Critical phenomena and femtosecond ordering dynamics associated with electronic and spin-ordered phases inYVO3andGdVO3

Abstract

Critical phenomena and femtosecond ordering dynamics associated with electronic and spinordered phases in YVO3 and GdVO3 Yusupov, R. V.; Mihailovic, D.; Colin, C. V.; Blake, G. R.; Palstra, T. T. M. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. We present a systematic study of the electronic-and spin-excitation dynamics associated with the sequence of spin-and orbital-ordering phase transformations in the complex vanadates YVO 3 and GdVO 3 with ultrafast optical pump-probe reflectance spectroscopy. Relaxation dynamics occurs on a different time scale for each of the ordering transitions, which enables us to unambiguously associate the critical behavior in the dynamics with the observed ordering phenomena. Spin-ordering dynamics is observed on two time scales: r Ӎ 2 ps ͑rise time͒ and s Ӎ 300-3000 ps ͑decay time͒, observed below T N in both compounds. In contrast, the relaxation dynamics associated with orbital ordering occurs in YVO 3 on a time scale of o Ӎ 20-50 ps. From the temperature dependence of the dynamics, we observe that in both the G-type and C-type orbitally ordered ͑OO͒ phases of YVO 3 spin order develops in a second-order mean-field fashion with the Nèel temperature of the C-OO phase found from our data T N C =83Ϯ 7 K. In GdVO 3 we identify the emergence of a new ordered phase within the phase-separated state below 60 K. A new response component with a lifetime of ϳ60 ps is observed below 60 K together with other anomalies in the ⌬R / R͑⌬t͒ data. This new phase is not resolved in x-ray diffraction and is not present in YVO 3 .

Ultrafast optical spectroscopy of the lowest energy excitations in the Mott insulator compound YVO3: Evidence for Hubbard-type excitons

“…A fully thermalized state is achieved only on much longer time scales (>1 ns) through spin-lattice coupling. 49 In conclusion, here we have revealed the nature of the two lowest energy peaks detected in the 1-to 3-eV optical spectra of the orbitally ordered Mott insulator YVO 3 . This finding was made possible by out-of-equilibrium experiments.…”

“…On the contrary, the low-temperature phases are characterized by a more composite optical response with fast and slow components, confirming previously reported single-color measurements. 48,49 The time-domain reflectivity measurements in the G-OO phase (116 K < T < 200 K) are characterized by a slow negative response centered at 1.94 eV [ Fig. 2(b)], which becomes more pronounced as the temperature is lowered [ Fig.…”

Resonant x-ray scattering from the4pquadrupole moment inYVO3

“…Simultaneous to the reduction in the Jahn-Teller distortion is the disorder of the orbital order. 36 This, however, is predominantly confined to the 3d electronic states, with very little overlap between the 3d and 4p electron bands. The dipole 1s-4p transition excited through the resonant scattering process at the vanadium absorption edge is, however, not sensitive to the 3d bands.…”

Modeling of complex oxide materials from the first principles: systematic applications to vanadates RVO3 with distorted perovskite structure

“…The relative role of these two mechanisms will be clarified in the next section. The quasidegeneracy of magnetic states in the monoclinic phase of GdVO 3 may be also resolved through the additional symmetry-breaking transition and emergence of a new ordered phase, as suggested in some experimental reports [27].…”