Thermoelectricity of the Ferromagnetic Superconductor UCoGe

Abstract

UCoGe exhibits superconductivity in the presence of ferromagnetism. When a field is applied along the b axis (perpendicular to the easy axis), ferromagnetism is weakened and superconductivity is enhanced. This enhancement has been attributed to an increase in coupling as observed in the enhanced effective mass produced by the critical fluctuations as the ferromagnetic transition is strongly suppressed. However it is also important to know if and how the Fermi surface changes near the critical point. Here we report measurements of the thermoelectricity of UCoGe which reveal a low carrier density metal. Under magnetic field applied along the b axis, a sharp peak is observed in the thermopower of UCoGe at H*=11.1T and low temperature which becomes broader at higher temperatures. At higher field, the thermopower changes sign which suggests a modification of the Fermi Surface. We analyze these results using a topological change in Fermi surface and show that this can explain both the thermopower and the enhanced superconductivity.

Accepted for publication in Phys. Rev. B

References in corpus (8)

• Superconductivity on the border of weak itinerant ferromagnetism in UCoGe
• On the thermoelectricity of correlated electrons in the zero-temperature limit
• Ferromagnetism and Superconductivity in Uranium Compounds
• Tricritical point and wing structure in the itinerant ferromagnet UGe2
• Unusual upper critical field of the ferromagnetic superconductor UCoGe
• Field Re-entrant Superconductivity Induced by the Enhancement of Effective Mass in URhGe
• Thermoelectric response near a quantum critical point: the case of CeCoIn5
• Quantum Metamagnetic Transitions Induced by Changes in Fermi-Surface Topology -Applications to a Weak Itinerant-Electron Ferromagnet;ZrZn_2

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• Superconductivity and Ferromagnetic Quantum Criticality in Uranium Compounds
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• Fermi-Surface Instabilities in the Heavy-Fermion Superconductor UTe2
• Interplay of magnetism, Fermi surface reconstructions, and hidden-order in the heavy-fermion material URu${}_2$Si${}_2$
• Assessment of the U and Co magnetic moments in UCoGe by X-ray magnetic circular dichroism
• Relationship between Ferromagnetic Criticality and the Enhancement of Superconductivity Induced by Transverse Magnetic Fields in UCoGe
• Fermi Surface Instabilities in Ferromagnetic Superconductor URhGe
• Superconducting Gap of UCoGe probed by Thermal Transport
• Quantum criticality and Lifshitz transition in the Ising system CeRu2Si2: Comparison with YbRh2Si2
• Thermoelectric signature of quantum critical phase in a doped spin liquid candidate
• Enhanced Seebeck coefficient through the magnetic fluctuations in Sr${}_2$Ru${}_{1-x}{M}_x$O${}_4$ ($M=$ Co, Mn)
• Angular variation of the magnetoresistance of the superconducting ferromagnet UCoGe
• Multigap Superconductivity in the Ferromagnetic Superconductor UCoGe Revealed by Thermal Conductivity Measurements
• Giant Thermoelectric Response of Fluxons in Superconductors
• Magnetic Field Driven Electronic Singularities through Metamagnetic Phenomena: Case of the Heavy Fermion Antiferromagnet Ce(Ru0.92Rh0.08)2Si2