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arXiv · 2012.03251

Evolution of possible Weyl semimetal states across the hole-doping induced Mott transition in pyrochlore iridates

Kentaro Ueda·Hikaru Fukuda·Ryoma Kaneko·Jun Fujioka·Yoshinori Tokura
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Abstract

We study possible Weyl semimetals of strongly-correlated electrons by investigating magnetotransport properties in pyrochlore R2Ir2O7 (R=rare-earth ions), choosing three types of R ions to design the exchange coupling scheme between R 4f and Ir 5d moments; non-magnetic Eu (4f6), isotropic Gd (4f7), and anisotropic Tb (4f8). In the doping-induced semimetallic state, distinctive features of magnetoresistance and Hall effect are observed in R=Gd and Tb compounds due to the effects of the exchange-enhanced isotropic and anisotropic Zeeman fields, respectively, exemplifying the double Weyl semimetal and the 2-in 2-out line-node semimetal as predicted by theories. In particular, a Hall angle of R=Gd compound is strongly enhanced to 1.5 % near above the critical doping for the Mott transition. Furthermore, an unconventional Hall contribution is discerned for a lower doping regime of R=Gd compound, which can be ascribed to the emergence of Weyl points with the field-distorted all-in all-out order state. These findings indicate that the hole-doping induced Mott transition as well as the characteristic f-d exchange interaction stabilizes versatile topological semimetal states in a wide range of material parameter space.

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Kentaro Ueda, Hikaru Fukuda, Ryoma Kaneko, Jun Fujioka, Yoshinori Tokura. 2020-12-06. Evolution of possible Weyl semimetal states across the hole-doping induced Mott transition in pyrochlore iridates. https://doi.org/10.1103/physrevb.102.245131

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