Dc Magnetic Susceptibility Research Articles

A series of dinuclear lanthanide complexes derived from a hydroxyl-rich ligand: {Dy2} exhibiting single-molecule magnet behaviour

Seven dinuclear lanthanide complexes of formulae Ln2L2 (Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5)), Ho2L2·MeCN (6) and Er2L2·MeCN (7) (H3L = 2-{[bis(2-hydroxy-3-ethoxybenzyl)(aminoethyl)amino]methyl}phenol) have been synthesized by the reactions of Ln(NO3)3∙6H2O with the hydroxyl-rich ligand H3L in MeCN/NEt3 solution. The structures of the isostructural complexes 1–7 were determined by single-crystal X-ray crystallography. X-ray crystallography analyses reveal that each compound is neutral and consists of two metal centers and two triply-deprotonated ligands. The two Ln(III) atoms in 1–7 are doubly bridged by two phenolato oxygen atoms of two L3− ligands. Each of the two lanthanide ions is seven-coordinated and possesses capped trigonal prism geometry. Dc magnetic susceptibility studies in the 2–300 K range reveal probably weak antiferromagnetic interaction for 3–7. Complex 5 exhibits frequency dependence of the ac-susceptibility typical of single-molecule magnets.

Anisotropic re-entrant spin-glass features in a metallic kagome lattice, Tb3Ru4Al12

We present the results of ac and dc magnetic susceptibility and isothermal magnetization measurements (T = 2–300 K) on the single crystals of a metallic kagome lattice, Tb3Ru4Al12, reported recently to undergo reentrant magnetism with the onset of long range antiferromagnetic order below (TN =) 22 K. The magnetization data obtained on the crystal with the c-axis orientation along magnetic-field reveal spin-glass-like characteristics near 17 K (below TN). However, for the orientation along basal plane, such glassy anomalies are not observable above 2 K. In this respect, this compound behaves like an ‘anisotropic’ re-entrant spin-glass. Possible implications of this finding to the field of 'geometrically frustrated magnetism' are considered.

Magnetic field induced evolution of highly resistant Griffiths phase in fine grain manganite La0.75Ca0.25MnO3

Abstract The Griffiths phase in fine grain manganite La0.75Ca0.25MnO3 is studied by the complementary structural methods, DC magnetic susceptibility and ESR spectroscopy. The Griffiths like phase is detected above Curie temperature between 232 and 280 K and sustains up to high magnetic field of 3000 Oe. The magnetic susceptibility of Griffiths phase is a decreasing function of temperature. The magnetic field dependence of Griffiths phase susceptibility reveals its remarkable contribution to measured total susceptibility. The additional anomalous ESR signal supperimpossed on the paramagnetic one is ascribed to the locally inhomogeneous Griffiths like phase in agreement with the core – shell model.

Unusual Methylenediolate Bridged Hexanuclear Ruthenium(III) Complexes: Syntheses and Their Application.

Three structurally analogous hexanuclear ruthenium(III) complexes were isolated with the general molecular formula of [Ru6III(O)2(μ4-η2-η2-CH2O2)( t-BuCO2)12(L)2] where L = pyridine (1) or 4-dimethylamino pyridine (DMAP; 2) or 4-cyanopyridine (3). Complexes 1 and 3 were solved in the tetragonal I4̅c2 and P41212 space group, respectively, while 2 crystallized in the monoclinic system with P21 /c space group. In all three complexes, two oxo-centered Ru(III) triangles were bridged by a unique and a rare methylenediolate (CH2O2)2-) ligand. This (CH2O2)2- group is reported to be an intermediate, which is not isolated in its metal-free form, to date, as it is unstable. Control experiments performed evidently reveal that the unique reaction condition followed is mandatory to isolate 1-3 and the origin of (CH2O2)2- is unknown at the moment, as no precursor was used to form this intermediate. The presence of (CH2O2)2- identified through X-ray diffraction was further unambiguously confirmed by various 1D (1H and 13C) and 2D-NMR (HSQC, TOCSY, NOESY, and DEPT) spectroscopies. Direct current (dc) magnetic susceptibility measurements performed on 1 and 2 reveal the predominant antiferromagnetic exchange interaction between the Ru(III) centers result in a diamagnetic ground state at 2.0 K. The paramagnetic influence of 1-3 at room temperature evidently felt by the 1H nuclei of the (CH2O2)2- unit predominates compared to other NMR active nuclei in the complexes. The presence of an electron donating or withdrawing substituent on the terminal pyridine results in significant change in the dihedral angle of two oxo-centered triangular (Ru3O-) planes. The change in the structural parameters of 1-3 due to the substituents markedly reflected on the absorption profile and redox behavior, which are systematically investigated. Preliminary galvanostatic charge/discharge cycling experiments performed on a representative complex (3) suggest that 3 can be a promising candidate to employ as an effective multiple electron charge carrier in a nonaqueous redox flow battery.

