Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session U61: Metal-Insulator transition in 4d/5d oxides
2:30 PM–5:30 PM,
Thursday, March 5, 2020
Room: Mile High Ballroom 4B
Sponsoring Units: DMP DCMP
Chair: Hallas Alannah
Abstract: U61.00001 : Emergent transport properties on the verge of metal-insulator transitions in pyrochlore 5d/4d oxides*
(Univ of Tokyo)
(Univ of Tokyo)
A variety of 5d/4d oxides, in which the magnitude of the relativistic spin-orbit coupling is comparable to that of the electron correlation, are suggested to host such a topologically-nontrivial property. For instance, pyrochlore iridates (R2Ir2O7) are firstly proposed as a candidate for the magnetic Weyl semimetal. Recent studies uncover that Nd2Ir2O7 shows salient magnetotransport properties on the verge of metal-insulator transitions, attributable to the realization of multiple topological semimetals with different magnetic ordering patterns. Here, we report another examples of such states in Pr2Ir2O7, which is known as a paramagnetic Luttinger semimetal. The resistivity is largely enhanced in the 3-in 1-out magnetic configuration of Pr-4f moments, whereas it is relatively small in the magnetically metastable state (so-called Kagome-ice state) accompanied with the plateau structure of Hall resistivity. It indicates that the quadratic-band-touching electronic structure is significantly sensitive to the localized magnetic configurations even in the weak-coupling system.
We also demonstrate that the pyrochlore 4d oxides provide a fertile playground. Particularly, Ruthenates (A2+2Ru5+2O7: 4d3or R3+2Ru4+2O7: 4d4) exhibit wide range of magnetic/electronic phases from an antiferromagnetic insulator to a ferromagnetic-like metal as the valence of A site changes. Furthermore, the sizable anomalous Hall conductivity is observed in the intermediate A-site composition, which can be understood in the context of the topological nature of the band structures.
*This work was supported by JSPS Grant-in-Aid for Scientific Research (No. 26103006, No. 24224009, and 19K14647) from the MEXT, and by CREST (No. JPMJCR16F1 and JPMJCR1874), JST, Japan.
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