title: Fragile magnetic ground state in half-doped LaSr2Mn2O7.
abstract: We investigated the orbital and antiferromagnetic ordering behaviors of the half-doped bilayer manganite La(2-2x)Sr(1+2x)Mn2O7 (x ≃ 0.5) by using Mn L(2,3)-edge resonant soft x-ray scattering. Resonant soft x-ray scattering reveals the CE-type orbital order below T(oo) ≃ 220  K, which shows partial melting behavior below T(m) ≃ 165  K. We also found coexistence CE- and A-type antiferromagnetic orders. Both orders involve the CE-type orbital order with nearly the same orbital character and are coupled with each other. These results manifest that the ground state with the CE-type antiferromagnetic order is easily susceptible to destabilization into the A-type one even with a small fluctuation of the doping level, as suggested by the extremely narrow magnetic phase boundaries at x ≃ 0.5±0.005.
authors.affiliation: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA. jslee@slac.stanford.edu
authors.forename: J-S
authors.initials: JS
authors.lastname: Lee
authors.forename: C-C
authors.initials: CC
authors.lastname: Kao
authors.forename: C S
authors.initials: CS
authors.lastname: Nelson
authors.forename: H
authors.initials: H
authors.lastname: Jang
authors.forename: K-T
authors.initials: KT
authors.lastname: Ko
authors.forename: S B
authors.initials: SB
authors.lastname: Kim
authors.forename: Y J
authors.initials: YJ
authors.lastname: Choi
authors.forename: S-W
authors.initials: SW
authors.lastname: Cheong
authors.forename: S
authors.initials: S
authors.lastname: Smadici
authors.forename: P
authors.initials: P
authors.lastname: Abbamonte
authors.forename: J-H
authors.initials: JH
authors.lastname: Park