STM 1 Determination of phonon modes in PbSe Reconstructed surface of KV<sub>3</sub>Sb<sub>5</sub> STM 2 The Group!

Recent News

Davide’s Defense

Congratulations to Davide Iaia on completing his PhD Defense, Scanning Tunneling Microscopy and Spectroscopy Study of Phase Transition and Topology in Layered Transition Metal Dichalcogenides!

2020 Awards

Anuva has won a PPG-MRL Fellowship for the 2020-2021 academic year; congratulations to Anuva! Guannan has won the Scott Anderson Outstanding Graduate Assistant Award for 2020 from the UIUC Dept. of Physics; congratulations, Guannan! Undergraduates Zhuozhen Cai and Will Jing have also received Summer 2020 research awards. Zhuozhen received a 2020 Lorella M. Jones Undergraduate Summer Research Award and LAS James Scholar Preble Research Fellowship; Will was awarded a Research Support Grant (RSG) sponsored by the Office of Undergraduate Research (OUR)! And, Rachel Birchmier has received a prestigious NDSEG Fellowship from the US Department of Defense for 2020! Read the Blog for more news from the Madhavan Lab.

Latest Research

Signatures of Chiral Spin-Triplet Topological Superconductivity

<center>Chiral In-Gap States in UTe2</center>
Chiral In-Gap States in UTe2

Nature 579, 523-527 (2020)

Materials with the potential for harboring unconventional spin-triplet pairing superconductivity have attracted significant attention in the condensed matter physics community. Until now, extremely low critical temperatures and superconducting phases buried within a ferromagnetic phase or only appearing at high pressures have hampered efforts to find such materials. However, with a transition temperature of 1.6 K having been recently discovered in the heavy fermion compound UTe2, the material has presented a new opportunity to investigate possible spin-triplet pairing. Using scanning tunneling microscopy and spectroscopy, our group has found chiral in-gap states in UTe2, providing direct experimental evidence for chiral spin-triplet topological superconductivity.

Majorana’s on the Move


Science 367, 104-108 (2020)
Read the Science Perspective!

Majorana particles, excitations which are their own anti-particle, have gained much attention for their potential in topological quantum computing. Previously realized as 0D excitations in superconducting vortices, they have also been theorized to exist in 1D inside of topological supercoductors. Recently we have observed the signature of 1D Majorana modes at domain walls in FeSe0.45Te0.55, where a π phase shift in the superconducting order parameter hosts these exotic states.

Electrons Stuck in 1D

<center>Evidence for Wigner Crystallization in TaS2</center>
Evidence for Wigner Crystallization in TaS2

In the material TaS2, a Mott Insulating phase is closely related to a coexisting “Star of David” charge density wave. On a specific charge density wave domain wall, the local electronic potential well is strong enough to shift the lower Hubbard band all the way to the Fermi energy. The strong electronic correlations in this material combined with the low electron density along the domain wall present the perfect conditions for Wigner crystallization. When measuring the differential conductance, a proxy for the local density of states, we see zigzag patterns predicted for Wigner crystallization in 1D. Combined with noise measurements, this provides the first experimental observation of a 1D Wigner crystal within a Mott Insulator.

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