J. A. Mydosh

Suppressed reflectivity due to spin-controlled localization in a magnetic semiconductor

The narrow gap semiconductor FeSi owes its strong paramagnetism to electron-correlation effects. Partial Co substitution for Fe produces a spin-polarized doped semiconductor. The spin polarization causes suppression of the metallic reflectivity and increased scattering of charge carriers, in contrast to what happens in other magnetic semiconductors, where magnetic order reduces the scattering. The loss of metallicity continues progressively even into the fully polarized state, and entails as much as a 25% reduction in average mean-free path. We attribute the observed effect to a deepening of the potential wells presented by the randomly distributed Co atoms to the majority spin carriers. This mechanism inverts the sequence of steps for dealing with disorder and interactions from that in the classic Altshuler Aronov approach-where disorder amplifies the Coulomb interaction between carriers-in that here, the Coulomb interaction leads to spin polarization which in turn amplifies the disorder-induced scattering.

Epitaxy, stoichiometry, and magnetic properties of Gd-doped EuO films on YSZ (001)

We have succeeded in preparing high-quality Gd-doped single-crystalline EuO films. Using Eu-distillation-assisted molecular beam epitaxy and a systematic variation in the Gd and oxygen deposition rates, we have been able to observe sustained layer-by-layer epitaxial growth on yttria-stabilized cubic zirconia (001). The presence of Gd helps to stabilize the layer-by-layer growth mode. We used soft x-ray absorption spectroscopy at the Eu and Gd

Hysteresis effects in the phase diagram of multiferroic GdMnO 3

{M}_{4,5}

Anomalous thermal expansion and strong damping of the thermal conductivity of NdMnO3 and TbMnO3 due to 4f crystal-field excitations

edges to confirm the absence of

Pressure dependence of the magnetization of U Ru 2 Si 2

{text{Eu}}^{3+}

Mott-Hubbard versus charge-transfer behavior in LaSrMnO4 studied via optical conductivity

contaminants and to determine the actual Gd concentration. The distillation process ensures the absence of oxygen vacancies in the films. From magnetization measurements we found the Curie temperature to increase smoothly as a function of doping from 70 K up to a maximum of 125 K. A threshold behavior was not observed for concentrations as low as 0.2%.

Evidence for strongly coupled charge-density-wave ordering in three-dimensional R 5 Ir 4 Si 10 compounds from optical measurements

We present high-resolution thermal expansion

Insulator to semiconductor transition and magnetic properties of the one-dimensional S=(1/2) system In{sub 2}VO{sub 5}

ensuremath{alpha}(T)

Interplay between structure, transport and magnetism in the frustrated S = 1/2 system In2VO5

and magnetostriction

Magnetothermal evidence of a partial gap at the Fermi surface of UPt2Si2

mathrm{ensuremath{Delta}}L(H)∕L