Antiparallel Spin Alignment Research Articles

Suppressing energy migration via antiparallel spin alignment in one‐dimensional Mn2+ halide magnets with high luminescence efficiency

Photoexcited energy migration is prone to causing luminescence quenching in Mn2+ luminescent materials, presenting a formidable challenge for optoelectronic applications. Although various strategies and mechanisms have been proposed to mitigate this issue, the role of spin alignment between adjacent Mn2+ ions has remained largely unexamined. In this study, we have elucidated the influence of spin alignment on energy migration within the one‐dimensional Mn2+‐metal halide compound (CH3)4NMnCl3 (TMMC) through variable‐temperature photoluminescence (PL) and magnetic‐optical spectroscopy. This investigation was conducted with reference to (CH6N3)2MnCl4 (GUA) with isolated [Mn3Cl12]6‐ trimers and Cd2+‐doped TMMC. The spin order in TMMC below approximately 55 K is demonstrated by the disorder‐order transition observed in the temperature‐dependent magnetic susceptibility. This finding is further corroborated by the negligible shift in the temperature‐ and field‐dependent emission peaks, a consequence of magnetic saturation. Our results indicate that the antiparallel spin alignment along the Mn2+ chain in TMMC effectively suppresses energy migration and multiphonon relaxation, thereby reducing nonradiative transitions and enhancing the photoluminescence quantum yield (PLQY).This research casts new light on the potential for developing high‐performance Mn2+‐doped phosphors for optoelectronic and spin‐photonic applications, offering insights into the manipulation of spin and energy dynamics in these materials.

Suppressing energy migration via antiparallel spin alignment in one-dimensional Mn2+ halide magnets with high luminescence efficiency.

Photoexcited energy migration is prone to causing luminescence quenching in Mn2+ luminescent materials, presenting a formidable challenge for optoelectronic applications. Although various strategies and mechanisms have been proposed to mitigate this issue, the role of spin alignment between adjacent Mn2+ ions has remained largely unexamined. In this study, we have elucidated the influence of spin alignment on energy migration within the one-dimensional Mn2+-metal halide compound (CH3)4NMnCl3 (TMMC) through variable-temperature photoluminescence (PL) and magnetic-optical spectroscopy. This investigation was conducted with reference to (CH6N3)2MnCl4 (GUA) with isolated [Mn3Cl12]6- trimers and Cd2+-doped TMMC. The spin order in TMMC below approximately 55 K is demonstrated by the disorder-order transition observed in the temperature-dependent magnetic susceptibility. This finding is further corroborated by the negligible shift in the temperature- and field-dependent emission peaks, a consequence of magnetic saturation. Our results indicate that the antiparallel spin alignment along the Mn2+ chain in TMMC effectively suppresses energy migration and multiphonon relaxation, thereby reducing nonradiative transitions and enhancing the photoluminescence quantum yield (PLQY).This research casts new light on the potential for developing high-performance Mn2+-doped phosphors for optoelectronic and spin-photonic applications, offering insights into the manipulation of spin and energy dynamics in these materials.

A systematic investigation of chromium and vanadium impurities in a Janus Ga2SO monolayer towards spintronic applications.

