Specific heat and magnetic properties of Ce(Ru1−xPdx)2Si2 (original) (raw)
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
We have determined the ground-state wave functions and crystal-field-level schemes of CeRh 2 Si 2 and CeRu 2 Si 2 using linear polarized soft x-ray-absorption spectroscopy (XAS) and inelastic neutron scattering. We find large crystal-field splittings and ground-state wave functions which are made of mainly J z = |±5/2 with some amount of |∓3/2 in both the compounds. The 4f 0 contribution to the ground state of several members of the CeM 2 Si 2 family with M = (Cu, Ru, Rh, Pd, and Au) has been determined with XAS, and the comparison reveals a trend concerning the delocalization of the f electrons. Absolute numbers are extracted from scaling to results from hard x-ray photoelectron spectroscopy on CeRu 2 Si 2 by Yano et al.
Magnetic instabilities in CeRu2Si2 compounds
Physica B: Condensed Matter, 1999
Neutron scattering experiments were recently performed in compounds of the CeRu Si family. The topic addressed is the proximity of magnetic instabilities. The first one is the proximity of a ¹"0 K quantum phase transition experimentally achieved with lanthanum doping. The second kind of instability is linked to the competition between antiferromagnetic and ferromagnetic interactions in these materials. The pseudo-metamagnetic transition of CeRu Si and the occurrence of an antiferromagnetic phase in the ferromagnetic compound CeRu Ge were studied. Comparisons with macroscopic measurements are made using a simple analysis of the data.
Low-temperature properties of the heavy-fermion compound CeRu2Si2 at the metamagnetic transition
Journal of Low Temperature Physics, 1990
Magnetization measurements performed below 1 K on a single-crystalline sample of the heavy fermion compound CeRueSi2 are reported. The field variation of the linear term of the specific heat y derived from these data (via a Maxwell relation) exhibits a large peak at the metamagnetic-like transition at B* (=Z 7 at T ~ 0). Thermal-expansion measurements, show a drastic drop of the temperature where a Fermi liquid behavior is reached when B-> B'~. Similar experiments performed on a single-crystalline Ceo.95Lao.osRu2Si2 sample show a broadening of all the anomalies at B* and a reduction of their intensities. These results strongly suggest that pure CeRu2Si2 approaches a magnetic instability at B'for T ~O.
Experimental study of physical properties in the complex magnetic phase diagram of Ce(Rh1-xRux)3B2
Physical Review B, 2001
We have investigated the electronic structure and magnetic properties of the new ternary Ce 1Ϫx La x RhSn system. The 3d and 4d x-ray photoelectron spectroscopy ͑XPS͒ spectra indicate a mixed valence of Ce. Analysis of the 3d 9 4 f 2 weight in the 3d XPS spectra using Gunnarsson-Schönhammer theory suggests a hybridization interaction ⌬ of about 120 meV for different compositions x of the system. The magnetic measurements indicate the existence of a highly anomalous weak ferromagnetic state below ϳ220 K in Ce 1Ϫx La x RhSn for xϽ0.6. This ferromagnetism could originate from the ordering of Ce local moments due to strong Ce 4 f conduction electron hybridization via the Ruderman-Kittel-Kasuya-Yosida ͑RKKY͒ interaction. The (T) and (T) data are consistent with non-Fermi liquid behavior for xр0.5, while the magnetic behavior in the range xϾ0.5 is dominated by spin fluctuations.
Magnetic and Thermodynamic Properties of Ce 4 RuAl
Acta Physica Polonica A, 2015
The results of magnetic susceptibility and heat capacity measurements are reported for the Ce4RuAl compound above room temperature to low temperature range (400 K to 0.34 K) and in the magnetic eld up to 7 T. The magnetic susceptibility χ(T ) exhibits a distinct anomaly at 0.95 K which most probably suggests a paramagnetic to antiferromagnetic phase transition. The magnetic susceptibility obeys the CurieWeiss law in the region 100400 K and revealed an eective magnetic moment µ eff = 2.18 µB/Ce which is less than the value for free Ce 3+ (µ eff = 2.54 µB). The paramagnetic Weiss temperature indicates net antiferromagnetic correlations. In the specic heat a peak at 1.3 K supports the bulk nature of the phase transition observed in χ(T ). The Sommereld coecient is moderately enhanced in the paramagnetic phase, and suggests fc correlations among the electrons prior to magnetic ordering. The obtained Sommereld coecient γ behavior is consistent with the Anderson model-based theoretical predictions.