Heat-capacity anomalies in the presence of high magnetic fields in the spin-chain compound, Ca₃Co₂O₆

Abstract

Heat-capacity behavior in the presence of externally applied magnetic field (H) up to 140 kOe is investigated (2-35 K) for the quasi-one-dimensional compound, Ca₃Co₂O₆, believed to order magnetically with the 'so-called' 'partially disordered anti-ferromagnetic structure'. The results reveal that there is a shift of the magnetic transition occurring around 24 K to a marginally higher temperature (by 0.5 K) as H is increased from 10 to 30 kOe, uncharacteristic of anti-ferromagnets. No peak, attributable to magnetic ordering could be observed in the entire field range of investigation in the vicinity of the second magnetic transition, occurring at around 10 K. However, hysteresis studies of H-dependence of C indicate a subtle change in the magnetic structure as the T is lowered across 10 K.