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Integrating a phase transition material with two-dimensional semiconductors can provide a route towards tunable opto-electronic metamaterials. Here, we integrate monolayer transition metal dichalcogenides with vanadium dioxide (VO2) thin films grown via molecular beam epitaxy to form a 2D/3D heterostructure. Vanadium dioxide undergoes an insulator-to-metal transition at 60–70 °C, which changes the band alignment between MoS2 and VO2 from a semiconductor–insulator junction to a semiconductor–metal junction. By switching VO2 between insulating and metallic phases, the modulation of photoluminescence emission in the 2D semiconductors was observed. This study demonstrates the feasibility to combine TMDs and functional oxides to create unconventional hybrid optoelectronic properties derived from 2D semiconductors that are linked to functional properties of oxides through proximity coupling.

Bulk nanocomposite magnets with enhanced magnetic properties and (0 0 l) crystallographic texture for the (Nd,Pr)2Fe14B hard magnetic phase were prepared by thermo-mechanical process of Nd3.6Pr5.4Fe83Co3B5 ribbons. Ribbons with different microstructures, i.e. an amorphous state and amorphous matrix with a few α-(Fe,Co) nanocrystals, were employed in this study. Optimum magnetic properties were obtained in the magnets made by the hot deformation of the ribbons with nanocrystals in the amorphous matrix; the maximum energy product (BH)max = 118.6 kJ m−3. The magnets made from ribbons with a fully amorphous structure showed the largest magnetic anisotropy, and the values of (BH)max measured parallel (∥) and perpendicular (⊥) to the stress direction were ∼102.7 kJ m−3 and 79.6 kJ m−3, respectively. This study is of importance for the development of bulk anisotropic nanocomposite magnets with enhanced magnetic properties.

Thermodynamic fluctuation among many electronic states in systems with ‘itinerant-electron’ magnetism is addressed with a first-principles formulation of the Helmholtz energy. The Ce γ ‐α phase transition is used as an illustrative case. The kB ln(2J + 1) form for the magnetic entropy that is commonly found in the literature is replaced with an expression that is derived from configurational fluctuations among nonmagnetic, ferromagnetic, and antiferromagnetic electronic states. Predicted first- and second-order magnetic phase transitions are in close accord with experiment. The mixture of states leads to a Schottky anomaly in the Ce specific heat. (Some figures in this article are in colour only in the electronic version)

Elasticity tensor components, Cij, the crystallographic dependence of Poisson's ratio, the phase stability, and vibrational spectra are computed for nonmagnetic and magnetic CeMg (1:1 Ce:Mg) structures using density functional theory. Results from both the generalized gradient approximation (GGA), and the GGA+U, based upon an effective on-site Coulomb potential, Ueff, are investigated. The GGA low energy structure, with wavevector along [110], disagrees with experiment, while the [100] structure from experiment is predicted as the 0?K structure in the GGA+U. Accurate estimation of the 20?K N?el temperature can only be achieved with small Ueff, which suggests that CeMg is not a strongly correlated system. For all CeMg structures investigated, we find C11?C44; this is consistent with the near equivalency of transverse and longitudinal sound speeds. The origin of this behavior is the negative stretching force constants for the interaction between the second-?and third-nearest-neighbor Mg and Ce ions, respectively. Results are compared with neutron scattering experiments at 30 and 110?K.