Synthesis of fine particles of a geometrically frustrated spin-chain system Ca₃Co₂O₆ through a pyrophoric route and its magnetic behavior

Abstract

We report the synthesis of fine particles of a well-known geometrically frustrated spin-chain compound Ca₃Co₂O₆ through a new route, namely, a pyrophoric method employing triethanolamine (TEA) and studied the magnetic behavior of such specimens. We find that this method of synthesis yields particles made up of rods whose diameter appears to be controllable by the fraction of TEA during synthesis. It is seen that the two well-known magnetic transitions (~24 K and ~8 K) remains unaffected for all TEA concentrations used. The most notable finding is that the multi-step feature in the M versus magnetic-field isotherm reported for the single crystalline form tends to smoothen out gradually with decreasing rod thickness (from about 1 μm to a few hundred nm). Further, unlike for the single crystalline form known in the literature, there is no tendency for the relaxation time (t) to remain constant at low temperatures ( < 10 K) and t remains temperature dependent up to the lowest temperature measured (1.8 K) in all the specimens. These findings suggest that the multi-step magnetization anomaly in this system may be characterized by a magnetic correlation length.