ChemInform Abstract: Multiple Magnetic Phase Transitions in CePd2In4.

The metallic compound EuCo2P2 with the body-centered tetragonal ThCr2Si2 structure containing Eu spins 7/2 was previously shown from single-crystal neutron diffraction measurements to exhibit a helical antiferromagnetic (AFM) structure below TN = 66.5 K with the helix axis along the c axis and with the ordered moments aligned within the ab-plane. Here we report crystallography, electrical resistivity, heat capacity, magnetization and magnetic susceptibility measurements on single crystals of this compound. We demonstrate that EuCo2P2 is a model molecular-field helical Heisenberg antiferromagnet from comparisons of the anisotropic magnetic susceptibility chi, high-field magnetization and magnetic heat capacity of EuCo2P2 single crystals at temperature T < TN with the predictions of our recent formulation of molecular field theory. Values of the Heisenberg exchange interactions between the Eu spins are derived from the data. The low-T magnetic heat capacity ~ T^3 arising from spin-wave excitations with no anisotropy gap is calculated and found to be comparable to the lattice heat capacity. The density of states at the Fermi energy of EuCo2P2 and the related compound BaCo2P2 are found from the heat capacity data to be large, 10 and 16 states/eV per formula unit for EuCo2P2 and BaCo2P2, respectively. These values are enhanced by a factor of ~2.5 above those found from DFT electronic structure calculations for the two compounds. The calculations also find ferromagnetic Eu-Eu exchange interactions within the ab-plane and AFM interactions between nearest- and next-nearest planes, in agreement with the MFT analysis of chi{ab}(T < TN).

We report the synthesis and the magnetic properties of single crystalline CeRhAl$_4$Si$_2$ and CeIrAl$_4$Si$_2$ and their non magnetic La-analogs. The single crystals of these quaternary compounds were grown using Al-Si binary eutectic as flux. The anisotropic magnetic properties of the cerium compounds were explored in detail by means of magnetic susceptibility, isothermal magnetization, electrical resistivity, magnetoresistivity and heat capacity measurements. Both CeRhAl$_4$Si$_2$ and CeIrAl$_4$Si$_2$ undergo two antiferromagnetic transitions, first from the paramagnetic to an antiferromagnetic state at $T_{\rm N1}$~=~12.6~K and 15.5~K, followed by a second transition at lower temperatures $T_{\rm N2}$~=~9.4~K and 13.8~K, respectively. The paramagnetic susceptibility is highly anisotropic and its temperature dependence in the magnetically ordered state suggests the $c$-axis to be the relatively easy axis of magnetization. Concomitantly, isothermal magnetization at 2~K along the $c$-axis shows a sharp spin-flop transition accompanied by a sizeable hysteresis, while it varies nearly linearly with field along the [100] direction up to the highest field 14~T, of our measurement. The electrical resistivity provides evidence of the Kondo interaction in both compounds, inferred from its $-lnT$ behavior in the paramagnetic region. The heat capacity data confirm the bulk nature of the two magnetic transitions in each compound, and further confirm the presence of Kondo interaction by a reduced value of the entropy associated with the magnetic ordering. From the heat capacity data below 1~K, the coefficient of the linear term in the electronic heat capacity, $\gamma$, is inferred to be 195.6 and 49.4~mJ/mol K$^2$ in CeRhAl$_4$Si$_2$ and CeIrAl$_4$Si$_2$, respectively classifying these materials as moderate heavy fermion compounds.

