title: Metamagnetic quantum criticality revealed by 17O-NMR in the itinerant metamagnet Sr3Ru2O7.
abstract: We have investigated the spin dynamics using 17O-NMR in the bilayered perovskite Sr3Ru2O7, which sits close to a metamagnetic quantum critical point. The nuclear spin-lattice relaxation rate divided by temperature 1/T1T is enhanced on approaching the metamagnetic critical field of approximately 7.9 T, and at the critical field 1/T1T continues to increase and does not show Fermi-liquid behavior down to 0.3 K. The temperature dependence of T1T in this region suggests the critical temperature Theta to be approximately 0 K, which is strong evidence that the spin dynamics possesses a quantum critical character. Comparison between uniform susceptibility and 1/T1T reveals that antiferromagnetic fluctuations instead of two-dimensional ferromagnetic fluctuations dominate the spin fluctuation spectrum at the critical field, which is unexpected for itinerant metamagnetism.
authors.affiliation: Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kitagawa
authors.forename: K
authors.initials: K
authors.lastname: Ishida
authors.forename: R S
authors.initials: RS
authors.lastname: Perry
authors.forename: T
authors.initials: T
authors.lastname: Tayama
authors.forename: T
authors.initials: T
authors.lastname: Sakakibara
authors.forename: Y
authors.initials: Y
authors.lastname: Maeno