Specific heat and magnetic properties of Ce(Ru1−xPdx)2Si2 (original) (raw)
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Spin dynamics of CeX2Si2(X=Au, Pd, Rh, Ru)
Physical Review B, 1989
The results of high-resolution inelastic neutron scattering experiments on CeX2Si2 (X=Au, Pd, Rb, and Ru) in the temperature interval 1.5-250 K are reported, and the interplay of 4f conduction-electron scattering and magnetic order is discussed. The quasielastic linewidths increase within the series I /2(Au) & I /2(Pd) & I /2(Rh) & I /2(Ru), although the Neel temperature of CeRh2Si2 is about four times larger than in the Auand Pd-based compounds. The quasielastic linewidth of the nonordering compound CeRu2Si2 decreases linearly with temperature and converts into an inelastic line when the thermal energy becomes smaller than I /2. An analytic function given by Kuramoto and Muller-Hartmann is applied to fit the low-temperature data of CeRu2Si2. In addition, the low-temperature inelastic line in CeRu2Si2 exhibits a strong~Q~dependence: its inelastic position and linewidth vary with~Q~.
Magnetic Phase Transition in CePd_{2}P_{2}
Acta Physica Polonica Series a
We report physical properties of CePd 2 P 2 crystallizing in the tetragonal ThCr 2 Si 2 -type structure (space group I4/mmm). Dc-magnetic susceptibility, magnetization, specific heat, electrical resistivity and magnetoresistance measurements establish a ferromagnetic ordering below the Curie temperature T C = 28.4 ± 0.2 K. Critical analysis of isothermal and isofield magnetization yields critical exponents of β = 0.405 ± 0.005, γ = 1.11 ± 0.05 and δ = 3.74 ± 0.04. The ordered state is characterized by saturation moment M s ∼ 0.98μ B and magnon energy gap Δ/k B ∼ 25-35 K. The studied properties reflect a competing influence of the Kondo and crystalline electric field (CEF) interactions. The strength of the Kondo effect is assigned by a lowtemperature Kondo scale T K ∼ 19 ± 10 K and a high-temperature Kondo scale T K H 117 ± 10 K. A model of the inelastic scattering of the conduction electrons with an exchanged CEF energy Δ CEF was applied to the magnetic resistivity. An average value Δ CEF = 260 ± 30 K is consistent in the relationships with T K and T K H . We argue that the CePd 2 P 2 compound appears to be a new ferromagnetic Kondo-lattice among the Ce-based intermetallics.
The low-temperature magnetism of cerium atoms in CeMn2Si2 and CeMn2Ge2 compounds
Journal of Physics: …, 2004
The low-temperature magnetic properties of the Ce atoms in the intermetallic compounds CeMn 2 Ge 2 and CeMn 2 Si 2 were studied. Previous neutron scattering measurements did not detect an ordered moment at Ce atoms in either compound despite the fact that they are surrounded by the Mn moments ordered ferromagnetically in the CeMn 2 Ge 2 and antiferromagnetically in the CeMn 2 Si 2 . Contrasting with this result, a recent measurement performed with the time differential perturbed angular correlation (TDPAC) technique showed the presence of a pronounced magnetic hyperfine field (MHF) at Ce sites in the CeMn 2 Ge 2 compound and no MHF in CeMn 2 Si 2 . The absence of the Ce magnetic moment and MHF in the silicide can be understood in terms of too weak a Ce-Ce magnetic interaction while in the germanide the TDPAC result suggests that some magnetic ordering of Ce atoms may occur. Aiming to understand the effects which result in the quenching of the Ce 4f moment in both cases, we performed first-principles band-structure calculations for both systems, using the full potential linear augmented plane wave method. It is shown that the magnetism of the Ce sublattice has fundamentally different nature in CeMn 2 Si 2 and CeMn 2 Ge 2 . While the Ce atoms are intrinsically nonmagnetic in the silicide, having a zero magnetic moment with both spin and orbital contributions identically zero, they display magnetic properties in the CeMn 2 Ge 2 since their very small total moment is composed of finite spin and orbital components which almost cancel each other accidentally.
