Diamagnetic Dilution Research Articles

Aggregation‐induced suppression of quantum tunneling by manipulating intermolecular arrangements of magnetic dipoles

AbstractThe relaxation time under zero field reflects the memory retention capabilities of single‐molecule magnets (SMMs) when used as storage devices. Intermolecular magnetic dipole interaction is ubiquitous in aggregates of magnetic molecules and can greatly influence relaxation times. However, such interaction is often considered harmful and challenging to manipulate in molecular solids, especially for high‐performance lanthanide single‐ion magnets (SIMs). By an elaborately designed combination of ion pairing and hydrogen bonding, we have synthesized two pseudo‐D5h SIMs with supramolecular arrangements of magnetic dipoles in staggered and side‐by‐side patterns, the latter of which exhibits a 104‐fold slower zero‐field relaxation time at 2 K. Intriguingly, the side‐by‐side complex exhibits a significantly accelerated magnetic relaxation upon diamagnetic dilution, contrary to the general trend observed in the staggered complex. This strongly reveals the presence of aggregation‐induced suppression of quantum tunneling in a side‐by‐side arrangement, which has not been observed in mononuclear SMMs. By leveraging ion‐pairing aggregation and converting to a side‐by‐side pattern, this study successfully demonstrates an approach to transform a harmful intermolecular dipole interaction into a beneficial one, achieving a τQTM of 980 s ranking among the best‐performance SMMs.

Slow magnetic relaxation behaviors and diamagnetic dilution studies of a carboxyl bridged dinuclear dysprosium(III) complex

By using a rigid bulky carboxylic ligand α-cyanocinnamic acid (CCA), a dinuclear dysprosium (III) complex [Dy2(CCA)6 (MeOH)4] (1) was synthesized. Single crystal X-ray crystallography reveals that the two eight-coordinate dysprosium ions are bridged by four deprotonated carboxyl groups, forming a centrosymmetric paddle-wheel-like structure. Dynamic magnetic property measurements indicate that complex 1 displays field-induced slow magnetic relaxation. The temperature-dependent relaxation times can be fitted using Orbach and Raman processes with parameters of n = 2.8 (2), C = 27 (8) s−1/Kn, τ0 = 5 (2) × 10−10 s and Ueff = 40 (3) cm−1. Magnetic studies on the diamagnetic YIII-diluted analogue [Dy0.206Y1.794(CCA)6 (MeOH)4] (2) reveal its slow magnetic relaxation behavior without external dc field and the antiferromagnetic coupling between the DyIII ions in 1. Fits on the obtained relaxation times of 2 lead to the parameters of n = 4.5 (3), C = 0.7 (2) s−1/Kn, τ0 = 2.8 (2) × 10−9 s and Ueff = 38 (2) cm−1. The results suggest that slow magnetic relaxation originates from the single-ion relaxation of DyIII ions. Moreover, the diamagnetic dilution can suppress other fast relaxation pathways at low temperature, on account of the elimination of magnetic coupling and dipolar interaction. Ab initio calculations were then performed on the single DyIII ion species {YDy} and indicate that the first excited Kramers doublets (KDs) lie at ca. 76 cm−1, which is slightly higher than the experimental Ueff value. The intramolecular magnetic interactions were also calculated and indicate a weak ferromagnetic dipole-diploe magnetic interaction and an antiferromagnetic exchange coupling.

Antiferromagnetic resonance and magnetic anisotropy in PrxY1−xFe3(BO3)4 crystals in the region of the magnetic structure transformation "easy axis – easy plane"

The spin dynamics, magnetic structures and magnetic anisotropy of single crystals Pr x Y 1−x Fe 3 (BO 3 ) 4 have been studied using antiferromagnetic resonance (AFMR) in a wide range of frequencies, magnetic fields, and temperatures. The frequency-field dependences of AFMR for the crystals with x = 0.25 and 0.45 are characteristic of antiferromagnets with the easy plane (EP) anisotropy. The crystals with x = 0.75 and 1.0 exhibit frequency-field dependences that are typical for antiferromagnets with the easy axis (EA) anisotropy. In these crystals, a significant decrease in the effective anisotropy fields of praseodymium upon the transition to the spin-flop state has been found. It is shown that this is the main reason for the large lability intervals, within which the regions of coexistence of the collinear and spin-flop states overlap. In the crystal with x = 0.67, the magnetic field applied along the trigonal axis of the crystal leads to the spin reorientation transition from the EA to the EP state. A magnetic phase diagram of the states on the plane "magnetic field - temperature" is built. In this crystal, the effective anisotropy field of praseodymium also decreases upon the transition to the field-induced EP state. Diamagnetic dilution of the praseodymium subsystem leads to the contribution of this subsystem to the total anisotropy field depending almost linearly on the praseodymium concentration. • In crystal with х = 0.67 magnetic field H||c causes spin reorientation transition EA→EP. • For х = 0.67÷1.0 a decrease in praseodymium anisotropy upon transition to field-induced EP or spin-flop state is found. • Large interval of coexistence of collinear and spin-flop states in crystals with х = 0.75÷1.0

