Magnetic Properties of Tb2Ir2O7

  • 簡 冠程

Student thesis: Master's Thesis


In recent years iridated-pyrochlore compounds with 5d-electron elements have attracted a lot of interest primarily because of the electron-electron correlations and spin-orbit interactions in these materials We have prepared polycrystalline samples of pyrochlore Tb2Ir2O7 using conventional solid state reaction and we will present results from XRD resistivity magnetization specific heat ?SR and neutron scattering experiments Three anomalies at T ~ 132 K 50 K and 6 K have been observed in our DC magnetization measurements Our magnetization and resistivity measurements on Tb2Ir2O7 confirm that Ir4+ ions are ordered and undergo a metal-insulator transition (MIT) at TMI ~132 K The muon spin relaxation (μSR) results reveal internal static field below the metal-insulator transition temperature (TMI) and three anomalies in the μSR oscillation frequencies observed near 130 K 50 K and 6 K are consistent with the results of DC magnetization The magnetic structure of Tb2Ir2O7 below 50 K is an antiferromagnetic "all-in-all-out" (AIAO) state The new observed sharp peak revealed at ~0 1 K in specific heat is in line with the form of the Schottky specific heat of the Tb3+ nuclear hyperfine The time-of-flight inelastic neutron scattering results and spin wave calculation confirm the integrated magnetic entropy approaches to the value of Rln4 indicating a doublet-doublet scheme for Tb3+ in the system We propose the spin wave excitation model from a candidate exchange interactions we found the strong nearest-neighbor antiferromagnetism AIAO ordered by Tb3+ sublattice
Date of Award2018 Feb 1
Original languageEnglish
SupervisorLieh-Jeng Chang (Supervisor)

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