Canted Antiferromagnetic Structure Research Articles

Unusual magnetic properties of (Sr, Mn)-substituted BiFeO3 near the polar/antipolar phase boundary

Investigations of the crystal structure and magnetic properties of the Bi0.85Sr0.15Fe1-xMnxO3 (0.1 ≤ x ≤ 0.5) ferromanganites were carried out. The materials maintain the single-phase polar R3c structure of the pure bismuth ferrite up to x = 0.35 (a further increase in the Mn content stabilizes the antipolar Pnam phase), thus exhibiting the coexistence of spontaneous polarization and magnetic order over a wide range of Mn concentrations, sufficient to influence the cycloidal antiferromagnetic arrangement typical of the parent compound and contribute to the canted antiferromagnetic phase formation (at room temperature). A complex magnetic behaviour with irregular changes in remanent magnetization and coercive field suggesting the temperature-driven modification of the canted antiferromagnetic structure near the polar/antipolar phase boundary has also been found.

Magnetic structure and crystal field states ofPr2Pd3Ge5:μSRand neutron scattering investigations

We present the results of muon spin relaxation ($\ensuremath{\mu}\mathrm{SR}$), neutron powder diffration (NPD), and inelastic neutron scattering (INS) investigations on polycrystalline ${\mathrm{Pr}}_{2}{\mathrm{Pd}}_{3}{\mathrm{Ge}}_{5}$. The polycrystalline ${\mathrm{Pr}}_{2}{\mathrm{Pd}}_{3}{\mathrm{Ge}}_{5}$ is known to exhibit two antiferromagnetic transitions near ${T}_{\mathrm{N}1}=8.3$ K and ${T}_{\mathrm{N}2}=7.5$ K which is confirmed by the heat capacity measurements on the present sample. In the magnetically ordered state the NPD data show clear evidence for magnetic Bragg peaks, which for $T<{T}_{\mathrm{N}2}$ could be indexed with a propagation vector k = (1, 0, 0), and with k = (1, 0, 0.07) for ${T}_{\mathrm{N}2}<T<{T}_{\mathrm{N}1}$. We have determined the magnetic structure and found a canted antiferromagnetic structure of ordered ${\mathrm{Pr}}^{3+}$ moments. At 7.6 K we find an amplitude modulated incommensurate antiferromagnetic arrangement of ordered moments with a maximum ordered moment of 1.64(3) ${\ensuremath{\mu}}_{\mathrm{B}}$/Pr lying in the $ab$ plane tilted at about ${26}^{\ensuremath{\circ}}$ from the $b$ axis. At 1.8 K the antiferromagnetic structure is found to be commensurate with an ordered moment of 2.80(6) ${\ensuremath{\mu}}_{\mathrm{B}}$/Pr lying in the $ab$ plane tilted at about ${28}^{\ensuremath{\circ}}$ from the $b$ axis. Our zero-field $\ensuremath{\mu}\mathrm{SR}$ spectra at 1.5 K and at shorter time scale (below 0.5 $\ensuremath{\mu}\mathrm{s}$) reveal two oscillatory frequencies further supporting a long-range-ordered magnetic ground state. We have calculated the muon sites using the density functional theory calculation and present the results of internal field calculations at the muon stopping sites, which are in good agreement with the experimental observations. In the paramagnetic state, the INS data show three well defined CEF excitations near 8.0, 12.3, and 18.1 meV arising from the crystal electric field (CEF) split $J=4$ ground state of ${\mathrm{Pr}}^{3+}$. The CEF level scheme is deduced by analyzing the INS data by a model based on the CEF model.

