Phase transition and thermal order-by-disorder in the pyrochlore antiferromagnet Er2Ti2O7: A high-temperature series expansion study

Article

关键词: DIPOLAR INTERACTIONS;    SPIN-ICE;    ORIGIN;   

DOI  :  10.1103/PhysRevB.88.220404

来源: SCIE

【 摘 要 】

We use a high-temperature series expansion method to study the phenomenon of thermal order-by-disorder in the rare-earth pyrochlore material Er2Ti2O7 on its approach to the critical temperature T-c. We show that its anisotropic exchange parameters, {J(e)}, characterizing an effective spin-1/2 model and recently determined from high-field inelastic neutron scattering spectra, describe very well the thermodynamic properties of the material in the paramagnetic phase and near Tc. While different q = 0 XY order-parameter susceptibilities show a high degree of degeneracy, a nonlinear susceptibility, related to the sixth power of the order parameter, reveals a thermal order-by-disorder selection of the same noncollinear psi(2) state as found in Er2Ti2O7. Our results provide a rather definite quantitative demonstration that thermal order-by-disorder is operating at T-c in this frustrated quantum spin-1/2 antiferromagnetic material.

【 授权许可】

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