Transition metals (TMs) have been employed as efficient sources of magnetism in non-magnetic two-dimensional (2D) materials. In this work, doping with chromium (Cr) and vanadium (V) is proposed to induce feature-rich electronic and magnetic properties in a Janus Ga2SO monolayer towards spintronic applications. The Ga2SO monolayer is a 2D semiconductor material with an energy gap of 1.30 (2.12) eV obtained from PBE(HSE06)-based calculations. Considering the structural asymmetry, different vacancy and doping sites are considered. A single Ga vacancy and pair of Ga vacancies magnetize the monolayer with total magnetic moments between 0.69 and 3.13μB, where the half-metallic nature is induced by the single Ga1 vacancy (that bound to the S atom). In these cases, the magnetism is originated mainly from S and O atoms closest to the vacancy sites. Depending on the doping site, either half-metallicity or diluted magnetic semiconductor natures are obtained by doping with Cr and V atoms with total magnetic moments of 3.00 and 2.00μB, respectively. Herein, 3d TM impurities produce mainly the system magnetism. When substituting a pair of Ga atoms, TM atoms exhibit the antiparallel spin alignment to follow the Pauli exclusion principle, retaining the novel electronic characteristics induced by a single TM dopant. Except for the case of doping with a pair of V atoms, total magnetic moments of 2.00 and 1.00μB are obtained by doping with a pair or Cr atoms and Cr/V co-doping, respectively. The non-zero magnetic moment is derived from the different interactions of each TM atom with its neighboring atoms, which will also be studied by Bader charge analysis. Our results introduce new promising 2D spintronic candidates, which are made by structural modifications at Ga sites of a non-magnetic Janus Ga2SO monolayer.

Magnetic and magneto-optical properties of manganese-containing antimony phosphate glasses – An alternative to Faraday rotators

Glasses in system 100-x(70SbPO4–10ZnO–20PbO) xMnO, with x = 0, 10, 20 and 30 mol %, where prepared by the conventional melting-quenching method. The glasses were cut, polished and characterized by XRD, DSC, Raman, FTIR, UV–Vis and luminescence and magnetic and magneto-optical aiming application ultimate as in magneto-optical devices. These samples containing manganese exhibit magnetic response to neodymium magnets at room temperature. In addition, they feature thermal stability above 100 °C, wide transparency in the visible and near infrared region. The optical absorption spectra of the glass revealed the presence of characteristic absorption bands of Mn2+ at 410 nm attributed to 6A1(S) → 4A1, 4E (4G) transition and possible oxidation at around 550 nm assigned to 5B1g → 5B2g transition of the Mn3+ ions. Refractive indices higher than 1.8 and characteristic emission bands around 680–720 nm, assigned to 4T1(G)→6A1(S) transition, were also observed. Magnetic susceptibility measurements revealed the paramagnetic character of the Mn-containing glasses, with antiparallel spin alignment. Finally, a linear growth trend was observed for the Verdet constant along with the Mn2+ concentration and the highest value measured, for sample containing 30 mol% of MnO, was −55.1 ± 3.2 rad T−1 m−1 at 632.8 nm. This value is close to those of some families of glasses containing rare earths, being an alternative of new low-cost magneto-optical vitreous materials.

Interplay of Magnetic Interaction and Electronic Structure in New Structure RE-12442 Type Hybrid Fe-Based Superconductors

We present detailed first-principles density functional theory-based studies on RbRE2Fe4As4O2 (RE = Sm, Tb, Dy, Ho) hybrid 12442-type iron-based superconducting compounds with particular emphasis on competing magnetic interactions and their effect on possible magneto-structural coupling and electronic structure. The stripe antiferromagnetic (sAFM) pattern across the xy plane emerges as the most favorable spin configuration for all the four compounds, with close competition among the different magnetic orders along the z-axis. The structural parameters, including arsenic heights, Fe-As-Fe angle, and other relevant factors that influence superconducting Tc and properties, closely match the experimental values in stripe antiferromagnetic arrangement of Fe spins. Geometry optimization with inclusion of explicit magnetic ordering predicts a spin–lattice coupling for all the four compounds, where a weak magneto–structural transition, a tetragonal-to-orthorhombic structural transition, takes place in the relaxed stripe antiferromagnetic spin configuration. Absence of any experimental evidence of such structural transition is possibly an indication of nematic transition in RE-12442 compounds. As a result of structural distortion, the lattice contracts (expands) along the direction with parallel (anti-parallel) alignment of Fe spins. Introduction of stripe antiferromagnetic order in Fe sub-lattice reconstructs the low-energy band structure, which results in significantly reduced number of bands crossing the Fermi level. Moreover, the dispersion of bands and their orbital characteristics also are severely modified in the stripe antiferromagnetic phase similar to BaFe2As2. Calculations of exchange parameters were performed for all the four compounds. Exchange coupling along the anti-parallel alignment of Fe spins J1a is larger than that for the parallel aligned spins J1b. A crossover between the super-exchange-driven in-plane next-nearest-neighbor exchange coupling J2 and in-plane exchange coupling J1a due to lanthanide substitution was found. A large super-exchange-driven next-nearest-neighbor exchange interaction is justified using the construction of 32 maximally localized Wannier functions, where the nearest-neighbor Fe-As hopping amplitudes were found to be larger than the nearest- and the next-nearest-neighbor Fe-Fe hopping amplitudes. We compare the hopping parameters in the stripe antiferromagnetic pattern with non-magnetic configuration, and increased hopping amplitude was found along the anti-parallel spin alignment with more majority-spin electrons in Fe dxz and dxy but not in Fe dyz. On the other hand, the hopping amplitudes are increased in stripe antiferromagnetic phase along the parallel spin alignment with more majority-spin electrons in only Fe dyz. This difference in hopping amplitudes in the stripe antiferromagnetic order enables more isotropic hopping.

