Crystal Electric Field Excitations Research Articles

Neutron spectroscopy of R 2Zn 17 compounds

In order to obtain some fundamental insight into the crystal electric field (CEF) level scheme in R 2Zn 17, neutron scattering experiments have been done on polycrystalline samples R-Pr Tb, Dy, Ho, Er and Y on the temperature range 3–100 K. Distinct CEF excitations have been observed. In order to obtain the transition energies and their probability a systematic analysis has been performed fitting the experimental results by a least-squares Gaussian process. A preliminary analysis has been made for Er compound using the CEF formalism.

Crystal electric field excitations in REBa 2Cu 3O 7−x compounds

By inelastic neutron scattering (INS) experiments we have examined crystal field excitations (CEF) in RE Ba 2Cu 3O 7−x (RE=Pr, Nd, Tm, Tb). The investigations are complemented by measurements of the specific heat.

Separation of crystal-field levels and phonons in Pr dideuteride using polarized neutrons

Polarized neutrons with polarization analysis are used for the first time successfully for distinguishing crystal-electric-field (CEF) excitations from phonons by investigating both the spin-flip and non-spin-flip cross sections. From this, it is shown that the 20 meV peak in Pr dideuteride, observed previously with unpolarized neutrons, arises from CEF excitations. Since this energy is nearly half the value of the CEF level at 41 meV known before, the 20 meV peak is composed of two contributions. At low temperatures it only arises from transitions from the ground state into the 20 meV level. At room temperature, on the other hand, the 20 meV level is thermally populated, so that transitions from the 20 meV into the 41 meV level are also obtained. This leads to the unexpected increase of the intensity of the 20 meV peak at increasing temperatures observed previously. The present result gives a strong contribution to the knowledge of the CEF parameters of the Pr3+ ions in PrD2.

Phonon softening in CeAl2

Neutron scattering experiments reveal an exceptionally large temperature dependence of specific phonon branches in CeAl2. In particular, this behaviour is observed in the lowest optic branches starting from the Gamma '25 phonon and in the TA (100) branch. There is strong evidence that these effects are caused by the interaction between optic phonons and the crystal electric field excitation Gamma 7 to Gamma 8.

Theory of magnetic susceptibility of mixed-valent Ce0.76La0.14Th0.1

The authors derive an expression for the magnetic susceptibility ( chi ) of a mixed-valent system in which there is a continuous valence transition to a nearly integral valent phase, taking into account the crystal electric field (CEF) splitting of the localised levels. As an example, they calculate chi of Ce0.76La0.14Th0.1 in which CEF excitations have been observed for the first time in a mixed-valent system. There is a good agreement with experimental results.