Multiple magnetic phase transitions in CePd2In4
Journal of Alloys and Compounds, 2013
Low-temperature physical properties of a novel compound CePd 2 In 4 that crystallizes with its own crystal structure type (space group Pmc2 1 , Z = 10) were investigated by means of magnetic susceptibility, magnetization, heat capacity, electrical resistivity and magnetoresistivity measurements. The compound orders antiferromagnetically at T N = 2.4 K due to magnetic moments carried by fairly stable Ce 3+ ions. In the ordered state, at T t = 1.1 K, another magnetic phase transition is observed that probably signals a change in the antiferromagnetic arrangement of the Ce magnetic moments. The magnetic structures of CePd 2 In 4 appear quite sensitive to external magnetic field, which easily induces metamagnetic-like transitions in the system. The low-temperature thermodynamic and electrical transport data of CePd 2 In 4 reveal its dense Kondo nature with the characteristic energy scale fairly close to T N .
Magnetic susceptibility of CeRu3Si2 and a scaling effect in mixed-valence compounds
Physica B: Condensed Matter, 2003
To investigate the mixed-valence (MV) state in CeRu 3 Si 2 , we measured the magnetic susceptibility wðTÞ in the temperature range 8-300 K. The magnetic susceptibility is constant below 100 K, and slightly increases with increasing temperature. We estimated the spin fluctuation temperature T sf by plotting wðTÞT=C against T; where C is the Curie constant of a Ce 3+ ion. CeRu 3 Si 2 is found to be a typical MV system, indicating that wðTÞT=C is a function of T=T sf : This scaling relation is applied to the other MV compounds such as CeSn 3 .
Physical Review B, 2012
Temperature and pressure dependences of the electronic structure of the heavy-fermion system CePd 2 Si 2 have been investigated using partial fluorescence yield x-ray absorption spectroscopy and resonant x-ray emission spectroscopy at the Ce L 3 edge. The temperature dependence has also been measured for CeRh 2 Si 2 for comparison. In both compounds Ce is in a weakly mixed valence state at ambient pressure, mostly f 1 with a small contribution from the f 0 component. No temperature dependence of the Ce valence is observed at temperatures as low as 8 K. In CePd 2 Si 2 at 19 K, however, the Ce valence shows a continuous increase with pressure, indicating pressure-induced delocalization of the 4f states. Theoretical calculations based on the single impurity Anderson model reproduce the experimental results well. Pressure dependence of the difference between the ground state valence and the measured valence including the final state effect is also discussed.
Cerium moment collapse in ternary silicidesCePd2−xMnxSi2(0≤x≤2)
Physical review, 1994
Cerium I. 3 XANES (x-ray-absorption near-edge-structure) spectra were analyzed to separate Ce moment contributions and mixed valence (MV) in complex magnetic silicides CePd2 Mn"Si2 (0 x 2). The Ce valence mixing does not vary linearly with x, but increases rapidly for x 1.5. The associated moment collapse correlates with pronounced deviations of the unit-cell volume from Vegard law and the onset of structural instability. Reorientation of [001] Mn 3d antiferromagnetic order for x & 2 appears to rapidly suppress the weak Ce valence mixing coexisting with antiferromagnetic order in CeMn2Si2.
Low-temperature properties of Ce(Ru1−xMx)2Ge2, M Fe, Au
Physica B: Condensed Matter, 1995
We have performed measurements of electrical resistivity, AC susceptibility, magnetization, M6ssbauer effect and NMR on the series of intermetallic compounds Ce(Rul -xMx)2Ge2, M = Fe, Au for 0 ~< x ~< 0.1. The parent compound CeRu2Ge2 orders ferromagnetically below 7.5 K, with f-electrons showing only a small mass-enhancement at low temperatures. However, its crystal structure and Fermi surface are closely related to the heavy-electron superconductor CeRu2Si2. Analysis of X-ray diffraction patterns confirmed the structure to be of the ThCr2Si2-type, with no foreign phases detected. The results of our M6ssbauer studies indicate that Fe goes into the Ru sites with no magnetic moment. NMR signals were observed in the Fe-doped samples with quadrupolar interaction that can be related to 73Ge nucleus (I = 9/2).
Anomalous low temperature states in CeNi2Ge2and CePd2Si2
Journal of Physics: Condensed Matter, 2000
High purity samples of the paramagnetic 4f-electron metal CeNi 2 Ge 2 exhibit a non-Fermi-liquid form of the resistivity ρ ∼ T x with x < 1.5 and decreasing towards 1 with increasing sample purity. Measurements of ρ versus T as a function of magnetic field and pressure show that this strange metallic phase is connected to the proximity of an antiferromagnetic quantum critical point as in the isoelectronic relative CePd 2 Si 2 near 2.8 GPa. The anomalous power-law dependence is surprisingly stable over extended ranges in temperature and pressure and challenges current theory of magnetic quantum phase transitions.