Achieving High-Temperature Multiferroism by Atomic Architecture

Materials with multiple order parameters, typically, in which ferroelectricity and magnetism are coupled, are illuminative for next-generation multifunctional electronics. However, searching for such single-phase multiferroics is challenging owing to antagonistic orbital occupancy and chemical bonding requirements for polarity and magnetism. Appropriate multiferroic candidates have been proposed, but their practical implementation is impeded by the low working temperature, weak coupling between ferroic orders, or antiparallel spin alignment in magnetic sublattices. Here, we report a family of single-phase multiferroic materials in which high-temperature magnetism and voltage-switchable ferroelectricity are coupled. Using pulsed laser deposition, we have fabricated single-crystalline thin films incorporating a uniformly percolated open-shell dn framework, which are composed of Fe cations with B-site occupancy and exhibit long-range spin ordering into the displacive ferroelectric PbTiO3 lattice, as demonstrated by atomically resolved chemical analysis. The tetragonal polar Pb(Ti1-x,Fex)O3 (PFT(x), x ≤ 0.10) family exhibits a switchable ferroelectric nature and magnetic interaction with a moderate coercive field of around 300 Oe at room temperature. Notably, the magnetic order even persists above 500 K, which is higher than already reported potential multiferroic candidates until now. Our strategy of merging a spin-ordered sublattice into inherent ferroelectrics via atomic occupancy engineering provides an available pathway for highly thermally stable multiferroic and spintronic applications.

Room temperature magnetoelectric coupling in Pb(Fe1/2Nb1/2)O3 by counterbalancing imbalanced spin moments through spin canting

In this study, ferroelectric Pb(Fe1/2Nb1/2)O3 with an antiferromagnetic polymorph at and below 150 K was converted into a room-temperature magnetoelectrically active multiferroic with soft ferromagnetism by disrupting the existing antiparallel spin alignment of Fe ions through the heavy replacement of Fe by Ni. To maximize the induced soft-ferromagnetic properties and the consequent nonlinear magnetoelectric coupling, the substitution level of Ni should be controlled such that the individual Ni ions are separated from one another to avoid mutual spin cancellation. The induced magnetoelectric coupling was found to originate from the collective contribution of oppositely canted pairs of spins in two nearby Fe3+ ions, which counterbalances the relatively smaller spin moment of the in-between Ni ions. The non-material specific nature of this strategy implies that it can be used in the development of new room-temperature multiferroic perovskite oxides.

