Magneto-optical resonance in ferromagnetic gadolinium

The optical constants n and k of ferromagnetic and paramagnetic gadolinium have been measured, at various temperatures, from polarimetric measurements, in the low energy range 0.5 to 1.5 eV. For the ferromagnetic state, evidence of extra-optical conductivity is found near 0.69 eV and attributed to magnetic ordering. It confirms Miwa and Mackintosh predictions, assuming that new energy gaps are introduced in the conduction band through the s-f exchange interaction. From the experimental determination of the energy gap resulting from a splitting of the conduction band between spin up and spin down bands, we have deduced the effective s-f exchange energy J(q) = 1.58 × 10^-13 erg.     

Study of structural and electronic transport properties of Ce-doped LaMnO3

The structural and electronic transport properties of La_1−x Ce _x MnO₃ (x=0.0–1.0) have been studied. All the samples exhibit orthorhombic crystal symmetry and the unit cell volume decreases with Ce doping. They also make a metal-insulator transition (MIT) and transition temperature increases with increase in Ce concentration up to 50% doping. The system La_0.5Ce_0.5MnO₃ also exhibits MIT instead of charge-ordered state as observed in the hole doped systems of the same composition.     

Two connected inverse spectral transforms

We establish a transformation which connects the potentials of the one-dimensional Dirac and Klein-Gordon operators. This transformation links the solutions of the nonlinear evolution equations solvable by means of the two inverse spectral transforms which use the Dirac and Klein-Gordon direct and inverse spectral problems.