Pressure and magnetic-field effects on metal-insulator transitions of bulk and domain-wall states in pyrochlore iridates
Autor: | Yoshinori Tokura, C. Terakura, Kentaro Ueda, Jun Fujioka |
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Jazyk: | angličtina |
Rok vydání: | 2015 |
Předmět: |
Physics
Condensed Matter::Quantum Gases Ionic radius Electronic correlation Condensed matter physics Magnetic domain Strongly Correlated Electrons (cond-mat.str-el) Pyrochlore FOS: Physical sciences Charge (physics) engineering.material Condensed Matter Physics Electronic Optical and Magnetic Materials Mott transition Paramagnetism Condensed Matter - Strongly Correlated Electrons Domain wall (magnetism) engineering Condensed Matter::Strongly Correlated Electrons |
Popis: | We have explored metal-insulator phenomena for pyrochlore ${R}_{2}{\mathrm{Ir}}_{2}{\mathrm{O}}_{7}$, in which the electron correlation strength and magnetic configuration are systematically controlled by varying the average rare-earth ionic radius $(R={\mathrm{Nd}}_{1\ensuremath{-}x}{\mathrm{Pr}}_{x}$ and ${\mathrm{Sm}}_{y}{\mathrm{Nd}}_{1\ensuremath{-}y})$, external pressure, and magnetic field. Metal-insulator transitions in bulk are caused by increasing $x$ or tuning pressure, indicating that the effective correlation is responsible for the transition. The metallic state intervenes between the paramagnetic insulating and antiferromagnetically ordered insulating phases for $({\mathrm{Sm}}_{y}{\mathrm{Nd}}_{1\ensuremath{-}y}){}_{2}{\mathrm{Ir}}_{2}{\mathrm{O}}_{7}$ $(y=0.7--0.9)$, reminiscent of a first-order Mott transition. Furthermore, the metal-to-insulator crossover is observed (around $y=0.7$) for charge transport on magnetic domain walls in the insulating bulk. An application of magnetic field also drives metal-insulator transitions for $({\mathrm{Nd}}_{1\ensuremath{-}x}{\mathrm{Pr}}_{x}){}_{2}{\mathrm{Ir}}_{2}{\mathrm{O}}_{7}$, which is likely due to the modulation of Ir $5d$ band structures accompanied by a change in the spin textures. Abundant exotic states are revealed in the vicinity of metal-insulator transitions by finely tuning the physical parameters in ${R}_{2}{\mathrm{Ir}}_{2}{\mathrm{O}}_{7}$. |
Databáze: | OpenAIRE |
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