Magnetotransport as a probe for the interplay between Sm and Fe magnetism in SmFeAsO

The complex magnetic ordering of parent compounds of most unconventional superconductors is crucial for the understanding of high-temperature superconductivity (SC). Within this framework, we have performed temperature-dependent magnetotransport experiments on a single crystal of SmFeAsO, a parent compound of iron pnictide superconductors. We observe multiple features in the measured transport properties at temperatures below the antiferromagnetic (AFM) ordering of Sm, , which evolve with in-plane magnetic field, suggesting a rich variety of metamagnetic transitions never before observed in this compound. Considering that transport mainly involves Fe d orbitals at the Fermi level, these findings suggest that the features originate from magnetic transitions of the Fe moments sublattice, which in turn may be induced by magnetic transitions of the Sm moments sublattice via the interaction between Fe and Sm moments. We outline a possible scenario in which the Fe moments, strongly affected by the Sm ordering below T NSm, reorder to an in-plane canted AFM structure, which is washed out by the application of an in-plane magnetic field up to 9 T. Our work shows that transport properties are a valuable tool for investigating magnetic ordering in iron pnictide parent compounds, where the interplay of magnetism and SC is believed to be the origin of high-temperature SC.

Spin structure and dynamics of the topological semimetal Co3Sn2-xInxS2

The anomalous Hall effect (AHE), typically observed in ferromagnetic (FM) metals with broken time-reversal symmetry, depends on electronic and magnetic properties. In Co3Sn2-xInxS2, a giant AHE has been attributed to Berry curvature associated with the FM Weyl semimetal phase, yet recent studies report complicated magnetism. We use neutron scattering to determine the spin dynamics and structures as a function of x and provide a microscopic understanding of the AHE and magnetism interplay. Spin gap and stiffness indicate a contribution from Weyl fermions consistent with the AHE. The magnetic structure evolves from c-axis ferromagnetism at x = 0 to a canted antiferromagnetic (AFM) structure with reduced c-axis moment and in-plane AFM order at x = 0.12 and further reduced c-axis FM moment at x = 0.3. Since noncollinear spins can induce non-zero Berry curvature in real space acting as a fictitious magnetic field, our results revealed another AHE contribution, establishing the impact of magnetism on transport.

Canted antiferromagnetic order in EuZn2As2 single crystals

Compounds containing Eu show a vast range of unique physical properties due to the interplay of electronic and magnetic properties, which can lead to a nontrivial electronic topology combined with magnetic order. We report on the growth of trigonal (Poverline{3 }m1 space group) EuZn2As2 single crystals and on the studies of their structural, electronic and magnetic properties. A range of experimental techniques was applied including X-ray diffraction, electron microscopy, magnetic susceptibility, magnetization, heat capacity and Mössbauer spectroscopy in the study. We found that Eu has solely a 2+ valence state and its magnetic moments below TN = 19.2 K form a canted antiferromagnetic structure, tilted from the basal plane.

Synthesis and structural link to the electronic and magneto-transport properties of spin–orbit Mott insulator Sr2IrO4

We investigate the effect of sample preparation conditions on the link between the structural and physical properties of polycrystalline spin—orbit Mott insulator, Sr2IrO4. The samples were prepared in two batches. With the first batch prepared as per the commonly adopted procedure in literature and the second batch prepared adopting the same procedure as the first batch but with an additional annealing in vacuum. Interestingly, our results show that without change in the value of the Curie temperature (T C ), there occurs increase in the value of magnetization, resistivity, magneto-resistance (MR) and an increase in temperature range of stabilization of the canted antiferromagnetic structure. The temperature behaviour of the difference in the irreversible magnetization between the samples is in line with the difference in the Ir–O–Ir in-plane bond angle. At low temperatures, the conduction mechanism in the first batch of the sample is mainly governed by disorder while in the case of the other sample it is of Arrhenius type. The magneto-transport results have shown its strong link with the disorder and structural results. Although the nature and mechanism of the disorder needs to be investigated further, the present results throw light on the role of disorder and its connectivity between the structure and physical properties to understand its complex behaviours.

