Leipzig physicists show that light can generate electricity even in translucent materials

Likun Shi (left) and Inti Sodemann (right) at their institute. Photo: Sebastian
Likun Shi (left) and Inti Sodemann (right) at their institute. Photo: Sebastian Mantilla Serrano/Leipzig University
News from

Some materials are transparent to light of a certain frequency. When such light is shone on them, electrical currents can still be generated, contrary to previous assumptions. Scientists from Leipzig University and Nanyang Technological University in Singapore have managed to prove this. "This opens new paradigms for constructing opto-electronic and photovoltaic devices, such as light amplifiers, sensors and solar cells," says Inti Sodemann Villadiego, Professor at the Institute of Theoretical Physics at Leipzig University. The scientists have published their findings in the journal Physical Review Letters.

"It is possible to drive electric currents by light even when the material has a vanishingly small absorption of such light. This is an important new insight," adds his colleague Li-kun Shi.

Inti Sodemann Villadiego and his colleagues investigated what are known as "Floquet Fermi liquid" states. A Fermi liquid is a special state of many quantum mechanical particles with properties that can be very different from those of ordinary classical liquids such as water at ambient temperature. Fermi liquids can arise in a wide variety of situations, from common materials such as the electrical fluid of electrons in metals like gold or silver, to more exotic situations such as the fluid of Helium-3 atoms at low temperatures. They can display "spectacular properties", such as becoming superconductors of electricity at low temperatures. The "Floquet Fermi liquid" is a variant of this state realised when the particles of the fluid are periodically shaken, such as what happens to electrons in metals when they are illuminated by ideally periodic light.

"In our publication, we explain several properties of these fluid states," says Professor Sodemann Villadiego. "To study them, we had to develop detailed theoretical models of complex states of electrons shaken by light, which is far from easy." After the publication in Physical Review Letters, the four researchers - including Sodemann Villadiego from Leipzig University and his colleague Li-kun Shi - received a special honour: a separate article highlighting their research was published by the popular physics news website Phys.org.

Paper in Physical Review Letters: "Floquet Fermi Liquid" , DOI: 10.1103/PhysRevLett.132.146402