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梶田 遥一*; 山岸 茂直*; 林田 健志*; 木村 健太*; 萩原 雅人; 木村 剛*
no journal, ,
Ferroaxial order is characterized by the symmetry breaking of the mirror parallel to the principal axis in the crystal structure. It is predicted to show unique physical properties such as the antisymmetric thermopolarization, that is, the induced-polarization perpendicular to the applied temperature gradient [1]. So far, materials showing ferroaxial order are limited. A recent study focused on the glaserite-type compounds belonging to the space group P-3 (No. 147) or P-3m1 (No. 164) as ferroaxial material candidates and experimentally confirmed that one of such compounds, KZr(PO) is a ferroaxial material [2]. In this work, we focus on one of the glaserite-type compounds, NaBaCo(PO). We synthesized polycrystalline samples by a solid-state reaction and single crystals by a flux method similar to the previous report [3]. We conducted measurements of thermogravimetry and differential thermal analysis (TG-DTA) for these samples and found the possibility that NaBaCo(PO) undergoes a phase transition at around 700 K. Through neutron powder diffraction measurements, we revealed that the phase transition is a ferroaxial transition from ferroaxial P-3; to nonferroaxial P-3m1. In the ferroaxial phase of NaBaCo(PO), there are two domain states depending on the sign of the order parameter, which corresponds to the rotational direction of the PO tetrahedron. Such domain states can be visible with the electrogyration, that is, the gyration induced by an applied electric field [4]. Using this technique, we attempted to visualize the ferroaxial domains in NaBaCo(PO). In this presentation, details of the experiments and results will be presented. [1] J. Nasu and S. Hayami, Phys. Rev. B 105, 245125 (2022).[2] S. Yamagishi et al., Chem. Mater. 35, 747 (2023).[3] R. Zhong et al., Proc. Natl. Acad. Sci. USA 116, 14505 (2019).[4] T. Hayashida et al., Nat. Commun. 11, 4582 (2020).
山岸 茂直*; 林田 健志*; 三澤 竜介*; 木村 健太*; 萩原 雅人; 村田 智城*; 廣瀬 左京*; 木村 剛*
no journal, ,
In recent years, ferroaxial order is discussed as a new class of ferroic states [1,2]. This order is a structural order characterized by a partial rotational distortion, which was initially introduced by R.D. Johnson et al. in 2011 [1]. It has been attracting increased interests because of its potential for unconventional physical phenomena and new functionalities such as transverse responses in which input external fields induce output conjugate physical quantities along the perpendicular direction [3]. However, only a few ferroaxial materials have been reported to date, (e.g., NiTiO [4,5] and RbFe(MoO) [5]). In this work, we sought new ferroaxial materials by formula-based screening using a regular expression search and the symmetry detection algorithm. As a result, we found that a glaserite- type compound, KZr(PO) , is one of the promising candidates for ferroaxial materials. Furtheremore, our ab initio phonon calculations suggested that this compound undergoes a ferroaxial transition. Experimentally, by the structural analysis using neutron powder diffraction measurements, we demonstrated that KZr(PO) shows a ferroaxial transition at about 700 K. The ferroaxial nature of KZr(PO) was further confirmed by the observation of its domain structures using a linear electrogyration effect, that is, optical rotation in proportion to an applied electric field [6]. In this presentation, we will provide details of the database screening and the experiments. [1] R. D. Johnson et al., Phys. Rev. Lett. 107, 137205 (2011). [2] J. Hlinka et al., Phys. Rev. Lett. 116, 17 (2016). [3] S.-W. Cheong et al., npj Quantum Mater. 6, 58 (2021). [4] T. Hayashida et al., Nat. Commun. 11, 4582 (2020). [5] T. Hayashida et al., Phys. Rev. Mater. 5, 124409 (2021). [6] S. Yamagishi et al., Chem. Mater. 35, 747 (2023).