Effects of Bi doping on structural and magnetic properties of cobalt ferrite perovskite oxide LaCo0.5Fe0.5O3

Literature reports on magnetic transition of LaFe0.5Co0.5O3 are highly ambiguous. The present study is an endeavour to address that particular issue of this ferrite perovskite. Here we report the low temperature sol-gel synthesis of pure and Bi-doped La1-xBixFe0.5Co0.5O3 (x = 0, 0.1 & 0.2) perovskites. All the samples were characterized by powder X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray (EDX) analysis and magnetization studies. LaFe0.5Co0.5O3 crystallizes in a single phase rhombohedral (R-3c) structure. Substitution of Bi at the A-site results in structural transition. La0.9Bi0.1Fe0.5Co0.5O3 exhibits mixed rhombohedra (R-3c) and orthorhombic (Pbnm) phases, whereas La0.8Bi0.2Fe0.5Co0.5O3 is single phase orthorhombic (Pbnm). Favourable grain growth and good crystallinity observed in Bi doped samples are possibly due to the low melting temperature of Bi containing La1-xBixFe0.5Co0.5O3. EDX analysis confirms the chemical homogeneity of the samples. XPS studies and bond valence sum calculations confirm the nominal cationic oxidation states of the ions. Magnetization measurements reveal the weak ferromagnetic nature of La1-xBixFe0.5Co0.5O3 (x = 0, 0.1 & 0.2) which is associated to the canted antiferromagnetic structure. The magnetically active subsystem of Fe3+ ions are responsible for weak ferromagnetism which is explained by the antisymmetric Dzyaloshinskii–Moriya interaction, whereas the Co3+ ions remain predominantly in the low spin state. The increase in magnetic transition and the lower magnetic moment with an increase in Bi content can be related to the weakening of Dzyaloshinskii–Moriya interaction due to structural modification and local lattice distortion associated to the stereochemically active 6s2 lone pair electrons of the Bi3+ ions. Our results confirm the high structure sensitivity of magnetic properties of cobalt ferrite perovskite.

Unconventional Anomalous Hall Effect in the Canted Antiferromagnetic Half‐Heusler Compound DyPtBi

AbstractThe interplay between magnetism and the topological band in metamagnetic materials has attracted researchers’ attentions because these materials exhibit novel phenomena, such as the anomalous Hall effect (AHE) and quantum AHE. Here, the magnetotransport of DyPtBi single crystals in out‐of‐plane and in‐of‐plane magnetic field configurations is investigated. The results show a large unconventional anomalous Hall signal in the canted Type II antiferromagnetic state, indicating the existence of significant Berry curvature. This signal evolves into a large hump with DyPtBi entering the paramagnetic state and persists up to temperatures that are much higher than TN. Out‐of‐plane and in‐of‐plane measurements indicate that a larger unconventional Hall signal is observed at certain θ and ϕ angles. A giant planar anomalous Hall angle (AHA) of up to 30% is achieved in DyPtBi, which is comparable to that in a typical ferromagnetic Weyl semimetal. The results show that DyPtBi is a good platform for investigating the unconventional AHE and other novel physical properties in various potentially topologically nontrivial phases due to the interplay between canted antiferromagnetic structures and topology.

Magnetism in quasi-two-dimensional tri-layer La2.1Sr1.9Mn3O10 manganite

The tri-layer La_{3-3x}Sr_{1+3x}Mn_{3}O_{10} manganites of Ruddlesden–Popper (RP) series are naturally arranged layered structure with alternate stacking of ω-MnO_2 (ω = 3) planes and rock-salt type block layers (La, Sr)_2O_2 along c-axis. The dimensionality of the RP series manganites depends on the number of perovskite layers and significantly affects the magnetic and transport properties of the system. Generally, when a ferromagnetic material undergoes a magnetic phase transition from ferromagnetic to paramagnetic state, the magnetic moment of the system becomes zero above the transition temperature (T _{C} ). However, the tri-layer La_{2.1}Sr_{1.9}Mn_{3}O_{10} shows non-zero magnetic moment above T _{C} and also another transition at higher temperature T ^{*} approx 263 K. The non-zero magnetization above T _{C} emphasizes that the phase transition in tri-layer La_{2.1}Sr_{1.9}Mn_{3}O_{10} not a ferromagnetic to paramagnetic state. We show here the non-zero magnetic moment above T _{C} is due to the quasi-two-dimensional nature of the tri-layer La_{2.1}Sr_{1.9}Mn_{3}O_{10} manganite. The scaling of the magnetic entropy change confirms the second-order phase transition and the critical behavior of phase transition has been studied around T_C to understand the low dimensional magnetism in tri-layer La_{2.1}Sr_{1.9}Mn_{3}O_{10}. We have obtained the critical exponents for tri-layer La_{2.1}Sr_{1.9}Mn_{3}O_{10}, which belong to the short-range two-dimensional (2D)-Ising universality class. The low dimensional magnetism in tri-layer La_{2.1}Sr_{1.9}Mn_{3}O_{10} manganite is also explained with the help of renormalization group theoretical approach for short-range 2D-Ising systems. It has been shown that the layered structure of tri-layer La_{2.1}Sr_{1.9}Mn_{3}O_{10} results in three different types of interactions intra-planer ( J_{ab} ), intra-tri-layer ( J_{c} ) and inter-tri-layer ( J' ) such that J_{ab}> J_{c}>> J' and competition among these give rise to the canted antiferromagnetic spin structure above T _{C} . Based on the similar magnetic interaction in bi-layer manganite, we propose that the tri-layer La_{2.1}Sr_{1.9}Mn_{3}O_{10} should be able to host the skyrmion below T _{C} due to its strong anisotropy and layered structure.

