetic (AFM)) in Na3Mn2SbO6 consolidates the significance of fabricating new honeycomb oxides.

Short-Range Magnetic Order at Low Temperatures, Exchange Bias, and Negative Magnetization in Undoped CuCrO2

Short-Range Magnetic Order at Low Temperatures, Exchange Bias, and Negative Magnetization in Undoped CuCrO2