High-pressure investigations of the itinerant ferromagnet

High-pressure study of the phase transition in the itinerant ferromagnetCoS2

“…From these experiments, we find that a tricritical point does exist on the phase-transition line, probably close to ambient pressure and further that a strongly first-order quantum-phase transition from the ferromagnetic to the paramagnetic states in CoS 2 is located at 4.79 GPa. In contrast to an earlier report 12 , there is no deviation from Fermi liquid behavior in CoS 2 at high pressures.…”

“…4 and compare it with available literature data. Our low pressure data agree nicely with early results 9,17,18 , but the striking disagreement with high pressure data of Barakat et al 12 probably can be understood as a result of pressure inhomogeneity generated by the steatite pressure medium used for those measurements and difficulties with a precise determination of the transition point, as mentioned by these authors. It is clearly seen in Fig.…”

“…In particular, a nonFermi liquid temperature variation in resistivity is expected in the quantum-critical regime, which is claimed in Ref. 12 . Fitting the temperature dependence of resistivity ρ(T ) at different pressures in the range 1.3-6 K by the function ρ(T ) = ρ 0 + AT n yields pressure dependences of the parameters ρ 0 , A, and n that are depicted in Fig.…”

Thermodynamics of the ferromagnetic phase transition in nearly half metallic CoS2 at high pressures

“…Upon entering the ferromagnetic state CoS 2 becomes a nearly half metal with a significant decrease in the density of states at the Fermi level that is reflected in an increase in the resistivity below T c [7,8]. The temperature-pressure phase diagram of CoS 2 has been studied to high pressures where experiments show that the ferromagnetic transition decreases monotonically and trends to zero at ∼6 GPa [9,10,11,12]. A change from continuous to first-order phase transition with a tricritical point close to ambient pressure was suggested in Refs.…”

Evidence of kinetic arrest in Se doped CoS2

“…due to reduction in the density of state at Fermi level of minority spin band [13,14]. With the application of pressure, T C is shifted to low temperature and appearance of thermal hysteresis indicates first order nature of the transition [15,16,10,17,18]. The nature of transition in CoS 2 under ambient pressure, itself has been a subject matter of debate [19,14,10,16].…”