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arXiv 2403.07574cond-mat.mes-hallcond-mat.str-el
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强t-e轨道杂化的直接观测及f轨道的效应

Direct observation of strong t-e orbital hybridization and the effects of f orbitals

Wang Mian, Qian Zhang, Shuai Jing, Xiang-Guo Li, Yanglong Hou

AI总结:

本研究通过第一性原理方法在钙钛矿分子类似物$\textrm{Ce}_3\textrm{Cr}_8$中观测到强t-e轨道杂化引发的主导铁磁超交换作用,揭示了结构畸变对基态磁性的调控规律及Ce-f轨道的调制效应,完善了超交换磁性理论并提供了纳米磁调控新方向。

摘要:

近期研究表明,铬基钙钛矿ReCrO$_3$的Cr离子对中存在特殊的磁耦合相互作用,由于Cr$^\textrm{III}$离子间的t-e杂化,该耦合可能不符合Goodenough-Kanamori(GK)规则。我们采用第一性原理方法,研究了钙钛矿分子类似物[$\textrm{Ce}_2^\textrm{III}\textrm{Ce}^\textrm{IV}\textrm{Cr}_8^\textrm{III}\textrm{O}_8(\textrm{O}_2\textrm{CPh})_{18}(\textrm{HO}_2\textrm{CPh})$]($\textrm{Ce}_3\textrm{Cr}_8$)中同时涉及t-e杂化与Re-f轨道的复杂磁性。结果显示,与块体ReCrO$_3$不同,由于分子结构畸变引发的强t-e杂化,$\textrm{Ce}_3\textrm{Cr}_8$中经由Cr-d与O-p轨道的超交换作用呈现出意外的主导铁磁(FM)Cr-O-Cr超交换相互作用。t-e杂化对分子结构(如Cr-O-Cr键角)具有高度敏感性,随Cr-O-Cr键角变化,体系基态可发生从铁磁态到反铁磁态的转变。费米能级附近的Ce-f轨道可通过虚电荷转移过程与Cr-d轨道相互作用,从而降低这种敏感性。基于t-e杂化理论的修正超交换模型为我们的结果提供了有力支撑。这些发现完善了涉及t-e杂化与f轨道的超交换磁性理论,同时为在纳米尺度通过过渡金属d/稀土f相互作用精细调控磁特性开辟了新途径。

英文摘要:

Recent research has revealed that the Cr family perovskite ReCrO$_3$ exhibits intriguing magnetic coupling interactions within Cr pairs, which may not follow the Goodenough-Kanamori (GK) rules due to the t-e hybridization between Cr$^\mathrm{III}$ ions. We investigate the complex magnetism involving both t-e hybridization and Re-$f$ orbitals in the molecular analogue of perovskite [$\mathrm{Ce_2^{III}Ce^{IV}Cr_8^{III}O_8(O_2CPh)_{18}(HO_2CPh)}$] ($\mathrm{Ce_3Cr_8}$) using first-principles method. Our results have shown that distinct from the bulk ReCrO$_3$, the superexchange via Cr-$d$ and O-$p$ orbitals can exhibit a unexpected dominate ferromagnetic (FM) Cr-O-Cr superexchange interaction in $\mathrm{Ce_3Cr_8}$ due to the strong t-e hybridization originated from the distorted molecular structure. The great sensitivity of the t-e hybridization with respect to the molecular structure, e.g., the angle of Cr-O-Cr, can lead to a ground state transition from ferromagnetic to antiferromagnetic state with the changes in the angle of Cr-O-Cr. The Ce-$f$ orbitals near the Fermi level can reduce this sensitivity through interacting with the Cr-$d$ orbitals via the virtual charge transfer process. Our results are strongly supported by a modified superexchange model based on the t-e hybridization theory. These findings complete the theory of superexchange magnetism involving the t-e hybridization and $f$ orbitals, and in the meanwhile introduce a new avenue for fine-tuning the magnetic characteristics via Tm-d/Re-f interactions at nanoscale.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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