NMR study on the quasi-one dimensional antiferromagnet BaCo2Si2O7

NMR study has been performed on the quasi-one dimensional antiferromagnet BaCo2Si2O7, in which three inequivalent CoO4 tetrahedra, slightly tilted from one another, are linked at vertices to form a chain along the easy-axis c. In its magnetically ordered state at 3.6 K, Co-59-NMR spectra were measured in the field region up to 12 T. From the observed three distinct sets of quadrupolar-split peak groups, three different hyperfine fields at Co sites were determined. They are slightly tilted from c-axis and are all different both in magnitude and direction, which is in agreement with the non-collinear magnetic structure.