【公開日：2024.07.25】【最終更新日：2024.06.21】
課題データ / Project Data
課題番号 / Project Issue Number
23QS0106
利用課題名 / Title
Exploring orbital excitations in bulk pyrochlore rhenates
利用した実施機関 / Support Institute
量子科学技術研究開発機構 / QST
機関外・機関内の利用 / External or Internal Use
外部利用/External Use
技術領域 / Technology Area
【横断技術領域 / Cross-Technology Area】（主 / Main）計測・分析/Advanced Characterization（副 / Sub）-
【重要技術領域 / Important Technology Area】（主 / Main）量子・電子制御により革新的な機能を発現するマテリアル/Materials using quantum and electronic control to perform innovative functions（副 / Sub）-
キーワード / Keywords
orbital excitations,放射光/ Synchrotron radiation,量子効果/ Quantum effect,超伝導/ Superconductivity
利用者と利用形態 / User and Support Type
利用者名（課題申請者）/ User Name (Project Applicant)
Xun Jia
所属名 / Affiliation
Institute of High Energy Physics, Chinese Academy of Sciences
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
Michael Terilli,Yujun Zhang,Guo Zhiying,Qianshun Diao
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
石井 賢司
利用形態 / Support Type
（主 / Main）共同研究/Joint Research（副 / Sub）-
利用した主な設備 / Equipment Used in This Project
報告書データ / Report
概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)
The 5d pyrochlore oxides are a family of materials that exhibit several tunable quantum phases, including those with non-trivial electronic and magnetic collective phenomena. Among them, Cd2Re2O7 (CRO) has recently drawn significant interest, including the identification of a hidden nematic phase. CRO is a correlated metal and undergoes a structural transition from centrosymmetric Fd-3m space group (phase I) to the I-4m2 (phase II) at Ts1 = 200 K [1]. Since phase II is noncentrosymmetric, the structural transformation is expected to be accompanied by transitioning into a topological state and potentially exotic superconductivity at low temperatures [2]. Recently, the low temperature phase was characterized as hosting multipolar nematic electronic order deviating from the symmetry of the lattice [3]. Moreover, theoretical analysis yielded that the phase below Ts1 may exhibit all-in-all-out (AIAO) magnetic order, which is yet to be experimentally confirmed [4]. Experimental exploration is further complicated by the availability of materials.This proposal seeks to illuminate (a) the nature of the magnetic order and correlation, as well as (b) the evolution of the electronic structure across the phase transition. We will use resonant inelastic X-ray spectroscopy (RIXS) to address both questions. Specifically, to address (a), we will explore the existence of possible magnetic excitations in CRO, especially along the [111] direction with magnetic peaks from the proposed AIAO magnetic peak. Moreover, we will track the evolution of orbital excitations that arise due to the strong spin-orbit coupling. The energy and width of the dd features will shed light into the orbital occupation. The proposed study is enabled by our recent success in obtaining magnetic excitations from pyrochlore iridates with AIAO ground states, including the observation of a persistent paramagnon surviving above the Neel temperature. Also, we have obtained high-quality large-size single crystals of CRO that are approximately 1mm in each direction that is sufficiently large for the proposed measurements.
実験 / Experimental
We use an incident photon energy around 10.537 keV (Re L3-edge) following [6], with a total energy resolution ~80 meV. 1. a XAS curve is taken to confirm the resonant photon energy and an energy loss scan is to confirm the energy resolution. The fixed incident energy is chose as 10.5415 keV; 2. when doing RIXS experiment, horizontal scattering geometry with pi polarization is used. We choose the incidence angle no smaller than 45 deg to minimize the contribution of horizontal photon footprint to the energy resolution. After alignning the CRO crystal carefully, we collect data around the (7 7 7) Bragg peaks, with tth ~ 90 deg. Two types of RIXS scans are taken during the beamtime, which are:1) RIXS map is taken at room temperature and RIXS curve with Ei fixed at 10.5415 keV are taken at 8 K and 160 K, respectively;2) momentum-resolved RIXS curves along Gamma-L direction at 8 K. During these RIXS measurements, phase plate is used to take resolution function for the use of elastic line's energy calibration.
結果と考察 / Results and Discussion
1. the full information of dd excitations is obtained. The intra-t2g excitation, t2g-eg excitation and charge transfer is obtained from the data.
2. Temperature-dependent of these dd excitations across the phases is obatined.
3. Momentum-dependent of these excitations is obtained.
Data analysis is on-going to figure out the nature of these observed excitations and the corresponding temperature-dependent behavior.
図・表・数式 / Figures, Tables and Equations
その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)
References:
[1] Jesse C. Petersen, et al., Nature Physics 2, 605-608 (2006).
[2] I. A. Sergienko, & S. H. Curnoe, J. Phys. Soc. Jpn 72, 1607-1610 (2003).
[3] J. W. Harter et al., Science 356, 295-299 (2017).
[4] S. Di Matteo and M. R. Norman, Phys. Rev. B 96, 115156 (2017).
[5] L. Chaix et al., Nature Physics 13, 952-956 (2017). H. Miao et al., PNAS 114, 12430-12435 (2017).
[6] Arun Paramekanti, et al., Phys. Rev. B 97, 235119 (2018).
成果発表・成果利用 / Publication and Patents
論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)
口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.
特許 / Patents
特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件