Slow magnetic relaxation in a 3D dysprosium(III)-fluoro-oxalate framework containing zig-zag [Dy–F]n chains

Dysprosium complexes based on [F–Dy] or near-linear [F–Dy–F] unit are of great concern in the field of single-molecule magnets due to their large magnetic anisotropy. Here, the crystal structure and the magnetic relaxation dynamics were reported for a three-dimensional (3D) metal–organic framework (MOF): [DyF(C2O4)(H2O)2]n·2nH2O (1), which is the unique MOF containing zig-zag [Dy–F]n chains. Magnetic susceptibility characterization reveals that 1 is one of the few 3D MOFs which show slow magnetic relaxation under zero dc field. And the effective energy barrier of 72 K for 1 is also higher than most Dy-based 3D MOFs. The diamagnetic ion dilution study shows that the ferromagnetic exchange couplings mainly transmitted by F− bridges in 1 contribute little to the energy barrier, but effectively suppress the quantum tunneling process and result in a smooth hysteresis loop with no waist-restricted step.

Особенности искажения структуры при фазовом переходе в разбавленных кобальтитах YBaCo-=SUB=-4-y-=/SUB=-Zn-=SUB=-y-=/SUB=-O-=SUB=-7+x-=/SUB=- (y=0, 0.3)

Experimental studies of the lattice parameters, thermal expansion, and elastic characteristics in the range of the structural phase transition in the YBaCo4-yZnyO7+x series of cobaltites with diamagnetic dilution of the cobalt subsystem have been carried out. It has been found that for stoichiometric samples annealed in vacuum, the parameter Delta a/a shows no features during the structural transition, while the parameters Delta b/b and Delta c/c experience similar jumps of different signs. This leads to a jump in anisotropic (rhombic) ε0~-4·10^-3 and isotropic (volume change) Delta V/V~ -1·10^-3 deformations. Upon substitution with Zn ions, the orthorhombic distortion of the structure changes slightly, and the jump in the volume anomaly (linear thermal expansion) changes sign. Structure distortion in stoichiometric samples is accompanied by characteristic anomalies in the Young's modulus Delta E(T)/E0 and internal friction in the TS range, while for nonstoichiometric quenched samples, the anomalies completely disappear. The diamagnetic substitution with Zn ions leads to a sharp decrease and then complete disappearance of the jump in the curve Delta E(T)/E0. This may be due to a change in the ratio of isotropic and anisotropic deformation during the structural transition upon a small substitution in the cobalt subsystem.

Features of structure distortion at a phase transition in diluted YBaCo-=SUB=-4-y-=/SUB=-Zn-=SUB=-y-=/SUB=-O-=SUB=-7+x-=/SUB=- (y=0, 0.3) cobaltites

Experimental studies of the lattice parameters, thermal expansion, and elastic characteristics in the range of the structural phase transition in the YBaCo4-yZnyO7+x series of cobaltites with diamagnetic dilution of the cobalt subsystem have been carried out. It has been found that for stoichiometric samples annealed in vacuum, the parameter Delta a/a shows no features during the structural transition, while the parameters Delta b/b and Delta c/c experience similar jumps of different signs. This leads to a jump in anisotropic (rhombic) εo~-4·10-3 and isotropic (volume change) Delta V/V~ -1·10-3 deformations. Upon substitution with Zn ions, the orthorhombic distortion of the structure changes slightly, and the jump in the volume anomaly (linear thermal expansion) changes sign. Structure distortion in stoichiometric samples is accompanied by characteristic anomalies in the Young's modulus Delta E(T)/E0 and internal friction in the TS range, while for nonstoichiometric quenched samples, the anomalies completely disappear. The diamagnetic substitution with Zn ions leads to a sharp decrease and then complete disappearance of the jump in the curve Delta E(T)/E0. This may be due to a change in the ratio of isotropic and anisotropic deformation during the structural transition upon a small substitution in the cobalt subsystem. Keywords: frustrated systems, cobaltites, structural phase transitions, lattice parameters, isotropic deformation, anisotropic deformation, thermal expansion, Young's modulus, internal friction.

