| Autor: |
Christovam DS; Instituto de Física 'Gleb Wataghin,' UNICAMP, Campinas-SP, 13083-970, Brazil., Freitas GS; Instituto de Física 'Gleb Wataghin,' UNICAMP, Campinas-SP, 13083-970, Brazil., Piva MM; Instituto de Física 'Gleb Wataghin,' UNICAMP, Campinas-SP, 13083-970, Brazil.; Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany., Souza JC; Instituto de Física 'Gleb Wataghin,' UNICAMP, Campinas-SP, 13083-970, Brazil., Malcolms MO; Instituto de Física 'Gleb Wataghin,' UNICAMP, Campinas-SP, 13083-970, Brazil., Canton OL; Instituto de Física Teórica, Universidade Estadual Paulista-UNESP, São Paulo-SP, 01140-070, Brazil., Leão JB; NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA., Ratcliff W; NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA., Lynn JW; NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA., Adriano C; Instituto de Física 'Gleb Wataghin,' UNICAMP, Campinas-SP, 13083-970, Brazil., Pagliuso PG; Instituto de Física 'Gleb Wataghin,' UNICAMP, Campinas-SP, 13083-970, Brazil. |
| Abstrakt: |
We report the evolution of the magnetic properties of C e 2 R h 1 - x I r x I n 8 - y C d y single crystals. In particular, for C e 2 R h 0.5 I r 0.5 I n 8 ( T N = 2.0 K ) and C e 2 R h 0.5 I r 0.5 I n 7.79 C d 0.21 ( T N = 4.2 K ), we have solved the magnetic structure of these compounds using single-crystal neutron magnetic diffraction experiments. Taking the magnetic structure of the C e 2 R h I n 8 heavy-fermion antiferromagnet as a reference, we have identified no changes in the q = 1 2 , 1 2 , 0 magnetic wave vector; however, the direction of the ordered Ce 3+ moments rotates toward the a b plane, under the influence of both dopants. By constraining the analysis of the crystalline electric field (CEF) with the experimental ordered moment's direction and high-temperature magnetic-susceptibility data, we have used a mean-field model with tetragonal CEF and exchange interactions to gain insight into the CEF scheme and anisotropy of the CEF ground-state wave function when Cd and Ir are introduced into C e 2 R h I n 8 . Consistent with previous work, we find that Cd doping in C e 2 R h I n 8 tends to rotate the magnetic moment toward the a b plane and lower the energy of the CEF excited states' levels. Interestingly, the presence of Ir also rotates the magnetic moment towards the a b plane although its connection to the CEF overall splitting evolution for the y = 0 samples may not be straightforward. These findings may shed light on the origin of the disordered spin-glass phase on the Ir-rich side of the phase diagram and also indicate that the C e 2 M I n 8 compounds may not follow exactly the same Rh-Ir CEF effects trend established for the C e 2 M I n 5 compounds. |
