Magnetic properties of the CoS_2-xSe_xcompounds. I. Concentration and temperature effects on the 'metamagnetic' transition

Evidence of kinetic arrest in Se doped CoS2

“…Powder x-ray diffraction measurement is carried out to check phase purity and lattice parameter. Absence of un-indexed peak indicates single phase nature of the sample and unit cell parameter is found to be 0.5578 nm, which is in good agreement with the existing literature [12,40,2]. Resistivity measurements are carried out by standard four-probe technique using a homemade resistivity setup along with 8 T superconducting magnet system from Oxford Instruments, UK.…”

Magnetic properties of the itinerant metamagnetic systemCo(S1−xSexGoto1, Shindo2, Takahashi3 et al. 1997Phys. Rev. B1049620View full textAdd to dashboardCite

“…We know from previous experiments that the field and the temperature dependence of the magnetization of a metamagnetic sample in the range 0.1рxр0.2 are extremely sensitive to the local arrangement of S and Se atoms around the Co atom. 26,27 Since we aimed to obtain the precise magnetization data of Co(S 1Ϫx Se x ) 2 to compare quantitatively their transition temperatures and critical fields with the theory, we needed to have very good homogeneous samples. In several trials of sample preparation, we found a small amount of selenium segregation and condensations separately in an evacuated quartz tube when the reaction temperature was high, above about 650°C.…”

Itinerant electron metamagnetism

“…RCo2 [10,1], where R means the rare earth metals and is Dy, Ho or Er, (Ho, Y)Co2 [12], etc., which show MT from the paramagnetic state to the ferromagnetic state and also many compounds, e.g. ThCo5 [13], Y2Ni16 [14], Co(S, Se)2 [15,16], (Co, Ni)S2 [17], etc. show MT from the weak ferromagnetic state to the ferromagnetic state with a larger magnetization.…”

“…In the case of Co(S, Se)2 [15,16] and (Co, Ni)S2 [17], the simple Heisenberg model seems to be appropriate, because the magnetization changes very little at very high field or the high-field susceptibility is very small and the temperature variation of x at high temperatures obeys the Curie-Weiss law. However, all the coefficients except the first coefficient of the M 2 term in the expansion of the free energy as a power series of M2 in the molecular field approximation are always positive in the simple Heisenberg model, where the average of the magnetic interaction is proportional to M2, so that we cannot expect MT and the firstorder transition in this model.…”

“…the magnetic interaction with higher powers of M than M2, the temperature dependence of the molecular field coefficient, the complicated magnetic structures, the distribution of the magnetic moments, etc. In the case of Co(SxSe1-.J2 compounds the distribution of cobalt atoms with and without magnetic moment has been ascertained in experiment [16] and MT has been discussed in terms of the distribution of the two kinds of Co atoms with and without magnetic moment [24,25]. In section 2, general conditions for MT based on the thermodynamics are shown without regard to any specific model for MT.…”