Horizontal line nodes in SrRuO proved by spin resonance

スピンレゾナンスにより実証されたSrRuOの水平ラインノード

飯田 一樹*; 古府 麻衣子   ; 鈴木 雄大*; 村井 直樹  ; 河村 聖子   ; 梶本 亮一  ; 稲村 泰弘  ; 石角 元志*; 長谷川 舜介*; 益田 隆嗣*; 吉田 良行*; 加倉井 和久*; 町田 一成*; Lee, S.*

Iida, Kazuki*; Kofu, Maiko; Suzuki, Katsuhiro*; Murai, Naoki; Kawamura, Seiko; Kajimoto, Ryoichi; Inamura, Yasuhiro; Ishikado, Motoyuki*; Hasegawa, Shunsuke*; Masuda, Takatsugu*; Yoshida, Yoshiyuki*; Kakurai, Kazuhisa*; Machida, Kazushige*; Lee, S.*

We investigated the low-energy incommensurate (IC) magnetic fluctuations in SrRuO by the high-resolution inelastic neutron scattering measurements and random phase approximation (RPA) calculations. We observed a spin resonance with energy of meV centered at a characteristic wavevector . The resonance energy corresponds well to the superconducting gap 2 = 0.56 meV estimated by the tunneling spectroscopy. The spin resonance shows the modulation with a maximum at around . The modulated intensity of the spin resonance and our RPA calculations indicate that the superconducting gaps regarding the quasi-one-dimensional and sheets at the Fermi surfaces have the horizontal line nodes. These results may set a strong constraint on the pairing symmetry of SrRuO. We also discuss the implications on possible superconducting order parameters.