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Cooperative Phenomenon of Ferromagnetism and Unconventional Superconductivity in UGe$_2$: A ^73^Ge-NQR Study under Pressure

Atsushi Harada·Shinji Kawasaki·Hisashi Kotegawa·Yoshio Kitaoka·Yoshinori Haga·Etsuji Yamamoto·Yoshichika Onuki·Kouhei Itoh·Eugene Haller·Hisatomo Harima
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Abstract

We report on a cooperative phenomenon of ferromagnetism and unconventional superconductivity (SC) in UGe$_2$ through the measurements of $^{73}$Ge nuclear-quadrupole-resonance (NQR) under pressure ($P$). The NQR spectra evidenced phase separation into ferromagnetic and paramagnetic phases in the vicinity of $P_c\sim 1.5$ GPa, pointing to a first-order transition. The measurements of nuclear-spin-lattice-relaxation-rate $1/T_1$ revealed that SC emerges under the background of ferromagnetism, but not of the paramagnetic phase.

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Atsushi Harada, Shinji Kawasaki, Hisashi Kotegawa, Yoshio Kitaoka, Yoshinori Haga, Etsuji Yamamoto, Yoshichika Onuki, Kouhei Itoh, Eugene Haller, Hisatomo Harima. 2005-08-30. Cooperative Phenomenon of Ferromagnetism and Unconventional Superconductivity in UGe$_2$: A ^73^Ge-NQR Study under Pressure. https://doi.org/10.1143/jpsj.74.2675

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