Spin waves and quantum criticality in the frustrated XY pyrochlore antiferromagnet Er2Ti2O7


Ruff J. P. C. , Clancy J. P. , Bourque A., White M. A. , Ramazanoglu M. K. , GARDNER J. S. , ...More

PHYSICAL REVIEW LETTERS, vol.101, no.14, 2008 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 101 Issue: 14
  • Publication Date: 2008
  • Doi Number: 10.1103/physrevlett.101.147205
  • Title of Journal : PHYSICAL REVIEW LETTERS

Abstract

We report detailed measurements of the low temperature magnetic phase diagram of Er2Ti2O7. Heat capacity and time- of- flight neutron scattering studies of single crystals reveal unconventional low- energy states. Er3+ magnetic ions reside on a pyrochlore lattice in Er2Ti2O7, where local XY anisotropy and antiferromagnetic interactions give rise to a unique frustrated system. In zero field, the ground state exhibits coexisting short and long- range order, accompanied by soft collective spin excitations previously believed to be absent. The application of finite magnetic fields tunes the ground state continuously through a landscape of noncollinear phases, divided by a zero temperature phase transition at mu(0)Hc similar to 1.5 T. The characteristic energy scale for spin fluctuations is seen to vanish at the critical point, as expected for a second order quantum phase transition driven by quantum fluctuations.