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Lattice, Spin, and Electronic Anisotropies in DyFe1-x MnxO3 Perovskites
Dissertation

Lattice, Spin, and Electronic Anisotropies in DyFe1-x MnxO3 Perovskites

Chiang, Fu-Kuo
Doctor of Philosophy (PHD), 國立清華大學, 工程與系統科學系
2010

Abstract

鈣鈦礦 錳化物 鐵化物 電子自旋 電子能譜損失 Perovskite DyFeMnO3 strongly correlated structure spin EELS
The structural, magnetic properties and electronic structures of the rare-earth perovskites, DyFe1-xMnxO3 (space group, orthorhombic Pbnm), were studied, and the magnetic phase diagram of the solid solution was investigated, which unveiled an unexplored hidden field-induced weak ferromagnetism (antiferromagnetically ordered along b-axis and canted along c-axis) in the material system for x = 0.5~0.9. In the solid solution, the Jahn-Teller distortion contributed by Mn3+ gives rise to the predominance of the bc-plane sublattice with increasing Mn and also the effective onset of orbital ordering in ab-plane for x = 0.5 and above. These distinct features in the respective lattice and orbital degrees of freedom induce the Dy-(Fe,Mn) electronic interaction anisotropy primarily in bc-plane and the growing in(ab)-plane electronic anisotropy, which were simultaneously endorsed by the electronic structures, also effectively competing to each other above x = 0.5. The aroused competition of intrinsic ground states and close entanglement of those anisotropies introduced by the various lattice, orbital, and correlated electronic characters results in considerable spin frustration and eventually the favoring of the Dzyaloshinskii-Moriya interaction dictating along a-axis, in contrast to the conventionally observed b-axis and accounting for the hidden field-induced canted magnetic ordering in bc-plane. The complex interplays of these multiple factors are discussed in the work and satisfactorily explain the rich magnetic phase diagram of the solid solution, which was not investigated in details before.

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