Raman study of intermultiplet crystal-field excitations inNd2CuO4

Low-temperature specific heat ofNd2−xCexCuOHiền1, Duijn2, Colpa3 et al. 1998Phys. Rev. B152131View full textAdd to dashboardCite

“…Apart from CEF parameters the model contains three additional fitting parameters: one describing the Nd-Cu interaction and two, denoted by n RR dif and n RR sum , being certain linear combinations of the three Nd-Nd exchange constants we introduced for the description of the interaction between the different Nd sublattices in Nd 2 CuO 4Ϫy . By using the CEFparameter set proposed by Jandl et al, 17 we could find a single set of values for the other three fitting parameters, which could describe simultaneously all experimental curves except the one measured for 2 T applied in the ab plane.…”

“…V A. Using the CEF-parameter set of Jandl et al, 17 we found: ⌬E/B eff Nd ϭ0.026 K/T and 1.841 K/T for the effective magnetic field B eff Nd at the Nd site parallel and perpendicular to the c axis, respectively. ͑These two values turn out to be about constants at all strengths of B eff Nd in the range of interest in the present paper.͒ We note, however, that without any effective field our calculation with this CEF-parameter set gives an energy-level scheme with the five doublets: 0, 185, 352, 405, and 1121 K, for the Nd 3ϩ ion in the 4 I 9/2 lowest multiplet.…”

“…For this choice we required that the set should reproduce reasonably well the anisotropic behavior of the field effect as observed in our specific-heat measurements, i.e., ͑almost͒ no shift of the ͑maximum of the͒ specific-heat curve for fields B appl applied along the c axis, and a substantial shift for fields applied in the ab plane. We carried out the specific-heat calculations using all CEF-parameter sets published so far, [9][10][11][12][13]17 It is self-evident ͑in view of the splitting of the groundstate doublet compared to the distance of the next doublet͒ that in our calculations the maximum in the specific-heat curve is constant for all applied-field strengths as long as we ignore the Nd-Nd interaction. This maximum is about 7.5% higher than the one measured at zero applied field.…”

Infrared optical properties ofPr2CuO4

“…19 In fact, due to the sigTypeset by REVT E X nificant exchange interactions between the Pr ions which are mediated through the copper-oxygen layers, there is a Pr contribution to the susceptibility 12 below ≈ 200 K. The optical properties of Nd 2 CuO 4 have been investigated in ceramics and single crystals. 20,21,22,23,24,25,26,27 Single crystals of Pr 2 CuO 4 have been studied at either room temperature 28,29,30,31 or at low temperature 11,32 (≈ 10 K), but there has been no detailed investigation of the temperature dependence of the optical properties of this material. Furthermore, there is some disagreement in the literature with respect to the vibrational parameters of the E u modes.…”

Crystal-field excitations in the visible spectrum of Nd2CuO4

“…Electron Raman scattering and infrared (IR) absorption provided a powerful experimental tool to study the crystal-field (CF) excitations in Nd 2−x Ce x CuO 4 [1][2][3][4]. They complement inelastic neutron experiments (see ref.…”