Abstrakt
CeCuAl3 and CeAuAl3, crystallizing in the non-centrosymmetric BaNiSn3 tetragonal structure, are known mainly for their unusual neutron scattering spectra involving additional excitations ascribed to vibron quasi-bound quantum state in CeCuAl3 and anti-crossing of phonon and crystal field excitations in CeCuAl3. In this work, we present results of nuclear magnetic resonance (NMR) experiments on their lanthanum analogues-LaCuAl3 and LaAuAl3.
The character of NMR spectra of La-139, Al-27, and Cu-65 measured in LaAuAl3 and LaCuAl3 is dominated by electric quadrupole interaction. The spectral parameters acquired from experimental data are confronted with values obtained from the electronic structure calculations.
The results show remarkable differences for the two compounds. The La-139 spectrum in LaAuAl3 can be interpreted by a single spectral component corresponding to uniform environment of La atoms in the crystal structure, whereas for LaCuAl3 the spectrum decomposition yields a wide distribution of spectral parameters, which is not possible to explain by a single La environment, and multiple non-equivalent La positions in the crystal structure are required to interpret the spectrum.