In Situ Continuous Wave Electron Paramagnetic Resonance Investigation of the Amyloid Aggregation of Parkinson’s Protein Alpha-Synuclein—the Second Spin-Label Position

Self-aggregation of amyloid proteins is a crucial step in neurodegenerative disease. The protein alpha-synuclein (αS) is implicated in Parkinson’s disease. In an extension of the demonstration of in situ observation of intermediates in αS-aggregation by continuous wave (cw) EPR at room temperature (Zurlo et al. PLoS One 16: e0245548, 2021) by spin-label EPR, here the spin label is attached to position 90 (R1αS90), rather than at position 56. The aim is to determine, if the spin-label position affects the kinetics of aggregation and if local information on the intermediates is accessible. Probed by the MTSL ((1-Oxyl-2,2,5,5-tetramethylpyrroline-3-methyl) methanethiosulfonate) spin label at position 90, using diamagnetic dilution of 9:1 wild type αS to R1αS90, similar aggregation kinetics are found. Rotation correlation times for the spin label in the oligomer cannot be determined with sufficient accuracy to obtain local information on the oligomer under the conditions used. At the present stage, higher resolution EPR approaches, such as high-field EPR are more promising.

Magnetic Relaxation Studies on Trigonal Bipyramidal Cobalt(II) Complexes.

We report the preparation and the full characterization of a novel mononuclear trigonal bipyramidal CoII complex [Co(NS3 iPr )Br](BPh4 ) (1) with the tetradentate sulfur-containing ligand NS3 iPr (N(CH2 CH2 SCH(CH3 )2 )3 ). The comparison of its magnetic behaviour with those of two previously reported compounds [Co(NS3 iPr )Cl](BPh4 ) (2) and [Co(NS3 tBu )Br](ClO4 ) (3) (NS3 tBu =N(CH2 CH2 SC(CH3 )3 )3 ) with similar structures shows that 1 displays a single-molecule magnet behaviour with the longest magnetic relaxation time (0.051 s) at T=1.8 K, which is almost thirty times larger than that of 3 (0.0019 s) and more than three times larger than that of 2 (0.015 s), though its effective energy barrier (26 cm-1 ) is smaller. Compound 1, which contains two crystallographically independent molecules, presents smaller rhombic parameters (E=1.45 and 0.59 cm-1 ) than 2 (E=2.05 and 1.02 cm-1 ) and 3 (E=2.00 and 0.80 cm-1 ) obtained from theoretical calculations. Compounds 2 and 3 have almost the same axial (D) and rhombic (E) parameter values, but present a large difference of their effective energy barrier and magnetic relaxation which may be attributed to the larger volume of BPh4 - than ClO4 - leading to larger diamagnetic dilution (weaker magnetic dipolar interaction) for 2 than for 3. The combination of these factors leads to a much slower magnetic relaxation for 1 than for the two other compounds.

Magnetic field and dilution effects on the slow relaxation of {Er3} triangle-based arsenotungstate single-molecule magnets.

A triangular {Er3} cluster containing polyoxometalate (POM), [Er3(μ3-OH)(H2O)8(AsW9O33)(AsW10O35(dl-mal))]222- (1) (mal = malate), has been obtained via one-pot reactions. Structural analyses demonstrate that three Er3+ ions bridged one μ3-OH to generate a rare μ3-OH-capped triangular {Er3} cluster, which connects two different vacant polyanions to form an unsymmetrical sandwich-type subunit, and adjacent sandwiched subunits are linked through mal ligands to give the targeted dimer. When the Er3+ ions are substituted in whole or in part with Y3+ ions, the diamagnetic yttrium analogue [Y3(μ3-OH)(H2O)8(AsW9O33)(AsW10O35(dl-mal))]222- (2) and diluted sample [Er0.15Y2.85(μ3-OH)(H2O)8(AsW9O33)(AsW10O35(dl-mal))]222- (Er@2) have also been synthesized. Magnetic studies reveal that 1 exhibits field-induced two-step magnetic relaxation processes; the slow relaxation process may arise from intramolecular magnetic interactions, whereas the fast one is likely to originate from the intermolecular dipole-dipole interactions supported by the magnetic results of Er@2. From ab initio calculations, it is found that although the magnetic anisotropies of 1 mainly originate from individual Er3+ fragments, the Er3+-Er3+ interactions have a considerable influence on their slow magnetic relaxation processes.

