Low-energy excitations in the magneto-optical response of αNaV2O5

A. B. Sushkov, J. L. Musfeldt, X. Wei, S. A. Crooker, J. Jegoudez, and A. Revcolevschi
Phys. Rev. B 66, 054439 – Published 29 August 2002
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Abstract

We employ the sensitivity of high-energy sidebands on the 1 eV absorption band to temperature and applied magnetic field to investigate the phase transition in αNaV2O5. Data were collected in steady (45 T) and pulsed (60 T) fields between 4 and 45 K. We use the spectral changes to map the HT phase diagram and find a temperature-independent phase boundary at 27T (Hc) which persists above 34 K [Tc(0)], a kink in Tc(H) near 27 T, and H2 behavior of Tc(H) in the high-field phase with prefactor α=0.09. It is notable that the energy scale of Hc is identical to that of Tc(0). To understand the high-energy sidebands on the 1 eV band in the optical conductivity, we invoke the idea of low-energy excitations coupled with the optically induced charge transfer excitation. The 34 K phase transition is assigned as a crossover between thermal excitation over the on-rung potential barrier above Tc and tunneling through the barrier below Tc, and Hc is associated with a change in the on-rung potential, which modifies the low-energy excitation dynamics and may lead to the formation of field-induced ferromagnetic domains above 27 T.

  • Received 13 March 2002

DOI:https://doi.org/10.1103/PhysRevB.66.054439

©2002 American Physical Society

Authors & Affiliations

A. B. Sushkov and J. L. Musfeldt

  • Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996

X. Wei

  • National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310

S. A. Crooker

  • National High Magnetic Field Laboratory, MS E536, Los Alamos, New Mexico 87545

J. Jegoudez and A. Revcolevschi

  • Laboratoire de Physico-Chimie de l’Etat Solide, Université de Paris-Sud, F-91405 Orsay, France

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Vol. 66, Iss. 5 — 1 August 2002

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