Resolving the spin reorientation and crystal-field transitions in TmFeO3 with terahertz transient.

Kailin Zhang,Shixun Cao,Guohong Ma,Bo Li,Zeyu Zhang,Zuanming Jin,Xian Lin,Kai Xu,Xiumei Liu

doi:10.1038/srep23648

Kailin Zhang, Shixun Cao + Show 7 more

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https://doi.org/10.1038/srep23648

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Abstract

Rare earth orthoferrites (RFeO3) exhibit abundant physical properties such as, weak macroscopic magnetization, spin reorientation transition, and magneto-optical effect, especially the terahertz magnetic response, have received lots of attention in recent years. In this work, quasi-ferromagnetic (FM) and quasi-antiferromagnetic (AFM) modes arising from Fe sublattice of TmFeO3 single crystal are characterized in a temperature range from 40 to 300 K, by using terahertz time-domain spectroscopy (THz-TDS). The magnetic anisotropy constants in ac-plane are estimated according to the temperature-dependent resonant frequencies of both FM and AFM modes. Here, we further observe the broad-band absorptions centered ~0.52, ~0.61, and ~1.15 THz below 110 K, which are reasonably assigned to a series of crystal-field transitions (R modes) of ground multiplets (6H3) of Tm3+ ions. Specially, our finding reveals that the spin reorientation transition at a temperature interval from 93 to 85 K is driven by magnetic anisotropy, however, which plays negligible role on the electronic transitions of Tm ions in the absence of applied magnetic fields.

Highlights

Rare earth orthoferrites (RFeO3) exhibit abundant physical properties such as, weak macroscopic magnetization, spin reorientation transition, and magneto-optical effect, especially the terahertz magnetic response, have received lots of attention in recent years
We investigate the magnetic excitation of Fe ions as well as the electronic excitations of Tm ions in TmFeO3, in a broad temperature range from 40 to 300 K, by using terahertz time-domain spectroscopy (THz-TDS)
In the temperature range of spin-reorientation transition (SRT), the macroscopic magnetization rotates continuously from c(a) towards a(c) axis, and the amplitudes of both AFM and FM modes are expected to change with temperature, due to the cross production between vectors M and HTHz

Summary

Introduction

Rare earth orthoferrites (RFeO3) exhibit abundant physical properties such as, weak macroscopic magnetization, spin reorientation transition, and magneto-optical effect, especially the terahertz magnetic response, have received lots of attention in recent years. Quasi-ferromagnetic (FM) and quasi-antiferromagnetic (AFM) modes arising from Fe sublattice of TmFeO3 single crystal are characterized in a temperature range from 40 to 300 K, by using terahertz time-domain spectroscopy (THz-TDS). The temperature-dependent magnetocrystalline anisotropy is the dominating mechanism for thermal-induced spin-reorientation transition (SRT), a rotation of the macroscopic magnetization by 90 degree, in RFeO3. Such a spin reorientation is thought to arise from temperature-induced repopulation of 4f-electrons in the rare-earth ions, which leads to a renormalization of the R-Fe interaction[1]. The resonant frequencies of FM (square symbols) and AFM (circular symbols) modes are shown as functions of temperature

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