Optimal diamagnetic dilution concentration for suppressing the dipole-dipole interaction in single-ion magnets.

The effect of screening the CoII moment of monomeric [CoIIL2(H2O)] (L = 8-hydroxyquinaldine), having a trigonal bipyramid coordination, by diamagnetic Zn in CoxZn1-x solid solutions on its magnetic relaxation was explored using ac-susceptibility, high-field electron-spin-resonance measurements and CASPT2 calculations. The retention of the crystal structure for all the solid solutions was demonstrated using single crystal diffraction. The dc-magnetization and theoretical fittings of the susceptibility for Co1 and Co0.1Zn0.9 gave a large zero-field-splitting (ZFS) D of 50 ± 6 cm-1, and very weak dipole interaction between the nearest neighbors, while EPR and calculations confirmed the positive sign of the axial component (D). Consistent parameters were obtained from experiments and theory. Importantly, only field-induced relaxation was observed for the samples with less than 50% Co and a gradual change in the barrier energy to moment reversal and relaxation times was observed between 11% and 20% Co, while both were enhanced for higher dilutions. The results establish a clear barrier for extending the longevity of the magnetism for this type of single-ion species by lowering the intramolecular interactions. The results suggest that the magnetic interaction persists up to the second sphere, that is, for a dilution of 1 in 9 (11% Co). Importantly, this method is applicable to all single-ion magnet systems, that is, the optimum dilution concentration to restrain the dipole field can be given only by the single crystal structure.

Transformation Of Magnetic Transitions and Crystal Structure of NdBaMn2O6 At Diamagnetic Dilution with Ti4+ Ions in the Mn-Sublattice

Magnetic and structural transitions in NdBaMn2−xTixO6 (x = 0, 0.2) samples obtained by the topotactic procedure at 1373 K and lgPO2=−19 atm are studied by low-temperature X-ray diffraction and magnetometry in 1–5 T fields. Undoped double manganite undergoes a reversible ferromagnet—antiferromagnet magnetic phase transition at ТN = 278 K without changing symmetry. The 20 mol.% titanium substitution for manganese causes a decrease in symmetry from the tetragonal space group P4/mmm to the orthorhombic space group Pmmm and a shift of magnetic transitions to lower temperatures. Oxide NdBaMn2O6 demonstrates high values of the magnetocaloric effect in the temperature range 250–315 K.

Magnetic Phase Diagrams of R1 – xSrx(Mn1 – x/2Sbx/2)O3 (R = La, Pr, Nd, Sm, Eu) with Trivalent Manganese Ions

The results of neutron-diffraction, magnetic, and magnetotransport studies of La1 ‒ xSrx(Mn 1- /2 3+ Sb /2 5+ )O3 (x ≤ 0.7) pervoskites, which contain only Mn3+ ions, are reported. It is demonstrated that the system undergoes a transition from the antiferromagnetic state to the ferromagnetic one at x ∼ 0.2. Its structure then changes from O′-orthorombic to O-orthorombic, which is attributable to orbital disordering. At x ≥ 0.6, the competition between antiferromagnetic and ferromagnetic interactions and strong diamagnetic dilution trigger the emergence of the cluster spin-glass phase. As the ionic radius of rare-earth ions in R0.7Sr0.3Mn0.85Sb0.15O3 decreases, the ferromagnetic state transforms gradually into spin glass (R = Sm). All ferromagnetic compositions are dielectric in the magnetically ordered phase with strong magnetoresistive effects. It is assumed that ferromagnetism is induced by the strong covalency and orbital disordering.

