Researchers at the University of Stuttgart have developed a groundbreaking quantum microscopy method that allows for the visualization of electron movements in slow motion, a feat previously unachievable. Prof. Sebastian Loth, managing director of the Institute for Functional Matter and Quantum Technologies (FMQ), explains that this innovation addresses long-standing questions about electron behavior in solids, with significant implications for developing new materials.
In conventional materials like metals, insulators, and semiconductors, atomic-level changes do not alter macroscopic properties. However, advanced materials produced in labs show dramatic property shifts, such as turning from insulators to superconductors, with minimal atomic modifications. These changes occur within picoseconds, directly affecting electron movement at the atomic scale.
THE IMAGING TIP OF THE TIME-RESOLVING SCANNING TUNNELING MICROSCOPE CAPTURES THE COLLECTIVE ELECTRON MOTION IN MATERIALS THROUGH ULTRAFAST TERAHERTZ PULSES. PHOTO CREDIT: © SHAOXIANG SHENG, UNIVERSITY OF STUTTGART(FMQ)
Loth’s team has successfully observed these rapid changes by applying a one-picosecond electrical pulse to a niobium and selenium material, studying the collective motion of electrons in a charge density wave. They discovered how single impurities can disrupt this collective movement, sending nanometer-sized distortions through the electron collective. This research builds on previous work at the Max Planck Institutes in Stuttgart and Hamburg.
Understanding how electron movement is halted by impurities could enable the targeted development of materials with specific properties, beneficial for creating ultra-fast switching materials for sensors or electronic components. Loth emphasizes the potential of atomic-level design to impact macroscopic material properties.
The innovative microscopy method combines a scanning tunneling microscope, which offers atomic-level resolution, with ultrafast pump-probe spectroscopy to achieve both high spatial and temporal resolution. The experimental setup is highly sensitive, requiring shielding from vibrations, noise, and environmental fluctuations to measure extremely weak signals. The team’s optimized microscope can repeat experiments 41 million times per second, ensuring high signal quality and making them pioneers in this field.
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