Columbia University Creates Groundbreaking 2D Heavy Fermion Material

Wednesday - January 17 2024, 23:03 UTC - 10 months ago

Columbia University has successfully synthesized the first 2D heavy fermion material, CeSiI, which opens the door for new research into quantum phenomena. The material, composed of cerium, silicon, and iodine, is easier to manipulate and possesses potential 2D quantum properties. Although superconductivity was not achieved, the Roy lab will continue to study CeSiI and its potential applications.

A significant breakthrough in quantum material science has been made by researchers at Columbia University, who have successfully synthesized the first 2D heavy fermion material. The material, named CeSiI, is a layered intermetallic crystal composed of cerium, silicon, and iodine. This groundbreaking achievement was published in a research article on January 17th in the esteemed scientific journal Nature.

Heavy fermion compounds are a class of materials with electrons that are up to 1000 times heavier than usual. These heavy fermions are created when electrons get tangled up with magnetic spins, slowing them down and increasing their effective mass. Scientists believe that these interactions play a crucial role in various quantum phenomena, such as superconductivity, which is the movement of electrical current with zero resistance.

Scientists have been studying heavy fermion compounds for decades, but only in the form of bulky, 3D crystals. The development of CeSiI, a van der Waals crystal that can be peeled into layers just a few atoms thick, allows researchers to explore the properties of heavy fermions in 2D. This is an essential advancement in the field, as many interesting things can happen when you shrink dimensions, as seen in the recent Nobel Prize-winning research on quantum dots.

PhD student Victoria Posey, from the lab of Columbia chemist Xavier Roy, was responsible for synthesizing CeSiI. This is no small feat, as the material is extremely air-sensitive and requires careful preparation for transport. Once Posey successfully prepared the crystal, it was taken to the Scanning Tunneling Microscope (STM) in Abhay Pasupathy's physics lab at Columbia. Using the STM, they observed a particular spectrum signature that is indicative of heavy fermions. To confirm that CeSiI was indeed a heavy fermion material, Posey synthesized an equivalent non-magnetic material and weighed the electrons of both materials via their heat capacities. The electrons of CeSiI were found to be heavier, providing further evidence of its unique properties.

The research team then sent samples of CeSiI to various labs for additional analyses. These included the study of its photoemission spectroscopy at Brookhaven National Laboratory, electron transport measurements at Harvard, and magnetic properties tests at the National High Magnetic Field Laboratory in Florida. Although superconductivity was not achieved, even at very low temperatures, the discovery of CeSiI opens the door for further research into quantum phenomena.

The Roy lab will continue to prepare samples of CeSiI, which are now available for researchers worldwide. The lab will also explore the potential of CeSiI in creating heavy fermion insulators, which could have significant implications for defeating the Coulomb interaction, a force that traditionally repels electrons.