First detection of low field microwave absorption in the disordered multiferroic double perovskite BiFe0.5Mn0.5O3

BiFe0.5Mn0.5O3 (BFMO) is an intriguing magnetic double perovskite, only obtainable through high pressure-high temperature synthesis. It shows bulk multiferroic properties, namely the coexistence between a spin canted antiferromagnetic structure superimposed to an externally induced electric polarization at least from 77 K. In particular, the system is characterized by a significant weak ferromagnetic hysteresis loop and by a very rare phenomenon: the spontaneous magnetization reversal (MRV) versus temperature in the low field regime. To clarify the BFMO exotic magnetic phase in the low field regime, the Electron Spin Resonance (ESR) and the low field microwave absorption (LFMA) techniques were used, providing the first observation of LFMA in the bulk BFMO as an additional functionality of this material. A striking feature is that the hysteresis in LFMA signals vanishes above 45 K, while the bulk M-H loop hysteresis, measured in the same field range of LFMA, persists till room temperature. The temperature at which LFMA hysteresis vanishes qualitatively matches the position of the magnetic susceptibility’s second derivative peak, corresponding to the temperature at which the local second order mechanism responsible for MRV is maximum. The line shape of LFMA completely changes above 45 K and the ESR linewidth starts decreasing above this temperature, indicating the role of defect/disorder induced inhomogeneity. The temperature evolution of LFMA hysteresis and line shapes as a measure of the competition between Fe- and Mn-rich clusters suggests a sort of local frustration at the microscopic scale, responsible for the peculiar magnetization reversal of this system.

Canted antiferromagnetic order and spin dynamics in the honeycomb-lattice compound Tb2Ir3Ga9

Single crystal neutron diffraction, inelastic neutron scattering, bulk magnetization measurements, and first-principles calculations are used to investigate the magnetic properties of the honeycomb lattice $\rm Tb_2Ir_3Ga_9$. While the $R\ln2$ magnetic contribution to the low-temperature entropy indicates a $\rm J_{eff}=1/2$ moment for the lowest-energy crystal-field doublet, the Tb$^{3+}$ ions form a canted antiferromagnetic structure below 12.5 K. Due to the Dzyalloshinskii-Moriya interactions, the Tb moments in the $ab$ plane are slightly canted towards $b$ by $6^\circ$ with a canted moment of 1.22 $\mu_{\rm B} $ per formula unit. A minimal $xxz$ spin Hamiltonian is used to simultaneously fit the spin-wave frequencies along the high symmetry directions and the field dependence of the magnetization along the three crystallographic axes. Long-range magnetic interactions for both in-plane and out-of-plane couplings up to the second nearest neighbors are needed to account for the observed static and dynamic properties. The $z$ component of the exchange interactions between Tb moments are larger than the $x$ and $y$ components. This compound also exhibits bond-dependent exchange with negligible nearest exchange coupling between moments parallel and perpendicular to the 4$f$ orbitals. Despite the $J_{{\rm eff}}=1/2$ moments, the spin Hamiltonian is denominated by a large in-plane anisotropy $K_z \sim -1$ meV. DFT calculations confirm the antiferromagnetic ground state and the substantial inter-plane coupling at larger Tb-Tb distances.

