Cyclotron resonance study of quasiparticle mass and scattering rate in the hidden-order and superconducting phases of URu2Si2

Abstract

The observation of cyclotron resonance in ultra-clean crystals of URu2Si2 [S. Tonegawa et al., PRL 109, 036401 (2012)] provides another route besides quantum oscillations to the determination of the bulk electronic structure in the hidden order phase. We report detailed analyses of the resonance lines, which fully resolve the cyclotron mass structure of the main Fermi surface sheets. A particular focus is given to the anomalous splitting of the sharpest resonance line near the [110] direction under in-plane magnetic-field rotation, which implies peculiar electronic structure in the hidden order phase. The results under the field rotation from [110] toward [001] direction reveal that the splitting is a robust feature against field tilting from the basal plane. This is in sharp contrast to the reported frequency branch alpha in the quantum oscillation experiments showing a three-fold splitting that disappears by a small field tilt, which can be explained by the magnetic breakdown between the large hole sphere and small electron pockets. Our analysis of the cyclotron resonance profiles reveals that the heavier branch of the split line has a larger scattering rate, providing evidence for the existence of hot-spot regions along the [110] direction. These results are consistent with the broken fourfold rotational symmetry in the hidden-order phase, which can modify the interband scattering in an asymmetric manner. We also extend our measurements down to 0.7 K, which results in the observation of cyclotron resonance in the superconducting state, where novel effects of vortex dynamics may enter. We find that the cyclotron mass undergoes no change in the superconducting state. In contrast, the quasiparticle scattering rate shows a rapid decrease below the vortex-lattice melting transition temperature, which supports the formation of quasiparticle Bloch state in the vortex lattice phase.

15 pages, 12 figures

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Cited by in corpus (10)

• Hidden Order Behaviour in URu2Si2 (A Critical Review of the Status of Hidden Order in 2014)
• Direct observation of lattice symmetry breaking at the hidden-order transition in URu2Si2
• Evidence for chiral d-wave superconductivity in URu2Si2 from the field-angle variation of its specific heat
• Broken symmetries in URu2Si2
• Local observation of linear-$T$ superfluid density and anomalous vortex dynamics in URu${}_2$Si${}_2$
• Fermi surface in the hidden-order state of URu${}_2$Si${}_2$ under intense pulsed magnetic fields up to 81~T
• Fermi-Surface Selective Determination of the $\mathbf{g}$-Factor Anisotropy in URu${}_2$Si${}_2$
• Inelastic x-ray scattering measurements on URu2Si2
• Magnetoelastic phenomena in antiferromagnetic uranium intermetallics: the $\mathrm{UA}{\mathrm{u}}_2\mathrm{S}{\mathrm{i}}_2$ case
• Phenomenological theory of the superconducting state inside the hidden-order phase of URu${}_2$Si${}_2$