We report on optical measurements of the 1D Heisenberg antiferromagnet KCuF(3). The crystal-field excitations of the Cu(2+) ions have been observed and their temperature dependence can be understood in terms of magnetic and exchange-induced dipole mechanisms and vibronic interactions. Above T(N) we observe a new temperature scale T(S) characterized by the emergence of narrow absorption features that correlate with changes of the orbital ordering as observed by Paolasini et al. [Phys. Rev. Lett. 88, 106403 (2002)]. The appearance of these optical transitions provides evidence for a symmetry change above the Neel temperature that affects the orbital ordering and paves the way for the antiferromagnetic ordering.
Optical Evidence for Symmetry Changes above the Néel Temperature of KCuF3
GHIGNA, PAOLO;
2008-01-01
Abstract
We report on optical measurements of the 1D Heisenberg antiferromagnet KCuF(3). The crystal-field excitations of the Cu(2+) ions have been observed and their temperature dependence can be understood in terms of magnetic and exchange-induced dipole mechanisms and vibronic interactions. Above T(N) we observe a new temperature scale T(S) characterized by the emergence of narrow absorption features that correlate with changes of the orbital ordering as observed by Paolasini et al. [Phys. Rev. Lett. 88, 106403 (2002)]. The appearance of these optical transitions provides evidence for a symmetry change above the Neel temperature that affects the orbital ordering and paves the way for the antiferromagnetic ordering.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