Magnetic and electrical properties of R5Ir3 (R = Tb, Er)

Magnetic and electrical properties of R5Ir3 (R = Tb, Er) polycrystals with hexagonal structure have been studied by measuring magnetization, dc magnetic susceptibility, and electrical resistivity. Tb5Ir3 shows reentrant magnetism; it possesses ferromagnetic state below TC = 49 K and antiferromagnetic state takes place at Tt = 6.5 K. In the antiferromagnetic state, irreversible magnetic field-induced antiferromagnetic to ferromagnetic transition was observed. Meanwhile, Er5Ir3 shows ferromagnetic property below TC = 10 K; antiferromagnetic state exists below Tt = 2.1 K. In the low temperature antiferromagnetic state, the irreversible antiferromagnetic to ferromagnetic transition was also observed. Paramagnetic susceptibility shows Curie-Weiss behavior in both compounds; the effective magnetic moment is in good agreement with the theoretical values of Tb3+ and Er3+ ions. Electrical resistivity indicated the metallic property; distinct anomalies were observed at the transition temperatures for both compounds.

Magnetic frustration in lyonsite-type vanadates in FeVO4–Co3V2O8 system

Six phases crystallizing in the lyonsite-type structure were synthesized by solid-state reaction between nFeVO4 and (1–n)Co3V2O8, where n = 0.73, 0.7143, 0.6667, 0.5843, 0.57, and 0.56. DC magnetic susceptibility in high-temperature range (T > 100 K) was found to follow the Curie–Weiss law with negative and large value of the Curie–Weiss temperature. The effective magnetic moments were slightly bigger than for high-spin Co2+ and Fe3+ ions. Spin-glass-like features observed in magnetic FC/ZFC susceptibilities at low temperatures (T < 15 K) could be the result of a huge magnetocrystalline anisotropy of randomly oriented crystallites or magnetic nanoclusters in the powder samples, or they could be due to magnetic frustration arising from competition of ferromagnetic (FM) and antiferromagnetic (AFM) exchange interactions. The presence of FM component with a large coercive field and strong magnetic remanence in samples with large Co content was evidenced at low temperature. Weak and very broad electron paramagnetic resonance (EPR) spectra were analyzed by decomposition on Lorentzian components and were attributed to magnetic spin clusters or metallic precipitates not involved in bulk magnetism registered in magnetization measurements. In addition, for n = 0.7143, 0.6667 samples, the much narrower line was due to the V4+ magnetic defects connected with oxygen vacancies.

Functionalization and Magnetic Relaxation of Ferrite Nanoparticles for Theranostics

Magnetic nanoparticles have drawn attention recently due to their interesting nanoscopic features and potential applications. Various kinds of ferrite nanoparticles with diameters between 3 and 34 nm encapsulated by amorphous SiO2 were functionalized and examined for biomedical applications. From dc and ac magnetic susceptibility measurements, it was found that these particles followed the Neel relaxation system. Co–Zn ferrite (Co0.8Zn0.2Fe2O4) nanoparticles were prepared and the increase in temperature in the ac field was estimated for hyperthermia treatment. In vitro experiments using cultured human breast cancer cells were carried out, and a dramatic hyperthermia effect was observed. As one of the diagnostic methods, magnetic resonance (MR) measurements were performed for CoFe2O4 nanoparticles, and the samples were also evaluated as potential contrast media for MR imaging.

A New {Dy5} Single-Molecule Magnet Bearing the Schiff Base Ligand N-Naphthalidene-2-amino-5-chlorophenol