Multiple magnetic phase transitions in CePd2In4

Magnetic, thermal and electrical properties of Er 3Co studied on single crystals

A polycrystalline sample of superconducting $\mathrm{ThI}{\mathrm{r}}_{3}$ was obtained by arc-melting Th and Ir metals. Powder x-ray diffraction revealed that the compound crystalizes in a rhombohedral crystal structure (R-3m, s.g. #166) with the lattice parameters: $a=5.3394(1)\phantom{\rule{0.16em}{0ex}}\AA{}$ and $c=26.4228(8)\phantom{\rule{0.16em}{0ex}}\AA{}$. Normal and superconducting states were studied by magnetic susceptibility, electrical resistivity, and heat capacity measurements. The results showed that $\mathrm{ThI}{\mathrm{r}}_{3}$ is a type-II superconductor (Ginzburg-Landau parameter $\ensuremath{\kappa}=38)$ with the critical temperature ${T}_{\mathrm{c}}=4.41\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. The heat capacity data yielded the Sommerfeld coefficient $\ensuremath{\gamma}=17.6\phantom{\rule{0.16em}{0ex}}\mathrm{mJ}/(\mathrm{mo}\mathrm{l}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{2})$ and the Debye temperature ${\mathrm{\ensuremath{\Theta}}}_{\mathrm{D}}=169\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. The ratio $\mathrm{\ensuremath{\Delta}}C/(\ensuremath{\gamma}{T}_{\mathrm{c}})=1.6$, where $\mathrm{\ensuremath{\Delta}}C$ stands for the specific heat jump at ${T}_{\mathrm{c}}$, and the electron--phonon coupling constant ${\ensuremath{\lambda}}_{e\ensuremath{-}p}=0.74$ suggest that $\mathrm{ThI}{\mathrm{r}}_{3}$ is a moderate-strength superconductor. The experimental studies were supplemented by band structure calculations, which indicated that the superconductivity in $\mathrm{ThI}{\mathrm{r}}_{3}$ is governed mainly by $5d$ states of iridium. The significantly smaller band-structure value of Sommerfeld coefficient as well as the experimentally observed quadratic temperature dependence of resistivity and enhanced magnetic susceptibility suggest the presence of electronic interactions in the system, which compete with superconductivity.

We present electron spin resonance (ESR) measurements in single-crystalline samples of EuIn${}_{2}$As${}_{2}$ grown using the In-flux method. This compound crystallizes in a hexagonal P6(3)/$mmc$ structure and presents antiferromagnetic (AFM) ordering below ${T}_{N}=16$ K. In the paramagnetic state, a single Eu${}^{2+}$ Dysonian ESR line with nearly temperature-independent $g$-factor and linewidth is observed, indicating the absence of Korringa-like relaxation of the Eu${}^{2+}$ ions. Approaching the AFM transition, we observe an anisotropic $g$-shift and a linewidth broadening which has a maximum at ${T}_{N}$, suggesting that the short-range AFM correlation dominates the spin dynamics of the Eu${}^{2+}$ spins in this temperature range. Our results are discussed based on complementary data (magnetic susceptibility, heat capacity, and electrical resistivity measurements) that provide further details about the global macroscopic physical properties of the EuIn${}_{2}$As${}_{2}$ intermetallic compound.

Lanthanide ($Ln$) based $Ln\mathrm{SbTe}$ materials have garnered significant attention due to the rich interplay of long-range magnetic ordering and topological properties, driven by unique crystalline symmetry, $4f$ electron interactions, and pronounced spin-orbit coupling (SOC) effects. DySbTe, as a heavier lanthanide based member of the $Ln\mathrm{SbTe}$ family, stands out with its SOC and larger on-site interactions on its $4f$ electrons, which arise due to the heavier Dy element. Here, we present a comprehensive study on the low-temperature bulk physical properties and the electronic structure of DySbTe using magnetic susceptibility, heat capacity, and electrical resistivity measurements, along with high-resolution angle-resolved photoemission spectroscopy (ARPES), scanning tunneling microscopy and spectroscopy (STM/S), and density functional theory calculations. Our thermodynamic measurements revealed an antiferromagnetic ordering below ${T}_{\mathrm{N}}=7.45$ K and a subsequent magnetic phase transition at ${T}_{\mathrm{N}1}=7.15$ K. Our transport studies indicate a semimetallic behavior with unusual feature in the ordered state. Our ARPES measurements revealed a diamond-shaped Fermi pocket centered at the $\overline{\mathrm{\ensuremath{\Gamma}}}$ point, with band features that evolve distinctly across various binding energies. STM/S results indicate a minimum in the density of states at around 100 meV below the Fermi level, and ARPES measurements reveal a significant gap present around the $\overline{\mathrm{X}}$ point, differentiating DySbTe from other $Ln\mathrm{SbTe}$ compounds. These findings enhance our understanding of the SOC effects on the electronic structure and topological properties in the $Ln\mathrm{SbTe}$ family, highlighting DySbTe as a promising candidate for exploring the interplay between topology and magnetism.

