Gapless Quantum Excitations from an Icelike Splayed Ferromagnetic Ground State in Stoichiometric Yb2Ti2O7

Published

February 3, 2016

Author(s)

J. Gaudet, K. A. Ross, E. Kermarrec, Nicholas Butch, G. Ehlers, H. A. Dabkowska, B. D. Gaulin

Abstract

The ground state of the quantum spin ice candidate magnet Yb₂Ti₂O₇ is known to be sensitive to weak disorder at the 1% level which occurs in single crystals growth from the melt. Powders grown from solid state solutions tend to be stoichiometric and display large and sharp heat capacity anomalies at relatively high temperature, T^c^0.26 K. We have carried out neutron elastic and inelastic measurements on well characterized and equilibrated stoichiometric powder samples of Yb₂Ti₂O₇ which show resolution-limited Bragg peaks to appear at low temperatures, but whose onset correlates with temperatures much higher than T_C. The corresponding magnetic structure be gapless on an energy scale < 0.09 meV at all temperatures, and organized into a continuum of scattering with vestiges of highly overdamped ferromagnetic spin waves present. These excitations differ greatly from conventional spin waves predicted for Yb₂Ti₂O₇'s mean field ordered state, but appear robust to weak disorder as they are largely consistent with those displayed by nonstoichiometric crushed single crystals and single crystals, as well as by powder samples of Yb₂Ti₂O₇'s sister quantum magnet Yb₂Sn₂O₇.

Citation

Physical Review B

Volume

93

Issue

6

Pub Type

Journals

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Citation

Gaudet, J. , Ross, K. , Kermarrec, E. , Butch, N. , Ehlers, G. , Dabkowska, H. and Gaulin, B. (2016), Gapless Quantum Excitations from an Icelike Splayed Ferromagnetic Ground State in Stoichiometric Yb₂Ti₂O₇, Physical Review B, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=920059 (Accessed April 25, 2024)