Evidence for ferromagnetic spin-pairing superconductivity in UGe${}_2$: A ${}^{73}$Ge-NQR study under pressure

Abstract

We report that a novel type of superconducting order parameter has been realized in the ferromagnetic states in UGe${}_2$ via ${}^{73}$Ge nuclear-quadrupole-resonance (NQR) experiments performed under pressure ($P$). Measurements of the nuclear spin-lattice relaxation rate $(1/T_1)$ have revealed an unconventional nature of superconductivity such that the up-spin band is gapped with line nodes, but the down-spin band remains gapless at the Fermi level. This result is consistent with that of a ferromagnetic spin-pairing model in which Cooper pairs are formed among ferromagnetically polarized electrons. The present experiment has shed new light on a possible origin of ferromagnetic superconductivity, which is mediated by ferromagnetic spin-density fluctuations relevant to the first-order transition inside the ferromagnetic states.

arXiv comment5 pages, 5 figures

References in corpus (7)

• Pressure dependence of the magnetization in the ferromagnetic superconductor UGe_2
• Theory of Ferromagnetic Superconductivity
• Coupled CDW and SDW Fluctuations as an Origin of Anomalous Properties of Ferromagnetic Superconductor UGe_2
• Magnetic Properties of a Pressure-induced Superconductor UGe${}_2$
• Evidence for Uniform Coexistence of Ferromagnetism and Unconventional Superconductivity in UGe_2: A ^73Ge-NQR Study under Pressure
• Cooperative Phenomenon of Ferromagnetism and Unconventional Superconductivity in UGe${}_2$: A ^73^Ge-NQR Study under Pressure
• Heat Capacity of the Pressure-induced Superconductivity in Itinerant Ferromagnet UGe${}_2$

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