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Handed light throws electronic curve balls in quantum flatland [innovations-report.com]:

In the new work, Michael Schüler, formerly a postdoctoral researcher at the University of Fribourg, Switzerland and now based at SLAC and Stanford University, USA, together with Umberto De Giovannini from the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg and colleagues suggest adding a twist to conventional photoelectron spectroscopy. The laser light has an additional property, namely polarization.

Circularly polarized light has a handedness -- right-handed or left-handed -- also known as chirality, which means that the electromagnetic field of the light wave rotates clockwise or counter-clockwise as the light moves through space. In their numerical simulations, the researchers showed that the photoelectron signal looks different for right-handed versus left-handed light. Moreover, they showed that this difference is directly tied to the Berry curvature of the electronic wavefunctions inside the material.

"We show that one can tease out more information about the electrons than merely their energy and momentum, which are usually mapped out", explains Schüler. "We have calculated the expected signals for some typical and important atomically flat materials, which are now at the forefront of quantum materials science and seen as potential candidates for quantum technologies", adds De Giovannini.

"It is surprising how well this method works and we expect that experimental advances in these imaging techniques will enhance our knowledge about topological properties in the very near future." This proposal could lead to high-precision imaging diagnostics of novel materials and pave the way for future quantum technologies employing the Berry curvature of matter.

The researchers also expect that the technique can be generalized to the ultrafast dynamical regime. "We are at the beginning of a nonequilibrium revolution,"adds Philipp Werner, a physics professor in Fribourg. "There are numerous theory proposals and some very promising first experimental demonstrations of topological properties in materials that are changed on femtosecond time scales by the application of ultrashort laser pulses.”

Angel Rubio, theory director at MPSD, predicts: "Our method of imaging topological properties can be directly generalized to this time domain, and will allow important insights into how light can be used to create properties on demand in quantum materials."

Wissenschaftliche Ansprechpartner:

Dr Michael Schüler, lead author: schuelem@stanford.edu
Dr Michael Sentef, co-author: michael.sentef@mpsd.mpg.de

Originalpublikation:

https://advances.sciencemag.org/content/6/9/eaay2730.full [sciencemag.org]

Weitere Informationen:

https://www.mpsd.mpg.de/426134/2020-02-sentef-berrycurvature [mpsd.mpg.de]

Jenny Witt | Max-Planck-Institut für Struktur und Dynamik der Materie

Further reports about: Berry curvature [innovations-report.com] Dynamik [innovations-report.com] Electrons [innovations-report.com] Materie [innovations-report.com] Max-Planck-Institut [innovations-report.com] phenomenon [innovations-report.com] photoelectron spectroscopy [innovations-report.com] spectroscopy [innovations-report.com]

Original Submission