A new {Dy5} cluster compound has been synthesized and structurally characterized from the initial use of the Schiff base ligand N-naphthalidene-2-amino-5-chlorophenol (nacpH2) in coordination chemistry. The 1:1 reaction between Dy(hpd)3∙2H2O and nacpH2, in a solvent mixture comprising CH2Cl2 and MeOH, afforded orange crystals of [Dy5(OH)2(hpd)3(nacp)5(MeOH)5] (1) in 70% yield, where hpd− is the anion of 3,5-heptadione. The {Dy5} complex can be described as two vertical {Dy3(μ3-OH)}8+ triangles sharing a common vertex; such a metal topology is unprecedented in 4f-metal cluster chemistry. Direct current (dc) magnetic susceptibility studies revealed the presence of some weak ferromagnetic exchange interactions between the five DyIII ions at low temperatures. Alternating current (ac) magnetic susceptibility measurements at zero applied dc field showed that complex 1∙3MeOH∙CH2Cl2 exhibits temperature- and frequency-dependent out-of-phase signals below ~20 K, characteristics of a single-molecule magnet (SMM). The resulting relaxation times were used to construct an Arrhenius-type plot and determine an effective energy barrier, Ueff, of 100 K for the magnetization reversal. The application of a small dc field of 200 Oe resulted in the surpassing of the quantum tunneling process and subsequently the increase of the Ueff to a value of 170 K. The reported results are part of a long-term program aiming at the preparation of structurally and magnetically interesting lanthanide complexes bearing various Schiff base chelating/bridging ligands.

Anomalous magnetic properties of CaRuO3 probed by AC and DC magnetic measurements and by low Ti impurity doping

Calcium ruthenate ($CaRuO_3$) is widely believed to be located close to a quantum critical point due to the strong non-Fermi-liquid behavior expressed in the temperature dependence of electronic transport, specific heat, optical conductivity, etc. However, the corresponding anomalous behavior, marking crossover temperature regimes in the magnetic response of $CaRuO_3$, is still lacking. Here we report detailed AC and DC magnetic susceptibility measurements of $CaRuO_3$ and $CaRu_{0.97}Ti_{0.03}O_3$. The AC magnetic susceptibility measurements of the $CaRuO_3$ show a slight dependence on the frequency of AC magnetic field below ~ 40 K, and an additional subtle change of curvature around 12 K. We interpret these results as a critical slowing down of spin fluctuations towards T=0 K. We confirm these observations by magnetic measurements of $CaRu_{0.97}Ti_{0.03}O_3$, which show a pronounced magnetic response corresponding to the above temperatures.

Field‐induced Slow Magnetic Relaxation Behavior in a Mononuclear Dy(III) Complex based on 8‐Hydroxyquinoline Derivate Ligand

A mononuclear DyIII compound [Dy(quinbeyz)(NO3)2(DMF)] (1) based on 8‐hydroxyquinoline derivative ligand [quinbeyz = 8‐hydroxyquinoline‐2‐carboxyaldehyde‐(benzoyl)hydrazine] was synthesized and characterized by single‐crystal X‐ray diffraction analysis. The crystal structure showed that the DyIII ion of the compound is nine‐coordinate in a distorted capped square antiprism arrangement with pseudo‐C4v symmetry. Direct‐current (dc) magnetic susceptibilities revealed that compound 1 showed easy axial magnetic anisotropy. The crystal field parameters (CFPs) were obtained from fitting of the magnetic data, and the orientation of the magnetic easy axis of the central DyIII atom for compound 1 was calculated by the electrostatic model. It can be helpful further to understand the magnetic anisotropy of DyIII and the magneto‐structural relationship. Alternating current (ac) magnetic measurements demonstrated that compound 1 exhibited field‐induced slow magnetic relaxation behavior. These results demonstrated that an approach to achieve mononuclear lanthanide single‐molecule magnets (SMMs) with pseudo‐C4v symmetry could be effectively constructed by using 8‐hydroxyquinoline derivative ligand.

Ferrimagnetic cluster formation due to oxygen vacancies inCaFe2O4−δ

${\mathrm{CaFe}}_{2}{\mathrm{O}}_{4}$ possesses an intriguing crystal structure characterized by the presence of ${\mathrm{FeO}}_{6}$ octahedra that share both edges and corners, and featuring zigzag Fe chains that are assembled in a honeycomb tube network. The nominal ${\mathrm{CaFe}}_{2}{\mathrm{O}}_{4}$ has been identified to show a long-range antiferromagnetic spin ordering of N\'eel temperature ${T}_{N}\phantom{\rule{4pt}{0ex}}\ensuremath{\sim}184$ K. From dc and ac magnetic susceptibility measurements on both polycrystalline and single-crystal samples, a random distribution of ferrimagnetically ordered clusters of Fe spins is proposed to exist in the oxygen deficient ${\mathrm{CaFe}}_{2}{\mathrm{O}}_{4\ensuremath{-}\ensuremath{\delta}}$. The ferrimagnetic ordering is proposed, coming from the oxygen vacancy-induced ${\mathrm{Fe}}^{3+}$ to ${\mathrm{Fe}}^{2+}$ conversion for the antiferromagnetically coupled spins of ${\mathrm{Fe}}^{2+}$ ions in the low-spin state and the ${\mathrm{Fe}}^{3+}$ ions in the high-spin state, which leads to an incomplete cancellation of staggered magnetization below ${T}_{N}$. Current model reasonably explains the inconsistencies found in the literature regarding the persistent ferromagnetic component for ${\mathrm{CaFe}}_{2}{\mathrm{O}}_{4}$, having a confirmed antiferromagnetic long-range spin ordering from neutron diffraction studies. We calculate the antiferromagnetic spin structure and the parameters of a Heisenberg Hamiltonian via spin-polarized density functional theory, obtaining results that are consistent, to a very high degree, with our experimental results for ac and dc magnetic susceptibility.