Ferromagnetic ordering, magnetic and magnetotransport properties of R1−xSrx(Mn1−x/2Sbx/2)O3 (R = La, Pr, Nd, Sm, Eu) manganites

Neutron diffraction, magnetic and magnetotransport studies of perovskites ( )O3 (R = La, Pr) were carried out. It is shown that for x ∼ 0.2 systems undergo a transition from an antiferromagnetic state (x = 0) to a ferromagnetic state. In the case of the R = La series a structural transformation from the O′-orthorhombic phase (x = 0) to the O-orthorhombic one occurs, which is due to orbital disordering. At x ≥ 0.6 cluster spin glass like phases arise due to the competition between antiferromagnetic and ferromagnetic interactions, as well as due to the strong diamagnetic dilution. In case of the R = Pr series the structural transition into the O-orthorhombic phase was not observed under (Sr, Sb) codoping. As the ionic radius of the rare-earth ion decreases in the series R0.7Sr0.3Mn0.85Sb0.15O3 the crystal structure distortion increases and the ferromagnetic state (R = La, Pr, Nd) is gradually transformed into a spin glass like state (R = Sm, Eu). The ferromagnetic compounds are insulators and exhibit a large magnitude of the magnetoresistance apparently associated with very small amount of Mn4+ ions. The covalent component of the chemical bond and e.g.-orbitals disordering/mixing are assumed to be responsible for ferromagnetism in the compounds under study.

A Pseudo-Octahedral Cobalt(II) Complex with Bispyrazolylpyridine Ligands Acting as a Zero-Field Single-Molecule Magnet with Easy Axis Anisotropy.

The homoleptic mononuclear compound [Co(bpp-COOMe)2 ](ClO4 )2 (1) (bpp-COOMe=methyl 2,6-di(pyrazol-1-yl)pyridine-4-carboxylate) crystallizes in the monoclinic C2/c space group, and the cobalt(II) ion possesses a pseudo-octahedral environment given by the two mer-coordinated tridentate ligands. Direct-current magnetic data, single-crystal torque magnetometry, and EPR measurements disclosed the easy-axis nature of this cobalt(II) complex, which shows single-molecule magnet behavior when a static field is applied in alternating-current susceptibility measurements. Diamagnetic dilution in the zinc(II) analogue [Zn(bpp-COOMe)2 ](ClO4 )2 (2) afforded the derivative [Zn0.95 Co0.05 (bpp-COOMe)2 ](ClO4 )2 (3), which exhibits slow relaxation of magnetization even in zero field thanks to the reduction of dipolar interactions. Theoretical calculations confirmed the overall electronic structure and the magnetic scenario of the compound as drawn by experimental data, thus confirming the spin-phonon Raman relaxation mechanism, and a direct quantum tunneling in the ground state as the most plausible relaxation pathway in zero field.

MAGNETIC PHASE TRANSFORMATIONS IN Sb-SUBSTITUTED RARE-EARTH MANGANITES BASED ON Mn3+ IONS

Neutron diffraction, magnetic and magnetotransport studies of perovskites La 1–x Sr x ( Mn 3+ 1-x/2 Sb 5+ x/2 )O 3 (x ≤ 0,7) containing only Mn3+ ions were carried out. It is shown that at x ~ 0.2, the system goes from the antiferromagnetic state to the ferromagnetic one. In this case, the structure is transformed from the O′-orthorhombic structure to the O-orthorhombic one, which is due to orbital disordering. At x ≥ 0.6, the cluster spin glass phase arises due to the competition between antiferromagnetic and ferromagnetic interactions, as well as due to strong diamagnetic dilution. As the ionic radius of the rare-earth ion is decreased in the series R 0,7 Sr 0,3 Mn 0,85 Sb 0,15 O 3 , the ferromagnetic state is gradually transformed into spin glass (R = Sm). All ferromagnetic compounds are insulators with a large magnitude of the magnetoresistive effect. The high covalence and orbital disordering are assumed to be responsible for ferromagnetism in the compounds under study.

Магнитные фазовые диаграммы R-=SUB=-1-x-=/SUB=-Sr-=SUB=-x-=/SUB=-(Mn-=SUB=-1-x/2-=/SUB=-Sb-=SUB=-x/2-=/SUB=-)O-=SUB=-3-=/SUB=- (R=La, Pr, Nd, Sm, Eu) с ионами марганца в трехвалентном состоянии

AbstractThe results of neutron-diffraction, magnetic, and magnetotransport studies of La_1 ‒ x Sr_ x (Mn _1- x /2 ^3+ Sb _ x /2 ^5+ )O_3 ( x ≤ 0.7) pervoskites, which contain only Mn^3+ ions, are reported. It is demonstrated that the system undergoes a transition from the antiferromagnetic state to the ferromagnetic one at x ∼ 0.2. Its structure then changes from O ′-orthorombic to O -orthorombic, which is attributable to orbital disordering. At x ≥ 0.6, the competition between antiferromagnetic and ferromagnetic interactions and strong diamagnetic dilution trigger the emergence of the cluster spin-glass phase. As the ionic radius of rare-earth ions in R_0.7Sr_0.3Mn_0.85Sb_0.15O_3 decreases, the ferromagnetic state transforms gradually into spin glass (R = Sm). All ferromagnetic compositions are dielectric in the magnetically ordered phase with strong magnetoresistive effects. It is assumed that ferromagnetism is induced by the strong covalency and orbital disordering.

