The magnetic properties of spinel GeNi2-2x Co2x O4 systems in the range 0 ≤ x ≤1 are studied by mean field theory and high-temperature series expansions. The nearest neighbouring and the next-neighbouring superexcha...The magnetic properties of spinel GeNi2-2x Co2x O4 systems in the range 0 ≤ x ≤1 are studied by mean field theory and high-temperature series expansions. The nearest neighbouring and the next-neighbouring superexchange interactions J1 （x） and J2（x） are evaluated for these systems in the range 0 ≤ x ≤ 1, by using the first theory. The intra-planar and the inter-planar interactions and the exchange energy are deduced. The second theory is applied in the spinel GeNi2-2xCo2O4 systems, combined with the Padé approximants method, to determine the magnetic phase diagrams （TN versus dilution x） in the range 0 ≤ x ≤1. The obtained theoretical results are in agreement with experimental data obtained by magnetic measurements. The critical exponents associated with the magnetic susceptibility γ and the correlation lengths u are deduced.展开更多
The effect of Zn doping on the magnetic properties of CdCr2S4 systems is studied by mean field theory and high-temperature series expansion （HTSE）. The nearest neighbouring and the next-neighbouring super-exchange i...The effect of Zn doping on the magnetic properties of CdCr2S4 systems is studied by mean field theory and high-temperature series expansion （HTSE）. The nearest neighbouring and the next-neighbouring super-exchange interactions Jl（x） and J2（x） are evaluated for the spinel system Zn, Cd1-xCr2S4 in the range 0 〈 x 〈 1. The intra-planar and the inter-planar interactions are deduced. The HTSE combined with the Padd approximant method （PA） is applied to the spinel system ZnxCdl-,Cr2S4. The magnetic phase diagram, i.e. Tc versus dilution x, is obtained. The critical exponents associated with the magnetic susceptibility 7 and the correlation length u are deduced. The obtained theoretical results are in agreement with the experimental data obtained by magnetic measurements.展开更多
文摘The magnetic properties of spinel GeNi2-2x Co2x O4 systems in the range 0 ≤ x ≤1 are studied by mean field theory and high-temperature series expansions. The nearest neighbouring and the next-neighbouring superexchange interactions J1 （x） and J2（x） are evaluated for these systems in the range 0 ≤ x ≤ 1, by using the first theory. The intra-planar and the inter-planar interactions and the exchange energy are deduced. The second theory is applied in the spinel GeNi2-2xCo2O4 systems, combined with the Padé approximants method, to determine the magnetic phase diagrams （TN versus dilution x） in the range 0 ≤ x ≤1. The obtained theoretical results are in agreement with experimental data obtained by magnetic measurements. The critical exponents associated with the magnetic susceptibility γ and the correlation lengths u are deduced.
文摘The effect of Zn doping on the magnetic properties of CdCr2S4 systems is studied by mean field theory and high-temperature series expansion （HTSE）. The nearest neighbouring and the next-neighbouring super-exchange interactions Jl（x） and J2（x） are evaluated for the spinel system Zn, Cd1-xCr2S4 in the range 0 〈 x 〈 1. The intra-planar and the inter-planar interactions are deduced. The HTSE combined with the Padd approximant method （PA） is applied to the spinel system ZnxCdl-,Cr2S4. The magnetic phase diagram, i.e. Tc versus dilution x, is obtained. The critical exponents associated with the magnetic susceptibility 7 and the correlation length u are deduced. The obtained theoretical results are in agreement with the experimental data obtained by magnetic measurements.