Сanted Magnetic Interlayer Ordering in a [Fe(3.0 nm)/Cr(1.2 nm)]10 Structure Revealed by Synchrotron Mössbauer Reflectometry with Polarization Analysis

Mossbauer reflectivity spectra measured for the [Fe(3.0 nm)/Cr(1.2 nm)]10 structure in the half-order Bragg peak, which corresponds to the doubling of the period, have revealed the formation of a canted antiferromagnetic structure under the action of an external magnetic field of $${{B}^{{{\text{ext}}}}} = 0.06$$ Т applied perpendicular to the scattering plane. This result certainly follows from the appearance of the second and fifth lines in the Mossbauer sextet, which should be suppressed for any symmetric orientation of the magnetic hyperfine field in two 57Fe layers in one magnetic period. The experiment involves a polarization analysis of the reflected beam and shows that this new approach simplifies the form of angular dependences and reflectivity spectra, since it eliminates the interfering contribution of nonresonant scattering, and improves the reliability of the data interpretation.

Evolution of the structural, magnetic, and electronic properties of the triple perovskite Ba3CoIr2O9

We report a comprehensive investigation of the triple perovskite iridate Ba$_{3}$CoIr$_{2}$O$_{9}$. Stabilizing in the hexagonal $P6_{3}/mmc$ symmetry at room temperature, this system transforms to a monoclinic $C2/c$ symmetry at the magnetic phase transition. On further reduction in temperature, the system partially distorts to an even lower symmetry ($P2/c$), with both these structurally disparate phases coexisting down to the lowest measured temperatures. The magnetic structure as determined from neutron diffraction data indicates a weakly canted antiferromagnetic structure, which is also supported by first-principles calculations. Theory indicates that the Ir$^{5+}$ carries a finite magnetic moment, which is also consistent with the neutron data. This suggests that the putative $J=0$ state is avoided. Measurements of heat capacity, electrical resistance noise and dielectric susceptibility all point towards the stabilization of a highly correlated ground state in the Ba$_{3}$CoIr$_{2}$O$_{9}$ system.

Noncollinear antiferromagnetic order in the buckled honeycomb lattice of magnetoelectric Co4Ta2O9 determined by single-crystal neutron diffraction

Co4Ta2O9 exhibits a three-dimensional magnetic lattice based on the buckled honeycomb motif. It shows unusual magnetoelectric effects, including the sign change and non-linearity. These effects cannot be understood without the detailed knowledge of the magnetic structure. Herein, we report neutron diffraction and direction-dependent magnetic susceptibility measurements on Co4Ta2O9 single crystals. Below 20.3 K, we find a long-range antiferromagnetic order in the alternating buckled and flat honeycomb layers of Co2+ ions stacked along the c axis. Within experimental accuracy, the magnetic moments lie in the ab plane. They form a canted antiferromagnetic structure with a tilt angle of ~ 14 degrees at 15 K in the buckled layers, while the magnetic moments in each flat layer are collinear. This is directly evidenced by a finite (0, 0, 3) magnetic Bragg peak intensity, which would be absent in the collinear magnetic order. The magnetic space group is C2'/c. It is different from the previously reported C2/c' group, also found in the isostructural Co4Nb2O9. The revised magnetic structure successfully explains the major features of the magnetoelectric tensor of Co4Ta2O9 within the framework of the spin-flop model.

Room temperature anomalous Hall effect in antiferromagnetic Mn3SnN films

Rich magnetic phase transition makes the antiperovskite manganese nitride Mn3AN family an ideal platform to explore the anomalous Hall effect (AHE) with different magnetic configurations. Here, we report the observation of AHE signals up to room temperature in antiferromagnetic (AFM) (001)-oriented Mn3SnN thin films. AHE signals, originated from the Berry curvature, can be controlled by the growth-induced biaxial strain, which leads to the modulation of noncollinear AFM configurations. A relatively large biaxial strain could enhance AHE signals ascribed to the canted AFM structure induced by the piezomagnetic effect. Our findings advance the effective utilization of the AHE in AFM spintronics.