Crystal structure and low-temperature properties of a novel cerium stannide Ce3RuSn6

Heavy-fermion superconductivity in [formula omitted

The magnetic and transport properties of PrIr2B2 and PrIr2B2C have been investigated by dc and ac magnetic susceptibility, specific heat, electrical resistivity and magnetoresistance measurements. PrIr2B2 forms in CaRh2B2-type orthorhombic crystal structure (space group Fddd). At low fields the dc magnetic susceptibility of PrIr2B2 exhibits a sharp anomaly near 46 K which is followed by an abrupt increase below 10 K with a peak at 6 K, and split-up in ZFC and FC data below 46 K. In contrast, the specific heat exhibits only a broad Schottky type hump near 9 K which indicates that there is no long range magnetic order in this compound. The thermo-remanent magnetization is found to decay very slowly with a mean relaxation time τ = 3917 s. An ac magnetic susceptibility measurement also observes two sharp anomalies; the peak positions strongly depend on the frequency and shift towards high temperature with an increase in frequency, obeying the Vogel–Fulcher law as expected for a canonical spin-glass system. The two spin-glass transitions occur at freezing temperatures Tf1 = 36 K and Tf2 = 3.5 K with shifts in the freezing temperatures per decade of frequency δTf1 = 0.044 and δTf2 = 0.09. An analysis of the frequency dependence of the transition temperature with critical slowing down, τmax/τ0 = [(Tf−TSG)/TSG]−zν, gives τ0 = 10−7 s and exponent zν = 8, and the Vogel–Fulcher law gives an activation energy of 84 K for Tf1 and 27.5 K for Tf2. While zν = 8 is typical for spin-glass system, the characteristic relaxation time τ0 = 10−7 s is very large and comparable to that of superspin-glass systems. An addition of C in PrIr2B2 leads to PrIr2B2C which forms in LuNi2B2C-type tetragonal structure (space group I4/mmm) and remains paramagnetic down to 2 K. The specific heat data show a broad Schottky type anomaly, which could be fairly reproduced with CEF analysis which suggests that the ground state is a CEF-split singlet and the first excited state singlet is situated 15 K above the ground state. The Sommerfeld coefficient γ∼300 mJ mol−1 K−2 of PrIr2B2C is very high and reflects a heavy fermion behaviour in this compound. We believe that the heavy fermion state in PrIr2B2C has its origin in low lying crystal field excitations as has been observed in PrRh2B2C.

In this paper, we report on the discovery of a spinel compound, Co0.7Al2S4, which was synthesized at high-pressure. The systematic characterizations were carried out by structural, magnetic, and heat capacity measurements. The compound crystallizes into a cubic structure with the space group Fd3̅m (no. 227) and the lattice constant a = 9.9580(1) Å. Magnetic susceptibility measurements suggest that Co0.7Al2S4 exhibits a spin glass ground state, freezing at Tf ∼ 7.2 K with a Weiss temperature Tθ ∼ -115.9 K, which is verified by ac magnetic susceptibility and heat capacity measurements. The frustration parameter f for Co0.7Al2S4 is calculated to be about 16.6, based on the formula f = | Tθ/Tf |, indicating that Co0.7Al2S4 is a high-frustration magnet. Specific heat data displays a T2 dependence below the freezing temperature, which is different from the linear dependence observed in a common spin glass system. Compared with the similar compound CoAl2O4, it is suggested that the vacancies in the Co sites should be responsible for the occurrence of the spin glass behavior of Co0.7Al2S4.

Magnetic ordering and low-temperature thermodynamic properties of ErFe 2Ge 2

The iodate anion group has been widely used for design and synthesis of functional materials including nonlinear optical materials but rarely for magnetic materials. Particularly, none of magnetic iodate fluorides has been reported yet. In this work, first, two novel magnetic iodate fluorides MIO3F (M = Co 1 and Ni 2) have been synthesized by a hydrothermal method and characterized by magnetic susceptibility, magnetization, and heat capacity measurements as well as thermogravimetry, Fourier transform infrared spectroscopy (FT-IR), and ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy. Compounds 1 and 2 are isostructural and crystallize in the monoclinic space group P21/n with alternating M2+-F2-M2+-O2-M2+ zigzag spin chains along the b axis, which are further separated by triangular IO3 groups in the ab plane. Magnetic susceptibilities suggest that 1 exhibits an antiferromagnetic long-range order (LRO) at 16.5 K, confirmed by heat capacity results with released entropy consistent with the theoretical value for a pseudo-spin of 1/2 for Co2+ at low temperatures. Meanwhile, 2 displays a broad maximum around 10.5 K for low dimensional magnetism followed by a sharp peak at 5.7 K indicating the occurrence of an LRO transition, in good agreement with the heat capacity measurement. Field-dependent magnetizations show an obvious spin-flop transition around 4.5 T and a magnetic hysteresis loop between 4.5 and 7 T for 1, but only a slight slope change could be observed around 2.3 T for 2. Thermal stability, FT-IR, and UV-vis-NIR spectroscopy of 1 and 2 are also reported.

Synthesis and Characterization of Ni 3S 2 Single Crystals

Intermediate valence state of cerium in CeNi