The role of impurities and oxygen vacancies in the magnetic response of FexCoySn1-x-yO2. Experimental and ab initio study

In this work we present an experimental and theoretical study of the magnetic and hyperfine properties of (Fe, Co) co-doped rutile SnO2 (FexCoySn1-x-yO2). Ab initio calculations were performed in the framework of the Density Functional Theory (DFT) using the full-potential linearized augmented plane wave (FP-LAPW) method. The effect of the oxygen vacancies on the magnetic and hyperfine properties and on the magnetic alignment of Fe and Co impurities was studied considering different vacancy concentrations and distributions in the host. Our calculations predicted that the Fe and Co impurities tend to be located as close as possible and favors the generation of oxygen vacancies, forming a pair of magnetic impurities sharing oxygen vacancies with an antiparallel spin alignment, giving rise to a ferrimagnetic entity. Ab initio predictions were compared with experimental results: magnetization curves obtained by vibrating sample magnetometry (VSM) at room temperature and Mössbauer spectroscopy (MS) studies obtained for SnO2 samples doped with 1.0% of Fe and co-doped with Co concentrations ranging from 0.0 to 0.5%, grown by sol-gel and thermal decomposition method. The comparison enabled us to identify the observed hyperfine interactions in MS experiments and characterize the local structure around the Fe atoms unambiguously. Finally, based on our theoretical results for the lowest energy Fe–Fe, Fe–Co and Co–Co magnetic configurations we can understand and reproduce the experimental behavior obtained by VSM measurements of the saturation magnetization (MS) (similar to the magnetic moment per magnetic atom) as a function of the Co concentration.

Ab initio calculation of interlayer exchange coupling in Co-based synthetic antiferromagnet with alloy spacer

Synthetic antiferromagnets (SAF) are widely used in magnetic tunnel junctions in order to reduce the stray field of the pinned layer. In SAF, the antiparallel spin alignment is stabilized by interlayer exchange coupling (IEC) between two ferromagnetic layers that are separated by a spacer layer. The strength of IEC depends on the spacer material. It is known that strong IEC is required for stable operation of magnetic random access memory with a low error rate, and hence a spacer material that shows strong IEC has been highly sought after. In this study, we investigate the IEC of ordered alloy spacers in Co multilayers by ab initio calculations based on density functional theory. We find that the IEC of binary alloy spacers composed of group 8 and 9 elements, namely, RuIr, RuRh, and OsIr, are greater than that of Ru and Ir spacers, which have commonly been used in SAF pinned layers. We also present dependence of IEC strength on the composition ratio of these alloy spacers. The relation between the strength of IEC and the lattice length is discussed.

Magnetorefractive Effect for Co/Ru Multilayer Film with Antiferromagnetic Interlayer Exchange Coupling

SUMMARYThe spin‐dependent scattering of conduction electron in metallic magnetic multilayers was investigated to reveal the optical properties which corresponded to the magnetization state. From the measurement of magnetorefractive effect in antiferro‐magnetically exchange coupled Co/Ru multilayers, it was found that (1) the transmittance varied around 1% at wavelength of 1550 nm during the parallel/antiparallel spin alignment changes, (2) as a result of number of repetition and Co thickness for the multilayers, transmittance difference between the parallel and antiparallel spin alignment states had trade‐off relationship with the magnitude of transmittance, and (3) asymmetric Co/Ru/Co stacking structure brought different interlayer exchange coupling fields in each layer, which resulted in magnetic field sensitive transmittance.

Ab initio study of exchange coupling for the consistent understanding of the magnetic ordering at room temperature in V[TCNE] x

We report quantum chemical calculations providing the exchange coupling constants of the V[TCNE]2 model system, describing the amorphous room temperature molecular magnet V[TCNE] x (TCNE = tetracyanoethylene, x ~ 2). The geometry is optimized for the ideal lattice using density functional theory (DFT) calculations with periodic boundary conditions. Broken-symmetry DFT calculations indicate antiparallel spin alignment resulting in ferrimagnetic ordering, but heavily overestimate the value of the exchange coupling. Better estimates of the exchange coupling parameters between the V(II) ion and the [TCNE]− anionic radical are obtained by means of multiconfigurational calculations performed on smaller molecular models cut from the optimized crystal lattice. Complete active space self-consistent field and multireference second-order perturbation theory calculations provide the sign and the strength of the nearest-neighbor as well as next-nearest-neighbor interactions along all three crystallographic directions. We are able to explain also intuitively the mechanism for antiferromagnetic spin coupling in terms of the superexchange pathways, discussing the role of the main four types of contributions to superexchange. Moreover, we clarify the influence of the transition metal ion on the strength of the exchange interaction and on the critical temperature for long-range ferrimagnetic ordering.

