Magnetic susceptibility and specific heat of Pr2−xCexCuO4−y
TL;DR: The site symmetry of Pr3+ in Pr2−xCexCuO4−y (PCCO) host is D4h and a crystal field Hamiltonian appropriate to tetragonal symmetry was used to analyze the magnetic susceptibility data as discussed by the authors.
Abstract: We report here the measurements of magnetic susceptibility of Pr2−xCexCuO4−y (x=0, 0.05 and 0.15) from 2K to 300K and the specific heat of Pr1.85Ce0.15CuO4 between 6K and 60K. Fitting of the magnetic susceptibility data to a Curie-Weiss law gave effective magnetic moment (peff) values close to the free ion value of 3.58μB for Pr3+. peff was found to decrease with increase in cerium concentration. The site symmetry of Pr3+ in Pr2−xCexCuO4−y (PCCO) host is D4h and a crystal field (CF) Hamiltonian appropriate to tetragonal symmetry was used to analyze the magnetic susceptibility data. J-mixing of all the thirteen multiplets of Pr3+ and intermediate coupled wave functions have been included. A best set of CF parameters obtained not only explains the magnetic susceptibility but also the inelastic neutron scattering spectra (INS) reasonably well. The Schottky component together with Debye and Einstein contributions successfully accounts for the measured specific heat.
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TL;DR: In this article, specific heat measurements in the temperature T range 0.5 K ⩽ T ⩾ 30 K were performed on insulating Ln 2 CuO 4 compounds (Ln = Pr, Nd, Sm, Eu and Gd) and on superconducting Nd 1.85 M 0.2 for both M = Ce and Th.
Abstract: Specific heat measurements in the temperature T range 0.5 K ⩽ T ⩽ 30 K were performed on insulating Ln 2 CuO 4 compounds (Ln = Pr, Nd, Sm, Eu and Gd) and on superconducting Nd 1.85 M 0.15 CuO 4 − y compounds (M = Ce and Th). The specific heat of Eu 2 CuO 4 and Pr 2 CuO 4 were analyzed to obtain electronic contributions and Debye and Einstein lattice contributions. The data for the compounds Nd 2 CuO 4 , Sm 2 CuO 4 and Gd 2 CuO 4 show magnetic ordering of the trivalent Ln ions at temperatures T M of 1.7 K, 5.94 K and 6.66 K, respectively. Magnetic ordering is also observed in Nd 1.85 M 0.15 CuO 4 − y at T M = 1.2 for both M = Ce and M = Th. The data for doped and undoped Nd 2 CuO 4 were compared to derive an electronic contribution to the specific heat of Nd 1.85 Ce 0.15 CuO 4 − y , with γ ≈ 53 mJ/mol K 2 .
47 citations
TL;DR: In this article, a single-crystal of Pr2CuO4 in the temperature range from 1.5 to 300 K was used for bulk-magnetisation measurements and neutron-scattering experiments.
Abstract: Bulk-magnetisation measurements and neutron-scattering experiments were performed both on a polycrystalline sample and on a single-crystal of Pr2CuO4 in the temperature range from 1.5 to 300 K. Pr2CuO4 crystallizes with theT′ (Nd2CuO4)-type structure. We observed antiferromagnetic ordering of the Cu moments belowT N =(190±2) K in a single crystal and belowT N =(250±10)K in powder material. The magnetic unit cell dimensions area m =2a o ,c m =c o ;the Cu moments are oriented in the basal plane with a magnetic saturation moment of μCu=(0.45±0.12)μ B . Pr3+ does not order magnetically above 1.5K due to its crystal-field induced singlet ground state as verified by inelastic neutron scattering.
38 citations
TL;DR: In this paper, the magnetic excitation spectra of Pr 2 CuO 4 and Nd 2CuO 4 determined by inelastic neutron scattering over the temperature range 15-300 K are reported.
Abstract: The magnetic excitation spectra of Pr 2 CuO 4 and Nd 2 CuO 4 determined by inelastic neutron scattering over the temperature range 15–300 K are reported. Well-defined transitions between the rare earth ion crystal field levels have been observed up to about 100 meV for both compounds. The results are analyzed in terms of a crystal field model under the scheme of intermediate coupling calculated by spherical tensor techniques. The calculated crystal field excitation spectra and magnetic susceptibilities agree well with experiments. No measurable influence of the rare earth crystal field structures by the antiferromagnetic ordering of copper spins is found in these materials.
17 citations
TL;DR: In this paper, the magnetic susceptibilities of single crystals of PrBa2Cu3O7−δ are reported, which are tetragonal with space group P4/mmm.
Abstract: The crystal structure, and magnetic susceptibilities of single crystals of PrBa2Cu3O7−δ are reported here. The crystals are tetragonal with space group P4/mmm. A crystal field (CF) Hamiltonian appropriate to tetragonal symmetry at the Pr3+ site was diagonalised considering J-mixing. A set of CF parameters is being reported which fits the susceptibility data closely and explains the reported results of inelastic neutron scattering measurements also reasonably well.
14 citations
TL;DR: In this paper, the crystal-field levels and the crystal field parameters of Pr2CuO4 were determined from the observed transitions, consistent with the large magnetic anisotropy observed in single-crystal susceptibility data.
Abstract: Neutron spectroscopy has been employed to study the crystal-field excitations in Pr2CuO4. The energetic ordering of the crystal-field levels and the crystal-field parameters are determined from the observed transitions. Our results are consistent with the large magnetic anisotropy observed in single-crystal susceptibility data.
11 citations