Stability of the geometrically frustrated magnetic state of Ca₃CoRhO₆ to applications of positive and negative pressure

Abstract

The influence of negative chemical pressure induced by gradual replacement of Ca by Sr as well as of external pressure (up to 10 kbar) on the magnetism of Ca₃CoRhO₆ has been investigated by magnetization studies. It is found that the solid solution, Ca_3−xSr_xCoRhO₆, exists at least until about x=1.0 without any change in the crystal structure. Apart from insensitivity of the spin-chain feature to volume expansion, the characteristic features of geometrical frustration interestingly appear at the same temperatures for all compositions, in sharp contrast to the response to Y substitution for Ca (reported previously). Interestingly, the huge frequency dependence of ac susceptibility known for the parent compound persists for all compositions. We do not find a change in the properties under external pressure. The stability of the magnetic anomalies of this compound to volume change (about 4%) is puzzling.