title: New magnetic phase diagram of (Sr,Ca)2RuO4.
abstract: High-T(c) cuprates, iron pnictides, organic BEDT and TMTSF, alkali-doped C(60), and heavy-fermion systems have superconducting states adjacent to competing states exhibiting static antiferromagnetic or spin density wave order. This feature has promoted pictures for their superconducting pairing mediated by spin fluctuations. Sr(2)RuO(4) is another unconventional superconductor which almost certainly has a p-wave pairing. The absence of known signatures of static magnetism in the Sr-rich side of the (Ca, Sr) substitution space, however, has led to a prevailing view that the superconducting state in Sr(2)RuO(4) emerges from a surrounding Fermi-liquid metallic state. Using muon spin relaxation and magnetic susceptibility measurements, we demonstrate here that (Sr,Ca)(2)RuO(4) has a ground state with static magnetic order over nearly the entire range of (Ca, Sr) substitution, with spin-glass behaviour in Sr(1.5)Ca(0.5)RuO(4) and Ca(1.5)Sr(0.5)RuO(4). The resulting new magnetic phase diagram establishes the proximity of superconductivity in Sr(2)RuO(4) to competing static magnetic order.
authors.affiliation: Department of Physics, Columbia University, New York, New York 10027, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Carlo
authors.forename: T
authors.initials: T
authors.lastname: Goko
authors.forename: I M
authors.initials: IM
authors.lastname: Gat-Malureanu
authors.forename: P L
authors.initials: PL
authors.lastname: Russo
authors.forename: A T
authors.initials: AT
authors.lastname: Savici
authors.forename: A A
authors.initials: AA
authors.lastname: Aczel
authors.forename: G J
authors.initials: GJ
authors.lastname: MacDougall
authors.forename: J A
authors.initials: JA
authors.lastname: Rodriguez
authors.forename: T J
authors.initials: TJ
authors.lastname: Williams
authors.forename: G M
authors.initials: GM
authors.lastname: Luke
authors.forename: C R
authors.initials: CR
authors.lastname: Wiebe
authors.forename: Y
authors.initials: Y
authors.lastname: Yoshida
authors.forename: S
authors.initials: S
authors.lastname: Nakatsuji
authors.forename: Y
authors.initials: Y
authors.lastname: Maeno
authors.forename: T
authors.initials: T
authors.lastname: Taniguchi
authors.forename: Y J
authors.initials: YJ
authors.lastname: Uemura