Canted antiferromagnetism in the quasi-one-dimensional iron chalcogenide BaFe2Se4

We report the synthesis and physical properties studies of quais-1D iron chalcogenide $\rm BaFe_2Se_4$ which shares the $\rm FeSe_4$ tetrahedra building motif commonly seen in the iron chalcogenide superconductors. A high-quality polycrystalline sample was achieved by solid-state reaction method and characterized by X-ray diffraction, electrical resistivity, magnetic susceptibility and neutron diffraction measurements. $\rm BaFe_2Se_4$ is a narrow gap semiconductor that magnetically orders at $\sim$ 310 K. Both neutron powder diffraction results and isothermal M-H loops suggest a canted antiferromagnetic structure where Fe sublattice are antiferromagnetically ordered along the c-axis quasi-1D chain direction, resulting in a net ferromagnetic moment in the perpendicular direction along the a-axis with tilted angle of 18.7$^\circ$ towards the b-axis.

Unconventional magnetic ferroelectricity in the quadruple perovskite NaMn7O12

By means of magnetic, specific heat and pyroelectric measurements, we report on magnetic ferroelectricity in the quadruple perovskite \namno, characterized by a canted antiferromagnetic (AFM) CE structure. Surprisingly, ferroelectricity is concomitant to a dramatic broadening of the magnetic hysteresis loop, well below the AFM ordering temperature. This unconventional behavior shows that the formation of ferroelectric domains is induced by the symmetric exchange interaction in the local scale, e.g. at magnetic domain boundaries or defects. The value of electric polarization, $P = 0.027 \mu$C cm$^{-2}$, measured in polycrystalline samples is comparatively large as compared to other magnetic multiferroics, suggesting that the above scenario is promising indeed for the rational design of practical multiferroic materials.

Enhanced magnetocaloric effect and magnetic phase diagrams of single-crystal GdCrO3

The crystalline structure, magnetism, and magnetocaloric effect of a GdCrO$_3$ single crystal grown with the laser-diode-heated floating-zone technique have been studied. The GdCrO$_3$ single crystal crystallizes into an orthorhombic structure with the space group $Pmnb$ at room temperature. Upon cooling, under a magnetic field of 0.1 T, it undergoes a magnetic phase transition at $T_{\textrm{N-Cr}} =$ 169.28(2) K with Cr$^{3+}$ ions forming a canted antiferromagnetic (AFM) structure, accompanied by a weak ferromagnetism. Subsequently, a spin reorientation takes place at $T_{\textrm{SR}} =$ 5.18(2) K due to Gd$^{3+}$-Cr$^{3+}$ magnetic couplings. Finally, the long-range AFM order of Gd$^{3+}$ ions establishes at $T_{\textrm{N-Gd}} =$ 2.10(2) K. Taking into account the temperature-(in)dependent components of Cr$^{3+}$ moments, we obtained an ideal model for describing the paramagnetic behavior of Gd$^{3+}$ ions within 30--140 K. We observed a magnetic reversal (positive $\rightarrow$ negative $\rightarrow$ positive) at 50 Oe with a minimum centering around 162 K. In the studied temperature range of 1.8-300 K, there exists a strong competition between magnetic susceptibilities of Gd$^{3+}$ and Cr$^{3+}$ ions, leading to puzzling magnetic phenomena. We have built the magnetic-field-dependent phase diagrams of $T_{\textrm{N-Gd}}$, $T_{\textrm{SR}}$, and $T_{\textrm{N-Cr}}$, shedding light on the nature of the intriguing magnetism. Moreover, we calculated the magnetic entropy change and obtained a maximum value at 6 K and ${\Delta}{\mu}_0H$ = 14 T, i.e., -${\Delta}S_{\textrm{M}} \approx$ 57.5 J/kg K. Among all RCrO$_3$ (R = $4f^n$ rare earths, $n =$ 7-14) compounds, the single-crystal GdCrO$_3$ compound exhibits the highest magnetic entropy change, as well as an enhanced adiabatic temperature, creating a prominent magnetocaloric effect for potential application in magnetic refrigeration.

