Muon-spin rotation and relaxation study on the quasi-one-dimensional compounds Ca3 CoRh O6, Sr4 Co Rh2 O9, and Sr5 Co Rh3 O12

Abstract

Thanks to the unique power of muon-spin spectroscopy, we found that the quasi-one-dimensional Co-Rh oxides An+2 Co Rhn O3n+3 (A=Ca,Sr; n=1, 2, and 3) exhibit a two-dimensional antiferromagnetic transition that ranges from TNon =185 K for n=1 to 125 K for n=3 with a transition width (ΔT) of about 80 K. The variation of TNon with n is explained by the increase in the distance between the neighboring Co Rhn O3n+3 chains. Static magnetic order is observed below the end point of TN (= TNon -ΔT) for each of the three samples. The existence of the two-frequency components in the zero field spectrum indicates the appearance of ferrimagnetic order for Ca3 CoRh O6 below 20 K. © 2008 The American Physical Society.