An unexpected gap Magnetic structures of La2O3 Fe1 xMnx 2Se2 investigated by neutron diffraction and physical property measurements

We prepared a solid solution of La2O3 Fe1 xMnx 2Se2 and performed elastic neutron diffraction experiments at 2 K, measured the magnetization from 2 to 300 K at 500 Oe and 10 T, and also performed resistivity measurements for selected samples. Our experiments show that atomic disorder and magnetic competition open a gap in the magnetic transition from the AFM3 order x lt;0.1 to the AFM1 order x amp; 10878;0.3 while the transition from AFM1x 0.3 lt;x amp; 10877;0.9 to AFM1z x gt;0.9 appears to be seamless. The compositions at 0.10 lt;x lt;0.25 did not show any long range magnetic order in neutron scattering experiments and are semiconducting to insulating until 2 K. However, material with this composition may be a very interesting candidate for further investigations due to the high degree of magnetic competition in this range of the La2O3 Fe1 xMnx 2Se2 syste