Unconventional transport properties of an itinerant ferromagnet: EuTi${}_{1-x}$Nb${}_x$O${}_3$ ($x$=0.10$-$0.20)

Abstract

We report the temperature and magnetic field dependence of resistivity ($\rho$) for single-crystalline EuTi${}_{1-x}$Nb${}_x$O${}_3$ ($x$=0.10$-$0.20), an itinerant ferromagnetic system with very low Curie temperature ($T_C$). The detailed analysis reveals that the charge conduction in EuTi${}_{1-x}$Nb${}_x$O${}_3$ is extremely sensitive to Nb concentration and dominated by several scattering mechanisms. Well below the $T_C$, where the spontaneous magnetization follows the Bloch's $T^{3/2}$ law, $\rho$ exhibits $T^2$ dependence with a large coefficient $\sim$10${}^{-8}$ $\Omega$ cm K${}^{-2}$ due to the electron-magnon scattering. Remarkably, all the studied samples exhibit a unique resistivity minimum at $T$$=$$T_{\min }$ below which $\rho$ shows logarithmic increment with $T$ (for $T_{\mathrm{C}}$$<$$T$$<$$T_{\min }$) due to the Kondo scattering of Nb 4$d^1$ itinerant electrons by the localized 4$f$ moments of Eu${}^{2+}$ ions which suppresses strongly with applied magnetic field. In the paramagnetic state, $T^2$ and $T^{3/2}$ dependence of the resistivity have been observed, suggesting an unusual crossover from a Fermi-liquid to a non-Fermi-liquid behavior with increasing $T$. The observed temperature and magnetic field dependence of resistivity has been analysed using different theoretical models.

13 pages, 9 figures

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• Heavy Fermions and Quantum Phase Transitions
• Metallic Quantum Ferromagnets
• Scalable T^2 resistivity in a small single-component Fermi surface
• CeRuPO: A rare example of a Ferromagnetic Kondo lattice
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• Structural and magnetic phase transitions in EuTi1-xNbxO3
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Cited by in corpus (3)

• Unusual magnetotransport and anomalous Hall effect in quasi-two-dimensional van der Waals ferromagnet Fe${}_4$GeTe${}_2$
• High spin-polarization in the low Curie temperature complex itinerant ferromagnet EuTi${}_{1-x}$Nb${}_x$O${}_3$
• Metallic ferroelectric-ferromagnetic multiferroics in strained EuTiO${}_{3-x}$H${}_x$