Magnetic and magneto-optical quenching in (Mn^2+, Sr^2+) metaphosphate glasses

Transition metal ions such as Mn2+, Fe2+, or Co2+ provide an interesting alternative to rare earth dopants in optically active glasses. In terms of their magneto-optical properties, they are not yet very well exploited. Here, we report on the effect of Mn2+ on Faraday rotation in a metaphosphate glass matrix along the join MnxSr1-x(PO3)2 with x = 0...1. Mn2+ shows small optical extinction in the visible spectral range and, compared to other transition metal ions, a high effective magnetic moment. At high Mn- levels, however, the magneto-optical activity of Mn2+ is strongly quenched due to ionic clustering. The magnetic properties of the heavily Mn2+-loaded phosphate matrix are dominated by a superexchange interaction in the Mn2+-O-Mn2+ bridge with antiparallel spin alignment between Mn2+ and O2- species. The apparent paramagnetic potential of Mn2+ species can therefore not be exploited at room temperature.

Photo-Induced Spin Dynamics in Nanoelectronic Devices

The present research is devoted to the investigation of electron spin transmission through a nanoelectronic device. This device is modeled as nonmagnetic semiconductor quantum dot coupled to two diluted magnetic semiconductor leads. The spin transport characteristics through such a device are investigated under the effect of an ac-field of a wide range of frequencies. The present result shows a periodic oscillation of the conductance for both the cases of parallel and antiparallel spin alignment. These oscillations are due to Fano-resonance. Results for spin polarization and giant magneto-resistance show the coherency property. The present research might be useful for developing single spin-based quantum bits (qubits) required for quantum information processing and quantum spin-telecommunication.

Anion Dependent Redox Changes in Iron Bis-terdentate Nitroxide {NNO} Chelates

The reaction of [Fe(II)(BF(4))(2)]·6H(2)O with the nitroxide radical, 4,4-dimethyl-2,2-di(2-pyridyl) oxazolidine-N-oxide (L(•)), produces the mononuclear transition metal complex [Fe(II)(L(•))(2)](BF(4))(2) (1) which has been investigated using temperature dependent susceptibility, Mössbauer spectroscopy, electrochemistry, density functional theory (DFT) calculations, and X-ray structure analysis. Single crystal X-ray diffraction analysis and Mössbauer measurements reveal an octahedral low spin Fe(2+) environment where the pyridyl donors from L(•) coordinate equatorially while the oxygen containing the radical from L(•) coordinates axially forming a linear O(•)··Fe(II)··O(•) arrangement. Magnetic susceptibility measurements show a strong radical-radical intramolecular antiferromagnetic interaction mediated by the diamagnetic Fe(2+) center. This is supported by DFT calculations which show a mutual spatial overlap of 0.24 and a spin density population analysis which highlights the antiparallel spin alignment between the two ligands. Similarly the monocationic complex [Fe(III)(L(-))(2)](BPh(4))·0.5H(2)O (2) has been fully characterized with Fe-ligand and N-O bond length changes in the X-ray structure analysis, magnetic measurements revealing a Curie-like S = 1/2 ground state, electron paramagnetic resonance (EPR) spectra, DFT calculations, and electrochemistry measurements all consistent with assignment of Fe in the (III) state and both ligands in the L(-) form. 2 is formed by a rare, reductively induced oxidation of the Fe center, and all physical data are self-consistent. The electrochemical studies were undertaken for both 1 and 2, thus allowing common Fe-ligand redox intermediates to be identified and the results interpreted in terms of square reaction schemes.