Crystalline and magnetic structures, magnetization, heat capacity, and anisotropic magnetostriction effect in a yttrium-chromium oxide

We have studied a nearly stoichiometric insulating Y$_{0.97(2)}$Cr$_{0.98(2)}$O$_{3.00(2)}$ single crystal by performing measurements of magnetization, heat capacity, and neutron diffraction. Albeit that the YCrO$_3$ compound behaviors like a soft ferromagnet with a coersive force of $\sim$ 0.05 T, there exist strong antiferromagnetic (AFM) interactions between Cr$^{3+}$ spins due to a strongly negative paramagnetic Curie-Weiss temperature, i.e., -433.2(6) K. The coexistence of ferromagnetism and antiferromagnetism may indicate a canted AFM structure. The AFM phase transition occurs at $T_\textrm{N} =$ 141.5(1) K, which increases to $T_\textrm{N}$(5T) = 144.5(1) K at 5 T. Within the accuracy of the present neuron-diffraction studies, we determine a G-type AFM structure with a propagation vector \textbf{k} = (1 1 0) and Cr$^{3+}$ spin directions along the crystallographic \emph{c} axis of the orthorhombic structure with space group \emph{Pnma} below $T_\textrm{N}$. At 12 K, the refined moment size is 2.45(6) $\mu_\textrm{B}$, $\sim$ 82\% of the theoretical saturation value 3 $\mu_\textrm{B}$. The Cr$^{3+}$ spin interactions are probably two-dimensional Ising like within the reciprocal (1 1 0) scattering plane. Below $T_\textrm{N}$, the lattice configuration (\emph{a}, \emph{b}, \emph{c}, and \emph{V}) deviates largely downward from the Gr$\ddot{\textrm{u}}$neisen law, displaying an anisotropic magnetostriction effect and a magnetoelastic effect. Especially, the sample contraction upon cooling is enhanced below the AFM transition temperature. There is evidence to suggest that the actual crystalline symmetry of YCrO$_3$ compound is probably lower than the currently assumed one. Additionally, we compared the $t_{2\textrm{g}}$ YCrO$_3$ and the $e_\textrm{g}$ La$_{7/8}$Sr$_{1/8}$MnO$_3$ single crystals for a further understanding of the reason for the possible symmetry lowering.

Magnetization spin reversal and neutron diffraction study of polycrystalline Tb0.55Sr0.45MnO3

We have investigated the structural and magnetic phase transitions in Sr doped polycrystalline Tb0.55Sr0.45MnO3, using temperature-dependent high-resolution neutron powder diffraction in the HRPT diffractometer at PSI to address the origin of magnetization reversal at low temperature. The solid solution Tb0.55Sr0.45MnO3 crystallizes in O′ type orthorhombic structure having the Pnma symmetry. The substitution of the divalent cation of Sr2+ at the site of Tb3+ dilutes the Mn–Tb interaction and affects the magnetic structure, which was observed by the field and temperature-dependent dc magnetization and neutron diffraction study. The temperature-dependent zero field-cooled and field cooled dc magnetization study reveals the indication of spin reversal phenomena, which is the nature of canted antiferromagnetic or ferrimagnetic transition at 100 Oe because of Mn–Mn sub-lattices interaction below 65 K. By increasing the applied magnetic field up to 20 kOe, a weak ferromagnetic type of behaviour is observed. The field-dependent magnetization shows weak coercivity due to the canted spin structure at low temperatures. The low-temperature neutron diffraction study of polycrystalline Tb0.55Sr0.45MnO3 reveals the non-collinear canted antiferromagnetic structure due to Tb ordering at 1.5 K, which turns into a non-collinear ferromagnetic structure along with spin canting followed by the spin reversal phenomena at 25 K.