Speaker
Vitor Amaral
(Universidade de Aveiro, Portugal)
Description
The Pr1-xCaxMnO3 displays a variety of phase transitions associated with the spin,
lattice, charge and orbital degrees of freedom [1],[2]. PrMnO3 and CaMnO3 are
antifeerromagnetic, and low doped (x<0.32) samples are ferromagnetic below Tc~130K.
For 0.32<x<0.90 the system presents a robust Charge Order state (CO) for
temperatures below TCO~150-235 K and an antiferromagnetic insulator state below
TN~100-180 K. Detailed real-space atomic-scale information is necessary to achieve
better undertanding of such order/disorder effects.
111mCd111Cd Perturbed Angular Correlation (PAC) studies were used to infer about
atomic-scale distortions in the temperature range 10-600K encompassing the
charge,orbital and magnetic ordering transitions. The electrical-field gradient
(EFG) generated by the charge distribution around the probe shows strong anomalies
when the system undergoes the charge-order transition. In particular, the principal
component of the EFG (Vzz) presents a sharp discontinuity at the CO transition.
[1] Y. Tomioka et al. Phys. Rev. B 53, 1689 (1996)
[2] M. S. Reis et al., Phys. Rev. B 71, 144413 (2005)
Author
Vitor Amaral
(Universidade de Aveiro, Portugal)
Co-authors
Armandina Maria Lima Lopes
(Universidade de Aveiro, Portugal)
E. Rita
(ITN, Sacavém, Portugal)
J. G. Correia
(ITN, Sacavém, Portugal)
J. P. Araújo
(Universidade do Porto, Portugal)
M. S. Reis
(Universidade de Aveiro, Portugal)
P. B. Tavares
(UTAD, Vila Real, Portugal)
T. M. Mendonça
(Universidade do Porto, Portugal)
Y. Tokura
(University of Tokyo, Japan)
Y. Tomioka
(JRCAT, Tsukuba, Japan)
