Magnetic and transport properties of the pyrochlore iridates (Y1−xPrx)2Ir2O7 : Role of f−d exchange interaction and d−p orbital hybridization
| Autor: | K. Asokan, K. C. Kharkwal, Harish Kumar, Kranti Kumar, A. Banerjee, Ashim Pramanik |
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| Rok vydání: | 2020 |
| Předmět: |
Physics
Absorption spectroscopy Magnetoresistance Geometrical frustration Exchange interaction Pyrochlore 02 engineering and technology engineering.material 021001 nanoscience & nanotechnology 01 natural sciences Crystallography Atomic orbital 0103 physical sciences Exponent engineering Condensed Matter::Strongly Correlated Electrons Ideal (ring theory) 010306 general physics 0210 nano-technology |
| Zdroj: | Physical Review B. 101 |
| ISSN: | 2469-9969 2469-9950 |
| DOI: | 10.1103/physrevb.101.064405 |
| Popis: | The $f\text{\ensuremath{-}}d$ magnetic exchange interaction is considered to be a key ingredient for many exotic topological phases in pyrochlore iridates. Here, we have investigated the evolution of structural, magnetic, and electronic properties in doped pyrochlore iridate, ${({\mathrm{Y}}_{1\ensuremath{-}x}{\mathrm{Pr}}_{x})}_{2}{\mathrm{Ir}}_{2}{\mathrm{O}}_{7}$. Apart from geometrical frustration, pyrochlore iridates are well known for their active spin-orbit-coupling effect. The substitution of ${\mathrm{Pr}}^{3+}\phantom{\rule{4pt}{0ex}}(4{f}^{2})$ for the nonmagnetic ${\mathrm{Y}}^{3+}\phantom{\rule{4pt}{0ex}}(4{d}^{0})$ acts as a magnetic doping, which provides an ideal platform to study $f\text{\ensuremath{-}}d$ exchange interaction without altering the Ir sublattice. With Pr substitution, the system retains its original cubic structural symmetry, but the local structural parameters show an evolution with the doping concentration $x$. The robust magnetic-insulating state in ${\mathrm{Y}}_{2}{\mathrm{Ir}}_{2}{\mathrm{O}}_{7}$ is drastically weakened, while ${\mathrm{Pr}}_{2}{\mathrm{Ir}}_{2}{\mathrm{O}}_{7}\phantom{\rule{4pt}{0ex}}(x=1.0)$ shows a paramagnetic-metallic behavior. A metal-insulator transition is observed for the $x=0.8$ sample. This evolution of magnetic and electronic properties is believed to be induced by an exchange interaction between localized Pr-$4f$ and itinerant Ir-$5d$ electrons, as well as by an increased hybridization between Ir-${t}_{2g}$ and (basal) O-$p$ orbitals, as observed in x-ray absorption spectroscopy study. The resistivity in insulating materials follows a power-law behavior with a decreasing exponent with $x$. A negative magnetoresistance is observed for the present series of samples at low temperature and where the magnetoresistance shows a quadratic field dependence at higher fields. |
| Databáze: | OpenAIRE |
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