EPR and Magnetometry of Mixed Phases in FeVO4\u2013Co3V2O8 System

Magnetic properties of five samples obtained in reactions between nFeVO4 and (1 − n)Co3V2O8 (with the composition index n = 0.54, 0.50, 0.40, 0.30 and 0.20) have been investigated by dc magnetometry and electron paramagnetic resonance (EPR). The investigated samples contained two phases: one having lyonsite-type structure and the other Co3V2O8. Temperature dependence of dc magnetic susceptibility showed the Curie–Weiss paramagnetic behaviour with a strong antiferromagnetic (AFM) interaction in the high-temperature range leading to magnetic transitions at 6 and 12 K. For all samples, the magnetic hysteresis loop in isothermal magnetisation was registered at T = 5 K indicating the existence of a ferromagnetic component. Samples n = 0.54 and 0.50 displayed a large coercive field and remanent magnetisation in contrast to the other three samples due to higher content of the lyonsite-type structure. EPR spectra of the studied samples showed a broad asymmetric line that was decomposed on lorentzian or gaussian components. Temperature dependence of the spectral parameters (resonance field, linewidth, integrated intensity) of these components was studied in high-temperature range (T > 90 K). The observed spectra were attributed to different types of magnetic spin clusters.

Does Symmetry Influence the Properties of [MnIII6CrIII]3+ Single‐Molecule Magnets?

The triplesalen complex [MnIII6CrIII](ClO4)3 was synthesized and characterized by single‐crystal X‐ray diffraction, UV/Vis/NIR spectroscopy, and DC and AC magnetic susceptibilities. The molecular structure is D3 symmetric, whereas all other salts and solvates of [MnIII6CrIII]3+ are S6 symmetric. The UV/Vis/NIR spectrum of D3 symmetric [MnIII6CrIII]3+ is almost identical to that of S6 symmetric [MnIII6CrIII]3+ demonstrating that the electronic structure is not significantly perturbed by the symmetry variation. The magnetic data of D3 symmetric [MnIII6CrIII]3+ is also similar to those of S6 symmetric [MnIII6CrIII]3+ with antiferromagnetic JMn–Mn exchange coupling. This is in contrast to the ferromagnetic JMn–Mn exchange coupling in the chiral RR[MnIII6CrIII]3+ synthesized with a chiral triplesalen derivative. Due to the chirality, RR[MnIII6CrIII]3+ is also of D3 symmetry. However, its UV/Vis/NIR spectrum differs to those of D3 and S6 symmetric [MnIII6CrIII]3+. This indicates that the electronic and magnetic properties of RR[MnIII6CrIII]3+ are not different to those of [MnIII6CrIII]3+ due to the symmetry variation but due to the specific properties of the two triplesalen ligands.

Family of [Ln4Mn8] (Ln = Gd, Tb, Dy, Ho) and Y4Mn8 single-molecule magnets from the use of 2-(pyridine-2-yl)propan-2-ol

