The opto-electronic properties of the transition metal dichalcogenides (TMDs) are sensitive to their environment. For example, the presence of graphene in the vicinity of the TMDs modifies their exciton binding energy and the magnitude of the bandgap via external dielectric screening. [more]

Advances in mid and far-infrared THz sources have created a new paradigm in condensed matter physics: ultrafast structural and functional control through direct lattice excitation. Striking changes in magnetism, metallicity, ferroelectricity, and superconductivity, observed experimentally on ultrafast timescales, have been tied to the anharmonic coupling between pumped infrared-active (IR) phonons and Raman-active phonons via the nonlinear phononics effect. [more]

Symmetry and its breaking sit at the core of condensed matter physics research and determine the ordering and unique functionalities of solid-state materials. Ultrashort light pulses from visible to THz wavelength ranges offer the opportunity to probe and control the electronic, phononic, magnetic, and even time ordering in those materials. [more]

Under the Microscope a science communication project dedicated to materials and nano science. Despite the widespread relevance of materials science to everyday life, we feel that dedicated science communication in this area is much rarer than in other fields. [more]

Ultrashort laser pulses can induce coherent phonons, where all atoms in the crystal oscillate in phase. Using ultrafast electron diffraction, we can directly image this joint atomic motion in the time domain. [more]

Microscopic understanding of exciton physics in molecular materials for optoelectronics is a great challenge because of their complexity resulting from strong electron-phonon coupling and perhaps interaction to spin degree of freedom, electron spin-flip of intersystem crossing in molecular optoelectronic materials are strongly connected to molecular geometries in the excited states and vibronic coupling, and singlet fission, ultrafast generation of a correlated triplet pair state from a singlet excited state, is viewed as an extreme example of a concerted process of electron-phonon-spin degrees of freedom. [more]