Appearance of a Large Magnetization at Elevated Temperatures in Nearly Antiferromagnetic α-Fe2O3

A significant magnetization of about 10–20 emu/g has been observed under a magnetic field of 5 kOe in nearly antiferromagnetic α-Fe2O3 when heated at 350–500 °C in air. The present outstanding effect that contrasts with the temperature dependence of the Curie's law has been investigated on the basis of various temperature-dependent measurements of magnetization, diffuse reflectance spectra, electrical conductivity, Seebeck potential, X-ray and neutron diffractions, differential scanning calorimetry, thermogravimetry, and X-ray photoelectron spectra. The color of α-Fe2O3 is found to drastically change from vivid red to black at about 380 °C, and this is closely correlated with the appearance of the magnetization. The color change is due to the formation of oxygen defects called a color center (i.e., F-center). Then, the absence of the intervening O2- ions greatly disturbs the superexchange interaction that is responsible for the anti-parallel spin alignment in the Fe–O–Fe (cation–anion–cation) system. As a result, the uncoupled spins can be aligned in parallel due to the direct exchange interaction between various nearest-neighboring Fe3+ ions, resulting in the appearance of the large magnetization at elevated temperatures.

Orientational phase transitions of a lattice of magnetic dots embedded in a London-typesuperconductor

In recent experiments, structured arrays of ferromagnetic nanoparticles in the bulk ofa superconductor have been fabricated. We present the theory of orientationalphase transitions in a planar regular lattice of nanoscale ferromagnetic particlesembedded in a superconductor. In the London approximation, we show that theinteractions between ferromagnetic particles can lead to either a parallel or antiparallelspin alignment depending on the ratio of the interparticle distance, the Londonpenetration depth and the temperature. The extension of the results to systemsof ferromagnetic nanoparticles with more complicated geometries is discussed.

Weak antiferromagnetic coupling in molecular ring is predicted correctly by density functional theory plus Hubbard U

We apply density functional theory with empirical Hubbard U parameter (DFT+U) to study Mn-based molecular magnets. Unlike most previous DFT+U studies, we calibrate U parameters for both metal and ligand atoms using five binuclear manganese complexes as the benchmarks. We note delocalization of the spin density onto acetate ligands due to pi-back bonding, inverting spin polarization of the acetate oxygen atoms relative to that predicted from superexchange mechanism. This inversion may affect the performance of the models that assume strict localization of the spins on magnetic centers for the complexes with bridging acetate ligands. Next, we apply DFT+U methodology to Mn(12) molecular wheel and find antiparallel spin alignment for the weakly interacting fragments Mn(6), in agreement with experimental observations. Using the optimized geometry of the ground spin state instead of less accurate experimental geometry was found to be crucial for this good agreement. The protocol tested in this study can be applied for the rational design of single molecule magnets for molecular spintronics and quantum computing applications.

The plumbide CeZnPb – Structure, magnetism, and chemical bonding

The plumbide CeZnPb was synthesized from the elements in a sealed tantalum ampoule. Its YPtAs-type structure was refined on the basis of single-crystal X-ray diffraction data: P6 3/ mmc, a = 463.7(2) and c = 1669.6(6) pm, w R2 = 0.1161, 189 F 2 values, and 12 variables. CeZnPb crystallizes with a superstructure of AlB 2. The zinc and lead atoms form puckered [Zn 3Pb 3] hexagons, which are stacked in a sequence ABB′ A′. The Zn–Pb distances within the layers are 278 pm. The shortest interlayer distance occurs between the zinc atoms of adjacent layers (305 pm). Susceptibility measurements of CeZnPb show Curie–Weiss behavior with an experimental magnetic moment of 2.47(1) μ B/mol CeZnPb. CeZnPb shows two antiferromagnetic transitions at T N1 = 3.8 K and T N2 = 2.6 K. Magnetization measurements at 2 K show two metamagnetic transitions at critical fields of approximately 1.1 and 7.0 kOe, underlining the antiparallel spin alignment at zero field. The electronic and magnetic structure is discussed based on scalar relativistic computations using the augmented spherical wave (ASW) method within density functional theory (DFT). As a result, our calculations employing the generalized gradient approximation (GGA) reveal a delicate competition of ferro and antiferromagnetic interactions. Only after properly taking into account the electronic correlations present in CeZnPb via a GGA + U treatment we are able to correctly describe the antiferromagnetic ground state. In addition, our calculations give a clue to the metamagnetic transitions as being due to the inherent geometric frustration of the cerium spin system.

