Fragile Magnetic Ground State in Half-Doped ${\mathrm{LaSr}}_{2}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}$

Fragile Magnetic Ground State in Half-Doped ${LaSr}_{2} {Mn}_{2} O_{7}$

J.-S. Lee, C.-C. Kao, C. S. Nelson, H. Jang, K.-T. Ko, S. B. Kim, Y. J. Choi, S.-W. Cheong, S. Smadici, P. Abbamonte, and J.-H. Park

Phys. Rev. Lett. 107, 037206 – Published 15 July 2011

Abstract

We investigated the orbital and antiferromagnetic ordering behaviors of the half-doped bilayer manganite ${La}_{2 - 2 x} {Sr}_{1 + 2 x} {Mn}_{2} O_{7}$ ( $x ≃ 0.5$ ) by using Mn $L_{2, 3}$ -edge resonant soft x-ray scattering. Resonant soft x-ray scattering reveals the $C E$ -type orbital order below $T_{oo} ≃ 220 K$ , which shows partial melting behavior below $T_{m} ≃ 165 K$ . We also found coexistence $C E$ - and $A$ -type antiferromagnetic orders. Both orders involve the $C E$ -type orbital order with nearly the same orbital character and are coupled with each other. These results manifest that the ground state with the $C E$ -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 $x ≃ 0.5 \pm 0.005$ .

Received 20 April 2011

DOI:https://doi.org/10.1103/PhysRevLett.107.037206

Authors & Affiliations

J.-S. Lee^1,*, C.-C. Kao¹, C. S. Nelson², H. Jang³, K.-T. Ko³, S. B. Kim⁴, Y. J. Choi⁵, S.-W. Cheong^5,6, S. Smadici⁷, P. Abbamonte⁷, and J.-H. Park^3,8,†

¹Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
²National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973, USA
³c-CCMR and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, South Korea
⁴Advancement for College Education Center, Konyang University, Chungnam 320-711, South Korea
⁵R-CEM and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
⁶l-PEM and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, South Korea
⁷Physics Department and Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA
⁸Division of Advanced Materials Science, Pohang University of Science and Technology, Pohang 790-784, South Korea