Role of magnetic concentration in modulating the magnetic properties of ultra-small FePt nanoparticles

Magnetic characterization of nanoscale materials is often hindered by the role that sample preparation techniques play in the determination of interparticle interaction strength. Well-dispersed d=2.6(4)nm FePt nanoparticles synthesized by a slight modification of a known polyol synthesis were employed to study this effect at the extreme lower limit of the nanoscale regime. Suspension in a diamagnetic matrix material at varying concentrations was used to characterize the relationships between average particle distance and representative magnetic properties (zero-field cooled/field-cooled (ZFC/FC) magnetization curves, hysteresis M(H) loops at 5K, and ac-susceptibility). By increasing the interparticle distance through diamagnetic dilution, the blocking temperature (TB), anisotropy energy barrier (Ueff), and coercive field (Hc) drop continuously until reaching a dilution ratio where the magnetic signals were limited by the competing diamagnetic contribution from the matrix material. Long-timescale blocking temperature and coercivity are relatively unaffected by particle dilution while the shorter timescale anisotropy energy barrier (Ueff) and attempt time (τ0) are strongly affected. These results demonstrate the need for well-defined sample preparation conditions when comparing materials properties, especially those with applications dependent on superparamagnetism.

Publisher's Note: “Effects of diamagnetic Ga dilution on the Faraday response of bismuth-doped iron garnet films” [Appl. Phys. Lett. 108, 242410 (2016)

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Crystal structure and magnetic properties of Bi1−x Ca x Fe1−x Mn(Ti) x O3 ceramics across the phase boundary

Crystal structure and magnetic properties of BiFeO3 compounds co-doped with Ca and Mn ions as well as Ca and Ti ones were studied using diffraction and magnetometry techniques. Crystal structure of the Bi1−xCaxFe1−xMnxO3 ceramics with x 0.25 show complex magnetic behavior associated with the coexistence of antiferromagnetic matrix and magnetic clusters. Compounds co-doped with Ca and Ti ions with rhombohedral structure testify nearly three times larger remnant magnetization as compared with that observed for Ca|Mn-doped series, and magnetic state of the compounds with x > 0.1 remains to be homogeneous weak ferromagnetic one up to x ~ 0.3, and above this concentration, magnetic structure is disrupted because of diamagnetic dilution.

Transformation from an easy-plane to an easy-axis antiferromagnetic structure in the mixed rare-earth ferroborates PrxY1−xFe3(BO3)4: magnetic properties and crystal field calculations

The magnetic structure of the mixed rare-earth system PrxY1−xFe3(BO3)4 (x = 0.75, 0.67, 0.55, 0.45, 0.25) was studied via magnetic and resonance measurements. These data evidence the successive spin reorientation from the easy-axis antiferromagnetic structure formed in PrFe3(BO3)4 to the easy-plane one of YFe3(BO3)4 associated with the weakening of the magnetic anisotropy of the Pr subsystem due to its diamagnetic dilution by nonmagnetic Y. This reorientation occurs through the formation of an inclined magnetic structure, as was confirmed by our previous neutron research in the range of x = 0.67 ÷ 0.45. In the compounds with x = 0.75 and 0.67 whose magnetic structure is close to the easy-axis one, a two-step spin reorientation takes place in the magnetic field H||c. Such a peculiarity is explained by the formation of an interjacent inclined magnetic structure with magnetic moments of Fe ions located closer to the basal plane than in the initial state, with these intermediate states remaining stable in some ranges of the magnetic field.An approach based on a crystal field model for the Pr3+ ion and the molecular-field approximation is used to describe the magnetic characteristics of the system PrxY1−xFe3(BO3)4. With the parameters of the d–d and f–d exchange interactions, of the magnetic anisotropy of the iron subsystem and of the crystal field parameters of praseodymium thus determined, it is possible to achieve a good agreement between the experimental and calculated temperature and field dependences of the magnetization curves (up to 90 kOe) and magnetic susceptibilities (2–300 K).