0000000000794193
AUTHOR
S. Cojocaru
showing 2 related works from this author
Modification of the Bloch law in ferromagnetic nanostructures
2014
The temperature dependence of magnetization in ferromagnetic nanostructures (e.g., nanoparticles or nanoclusters) is usually analyzed by means of an empirical extension of the Bloch law sufficiently flexible for a good fitting to the observed data and indicates a strong softening of magnetic coupling compared to the bulk material. We analytically derive a microscopic generalization of the Bloch law for the Heisenberg spin model which takes into account the effects of size, shape and various surface boundary conditions. The result establishes explicit connection to the microscopic parameters and differs significantly from the existing description. In particular, we show with a specific examp…
Incoherent midinfrared charge excitation and the high-energy anomaly in the photoemission spectra of cuprates
2007
On the basis of a semi-phenomenological model, it is argued that the high energy anomaly observed in recent photoemission experiments on cuprates is caused by interaction with an overdamped bosonic mode in the mid-infrared region of the spectrum. Analysis of optical conductivity allows to connect this excitation to the incoherent charge response reported for the majority of high Tc materials and some other perovskites. We show that its large damping is an essential feature responsible for the "waterfall" dispersion and linewidth of the spectral weight.