Dept Theory

The world is never really at rest. Even in a vacuum near ultracold temperatures where all classical motion should come to a halt, you will find quantum fluctuations. In thin, two-dimensional materials, these include random vibrations that can alter electromagnetic fields – a feature that theorists have long posited could be useful for modifying materials. Angel Rubio, Director of the Theory Department at the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg, has been one of the principal architects of this idea. Together with colleagues Rubio developed the theoretical framework predicting that quantum fluctuations inside cavities could reshape the properties of solids – without any external force. Now, that prediction has been confirmed experimentally for the first time. In a new paper published in Nature, an international team of 33 researchers from 17 institutions – including a large MPSD contingent – demonstrates that quantum fluctuations from the vacuum alone inside atom-thin layers of a 2D material can alter the properties of a nearby crystal. more

Probing the vibration of atoms provides detailed information on local structure and bonding that define material properties. Tip-enhanced Raman spectroscopy (TERS) offers extremely high resolution to probe such vibrations. Krystof Brezina and Mariana Rossi from the MPI for the Structure and Dynamics of Matter (MPSD), and Yair Litman from the MPI for Polymer Research (MPIP), have demonstrated that realistic, first-principles simulations are essential for interpreting TERS images of molecules and materials on surfaces. Their approach reveals how interactions with metallic substrates reshape vibrational imaging at the nanoscale. The work has now been published in ACS Nano. more

Researchers at ETH Zurich and the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) have shown, for the first time with very high time and spatial resolution, that electrons in certain two-dimensional materials only follow the motion of the atomic nuclei with a delay. This insight could lead to the development of novel electronic devices in the future. more

Researchers at the Max-Planck-Institute for the Structure and Dynamics of Matter (MPSD) and partner institutes have developed a general and experimentally realistic method to create square-lattice moiré materials by twisting two-dimensional semiconductors with rectangular unit cells by 90 degrees. This simple geometric recipe produces moiré patterns with square symmetry and flat, isolated electronic bands that map onto a tunable square-lattice Hubbard model—the theoretical framework underpinning magnetism and high-temperature superconductivity. The approach works across a broad class of materials and offers powerful knobs to explore correlated-electron phases in a clean, gate-tunable platform. more

A joint team of scientists from Cornell University, Stanford University and the Max-Planck-Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg have shown that moiré patterns can move coherently when illuminated with light. Their study reveals ultrafast atomic twisting in 2D materials, overturning the existing view that light only causes random heating of the material. This work opens a new pathway for controlling electronic behavior with light in next-generation opto-electronic devices. This work has now been published in Nature. more