Optical spectra of the heavy fermion uniaxial ferromagnet UGe${}_2$

Abstract

We report a detailed study of UGe${}_2$ single crystals using infrared reflectivity and spectroscopic ellipsometry. The optical conductivity suggests the presence of a low frequency interband transition and a narrow free-carrier response with strong frequency dependence of the scattering rate and effective mass. We observe sharp changes in the low frequency mass and scattering rate below the upper ferromagnetic transition $T_C=53K$. The characteristic changes are exhibited most strongly at an energy scale of around 12 meV (100 cm${}^{-1}$). They recover their unrenormalized value above $T_C$ and for $\omega >$ 40 meV. In contrast no sign of an anomaly is seen at the lower transition temperature of unknown nature $T_x\sim$ 30 K, observed in transport and thermodynamic experiments. In the ferromagnetic state we find signatures of a strong coupling to the longitudinal magnetic excitations that have been proposed to mediate unconventional superconductivity in this compound.

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Cited by in corpus (4)

• Electrodynamics of Correlated Electron Materials
• Low energy electrodynamics of the Kondo-lattice antiferromagnet CeCu${}_2$Ge${}_2$
• Coexisting Kondo hybridization and itinerant f-electron ferromagnetism in UGe2
• Spin-polaron band of heavy carriersin the heavy-fermion ferromagnetic superconductor UGe2