The syntheses, structures and magnetic properties are reported of a new family of [Ln4Mn8O8(O2CPh)16(dmhmp)4] (Ln = Gd (1), Tb (2), Dy (3), Ho (4)) complexes obtained from the use in Mn–Ln chemistry of 2-(pyridine-2-yl)propan-2-ol (dmhmpH), a bulkier derivative of 2-(hydroxymethyl)pyridine (hmpH) containing a CMe2OH arm instead of CH2OH. Complexes 1–4 were obtained from the reaction of Mn(O2CPh)2, Ln(NO3)3, dmhmpH and NEt3 in a 2:1:2:4 molar ratio in MeCN/MeOH (24:2 mL), and the corresponding reaction with Y(NO3)3 gave [Y4Mn8O8(O2CPh)16(dmhmp)4] (5). The crystal structures of representative complexes 1 and 5 were solved and they are isostructural, with centrosymmetric structures comprising five metal-containing layers in an ABCBA arrangement, with A = Gd(Y), B = Mn2Gd(Y), and C = Mn4. Variable-temperature, solid-state dc and ac magnetic susceptibility studies on 1–5 revealed dominant antiferromagnetic interactions between the Mn8 unit and the LnIII ions. The data for 5 ostensibly indicated a well-isolated singly-degenerate ground state, but further studies suggested instead that the ground state is an S = 5 state that is near-degenerate with one or more states with S ≤ 4. Frequency-dependent ac in-phase χ′MT and out-of-phase χ″M signals indicate 3 (Dy) to possibly be an SMM, and this was confirmed by observation of hysteresis loops below 1.6 K in magnetization versus dc field scans below 2 K.

Abrupt Spin Crossover Behavior in a Linear N1,N2-Triazole Bridged Trinuclear Fe(II) Complex

The synthesis, structures and magnetic properties of a new trinuclear spin crossover complex [FeII3(pyrtrz)6(TsO)6]·10H2O·2CH3OH (C2) and its analogue binuclear [FeII2(pyrtrz)5(SCN)4]·7H2O (C1), are reported here. These two compounds are synthesized based on the pyrrolyl functionalized Schiff base 1,2,4-triazole ligand 4-((1H-pyrrol-2-yl)methylene-amino)-4H-1,2,4-triazole (pyrtrz), which represent rare discrete multi-nuclear species, with µ2-N1,N2-triazole bridges linking the FeII centers. DC magnetic susceptibility measurements revealed an abrupt single-step spin crossover (SCO) behavior for compound 2 on the central FeII site and single-crystal X-ray diffraction (173 K) showed that this compound crystallizes in the monoclinic space group (P21/c), and multiple intramolecular interactions were found responsible for the abrupt transition. Compound 1 is a binuclear complex with thiocyanate as terminal ligands. This compound stays in high spin state over the whole temperature range and displays weak antiferromagnetic exchange coupling.

Filled skutterudite superconductor CaOs4P12 prepared by high-pressure synthesis

In this paper, we report the transport, thermodynamic, and superconducting properties of a new filled skutterudite ${\mathrm{CaOs}}_{4}{\mathrm{P}}_{12}$ synthesized under high pressure and high temperature. The electrical resistivity of 3.4--4.$8\mathrm{m}\mathrm{\ensuremath{\Omega}}\mathrm{cm}$, carrier concentration of 3.8--6.$1\ifmmode\times\else\texttimes\fi{}\phantom{\rule{4pt}{0ex}}{10}^{20}{\mathrm{cm}}^{\ensuremath{-}3}$, and positive Hall coefficient suggest that ${\mathrm{CaOs}}_{4}{\mathrm{P}}_{12}$ is a semimetal with hole carriers. An anomaly due to low-energy optical modes corresponding to an Einstein temperature of 150 K was observed in the specific heat. Resistivity, dc magnetic susceptibility, and specific heat measurements indicate bulk superconductivity below 2.5 K. The specific heat anomaly at ${T}_{\mathrm{c}},\mathrm{\ensuremath{\Delta}}C/\ensuremath{\gamma}{T}_{\mathrm{c}}\phantom{\rule{4pt}{0ex}}\ensuremath{\approx}1.4$, is in agreement with the Bardeen-Cooper-Schrieffer (BCS) value of 1.43. The electron-phonon coupling constant ${\ensuremath{\lambda}}_{ep}$ is estimated to be 0.47. ${\mathrm{CaOs}}_{4}{\mathrm{P}}_{12}$ is classified as a BCS-type, weakly coupled type-II superconductor with an upper critical field of ${H}_{\mathrm{c}2}\phantom{\rule{4pt}{0ex}}\ensuremath{\approx}22$ kOe and Ginzburg-Landau coherence length of $\ensuremath{\xi}\phantom{\rule{4pt}{0ex}}\ensuremath{\approx}12$ nm.

