Magnetic Excitations in the CE-type manganite Pr$_{0.5}$Ca$_{1.5}$MnO$_{4}$

Charge and orbital ordering (CO-OO) in doped manganites can control bulk and magnetic properties of the material. Canonical examples of the CO-OO compounds are 3D R(1-x)A(x)MnO3 and 2D R(1-x)A(1+x)MnO4 manganites near x=0.5. The magnetic ions in those systems are usually arranged in a checkerboard order, where spins of Mn3+ and Mn4+ form zigzap ferromagnetic chains coupling antiferromagnetically. Recent theoretical calculations and experimental observations suggest that the stabilization of CO-OO state in CE-type magnetic structure might be magnetic in origin. In this talk we will present our recent results on the study of the spin-wave excitations in the layered compound Pr0.5Ca1.5MnO4 with CE-type magnetic structure using inelastic neutron scattering. ORNL is managed by UT-Battelle, LLC, for the U.S. Dept. of Energy under contract DE-AC05-00OR22725. The work at UT was supported by the U.S. NSF DMR-0453804 and DOE DE-FG02-05ER46202.