Magnetism of Zn 0.98Co 0.02O nanopowders

We prepared Zn 0.98Co 0.02O nanopowders by conventional sol–gel method. The powders were sintered at different temperatures. The X-ray diffraction patters showed only wurtzite structure without any impurity phase, better crystalline structure and larger grain size with higher sintering temperature. The magnetic measurements showed that all the powders exhibited paramagnetism with weak antiferromagnetic exchange interaction. The quenched magnetic moment of Co ions was attributed to the weak antiferromagnetic exchange interaction between single Co ions and the antiparallel spin alignment of neighboring aggregated Co ions.

Crystal structure, phase transition, and magnetic ordering in perovskitelikePb2−xBaxFe2O5solid solutions

The crystal and magnetic structures of the $x\ensuremath{\approx}1$ member of the ${\text{Pb}}_{2\ensuremath{-}x}{\text{Ba}}_{x}{\text{Fe}}_{2}{\text{O}}_{5}$ solid solution series have been studied using x-ray and neutron powder diffraction, electron diffraction, high-resolution electron microscopy, and M\"ossbauer spectroscopy. ${\text{Pb}}_{1.08}{\text{Ba}}_{0.92}{\text{Fe}}_{2}{\text{O}}_{5}$ has two polymorphic forms with the orthorhombic unit cell with $a\ensuremath{\approx}\ensuremath{\surd}2{a}_{p}$, $b\ensuremath{\approx}{a}_{p}$, and $c\ensuremath{\approx}4\ensuremath{\surd}2{a}_{p}$ (${a}_{p}$---the parameter of the perovskite subcell) with the $Pnma$ space group of the low-temperature (LT) phase and the $Imma$ space group of the high-temperature (HT) phase, which are related by a phase transition at ${T}_{c}\ensuremath{\approx}540\text{ }\text{K}$. The crystal structures of both polymorphs were refined from neutron powder-diffraction data at $T=14\text{ }\text{K}$ and $T=700\text{ }\text{K}$. The structure consists of parallel perovskite blocks with the thickness of two ${\text{FeO}}_{6}$ octahedra linked together by infinite chains of edge-sharing distorted ${\text{FeO}}_{5}$ trigonal bipyramids with two columns of the Pb cations in between characterized by the asymmetric coordination environment due to localized $6{s}^{2}$ lone electron pair. Two mirror-related configurations of the trigonal bipyramidal chains are ordered in the LT structure; their arrangement becomes disordered in the HT structure. Below ${T}_{N}=625\text{ }\text{K}$, ${\text{Pb}}_{1.08}{\text{Ba}}_{0.92}{\text{Fe}}_{2}{\text{O}}_{5}$ transforms into an antiferromagnetically ordered state. The antiferromagnetic (AFM) structure with a propagation vector $\mathbf{k}=[0,\frac{1}{2},\frac{1}{2}]$ is characterized by an antiparallel spin alignment for all nearest-neighbor Fe atoms in the perovskite blocks, which stack on to each other at the trigonal bipyramidal chains, resulting in alternating antiparallel and parallel arrangement of spins on going along the common edge of the ${\text{FeO}}_{5}$ trigonal bipyramids. An unusual spin flipping dynamic behavior was revealed by M\"ossbauer spectroscopy and related to a specific character of superexchange interactions inside the chains of the ${\text{FeO}}_{5}$ trigonal bipyramids.