Synthesis, structure and magnetic properties of three CuII2LnIII complexes (Ln = Pr, Nd and Sm) with an unsymmetrical Schiff base ligand

Three heterometallic trinuclear complexes of general formula, [{(CH3CN)CuL}2(µ-NO3)2Ln(NO3)] [Ln = Pr (1), Nd (2) and Sm (3)] have been synthesized by reacting a neutral metalloligand [CuL], derived from a N2O2 donor unsymmetrically di-condensed di-Schiff base, H2L (where H2L = N-α-methylsalicylidene-N΄-salicylidene-1,3-propanediamine) with the respective lanthanide nitrates in 2:1 ratios. X-ray single-crystal structure reveals that these isomorphic complexes (1–3) possess C2-symmetric trinuclear units where two terminal metalloligands are coordinated to the central Ln(III) ion in transoid manner. In all three complexes, distorted tetradecahedron coordination geometry is formed around the Ln(III) ion by four μ2-phenoxido oxygen atoms from two (CuL) units and three chelating nitrato coligands. The two terminal Cu(II) ions possess distorted octahedral geometry. The dc magnetic susceptibilities and field dependent magnetization measurements of all three complexes reveal the occurrence of antiferromagnetic interactions between Cu(II) and Ln(III) ions.

Synthesis, structure and magnetic properties of two new 3d-3d′-4f clusters of NiIIHoIIIMIII (M = Fe, Co)

Two new 3d-3d′-4f complexes, [Ni(L)Ho(H2O)4][Co(CN)6]·3H2O (1) and [Ni(L)Ho(H2O)4][Fe(CN)6]·3H2O (2) (H2L = N,N′-bis(3-methoxysalicylaldiimine)ethylene) were synthesized and characterized, the X-ray measurements indicated that complexes 1 and 2 are trinuclear clusters and they are isostructural. The magnetic analysis revealed that the NiII ion is diamagnetic, and a comparison of their dc (direct current) magnetic susceptibilities indicated that the magnetic coupling between HoIII and FeIII mediated by cyanide bridges is insignificant. The two complexes can indeed help us understand the magnetic coupling behavior within complicated spin systems such as 3d-3d′-4f.

Series of Single-Ion and 1D Chain Complexes Based on Quinolinic Derivative: Synthesis, Crystal Structures, HF-EPR, and Magnetic Properties.

By utilizing the quinolinic derivative, 8-carboxymethoxy-2-carboxylicquinoline (L), five transition metal coordination complexes, [M(L)(H2O)3]·H2O] (M = Mn (1), Co (2)), [Ni(L)(H2O)2] (3), and {[M(L)](H2O)} n (M = Ni (4), Cu (5)), were synthesized by hydrothermal methods employing similar synthetic strategies. The crystal structures, magnetism and high-field EPR were characterized for the obtained compounds. 1-3 are mononuclear compounds. 1 and 2 have pentagonal bipyramidal geometry, while 4 and 5 exhibit one-dimensional zig-zag chain. Direct current magnetic and EPR studies demonstrate that compound 2 has large and positive D value (∼70.4 cm-1), indicating the easy plane magnetic anisotropies of 2. This D value is the largest one in the reported Co(II) complexes with pentagonal bipyramidal geometry. Field-induced slow magnetic relaxation behavior was observed for 2 by the dynamic ac magnetic susceptibility measurements. The dc magnetic susceptibility studies of 4 and 5 give similar weak MII-MII antiferromagnetic interactions ( J = -1.50 and -3.55 K for 4 and 5, respectively). High-field EPR results show that 4 can be considered as a quantum antiferromagnet.

Spin-glass behavior in a binary Pr3Ir intermetallic compound

Polycrystalline Pr3Ir was synthesized by arc melting. Its cementite-type crystal structure (Pnma) was confirmed by powder X-ray diffraction and estimated lattice parameters are in agreement with literature. Physical properties were measured by means of the ac and dc magnetic susceptibility, electrical resistivity and heat capacity. Our results indicate spin-glass behavior in Pr3Ir with a freezing temperature Tf = 6.58 K and activation energy Ea = 2.17 kBTf. Above Tf, the dc magnetic susceptibility of Pr3Ir follows a modified Curie-Weiss dependence with a paramagnetic Curie temperature θP = 3.4 K and an effective magnetic moment μeff = 3.72 (1) μB/Pr that is somewhat larger than expected for Pr+3 (μeff = 3.5 μB/Pr). Resistivity measurement shows that Pr3Ir is a poor metal with a residual resistivity ratio about 1.6. The spin-glass scenario in Pr3Ir likely originates from the dynamic fluctuations of the magnetic interactions, as it was proposed for stoichiometric, well ordered PrAu2Si2 Pr-based ternary compound.