Spiral magnetic structure in spin-5/2 frustrated trimerized chains in   SrMn3P4O14
  We study a spin-5/2 antiferromagnetic trimerized chain substance SrMn3P4O14 using neutron powder diffraction experiments. The coplanar spiral magnetic structure appears below T_N1 = 2.2(1) K. Values of several magnetic structure parameters change rapidly at T_N2 = 1.75(5) K, indicating another phase transition, although the magnetic structures above and below T_N2 are the qualitatively same. The spiral magnetic structure can be explained by frustration between nearest-neighbor and next-nearest-neighbor exchange interactions in the trimerized chains. 
Masashi Hase, Vladimir Yu. Pomjakushin, Lukas Keller, Andreas D\"onni,   Osamu Sakai, Tao Yang, Rihong Cong, Jianhua Lin, Ki...
cond-mat.str-el