Crystal field effect and geometric frustration in Er2Ti2O7 —an XY antiferromagnetic pyrochlore |
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Authors: | Papri Dasgupta Yatramohan Jana |
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Affiliation: | a Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata-700032, India b B.S. College, Tangrakhali 743329, W.B., India |
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Abstract: | Magnetic susceptibility of powder Er2Ti2O7 (ErT) is measured between 300 K and 80 K. shows a Curie-Weiss (CW) type behaviour with ErTiO3.5 and . A crystal field (CF) analysis of our experimental data, g-values (g∥=0.27 and g⊥=7.8) and the positions of two CF levels (reported earlier from an inelastic neutron scattering study) provide CF parameters and CF levels of the ground 4I15/2 and excited multiplets of ErT. The theoretical follows a CW-type behaviour, with . Single-ion magnetic anisotropy (χ⊥−χ∥) is 9500×10−6 emu/mol ErTiO3.5 at 300 K, which increases by ∼54 times at 10 K and ErT resembles an XY planar system. It can be inferred from CF analysis that the earlier observed change of from −13 K to −22 K below 50 K is not due to the CF effect. Nuclear hyperfine (HF) levels of 167ErT and 166ErT are calculated and the theoretical curve of vs. T (K) for T<TN matches the observed results. Mössbauer lines expected for 166ErT are also predicted. |
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Keywords: | 75.10.Dg 75.30.Gw 75.40.Cx 33.45.+x 77.84.Dy |
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