Theory predicted that the transition between the superconducting and superfluid regimes should be continuous for electrons and holes in solid materials, but recent high magnetic field experiments performed by researchers from Columbia, Harvard and Brown Universities demonstrated the crossover between coupling regimes.
A new class of correlated quasiparticle states discovered in a multi-valley semiconductor using optical absorption measurements in pulsed magnetic fields. This new type of multi-particle state results when excitons interact simultaneously with multiple electron reservoirs that are quantum-mechanically distinguishable by virtue of having different spin and/or valley quantum numbers.
Gallium nitride (GaN) and Niobium nitride (NbN) are widely used in today's technologies: GaN is used to make blue LEDs and high-frequency transistors while NbN is used to make infrared light detectors. This experiment explores whether a nitride-based device may be relevant for quantum technologies of the future.
This highlight reports on the still poorly understood transition to an electron crystalline state (the Wigner crystal) in a two-dimensional system at extremely low densities, observable at low temperatures as a function of magnetic field. This experiment finds a surprising stabilization of the Wigner crystal arising from magnetic-field-induced spin alignment. Such electrically-delicate samples require the ultra-low-noise environment and experimental techniques available at the High B/T facility.
Interactions between electrons underpin some of the most interesting – and useful -- effects in materials science and condensed-matter physics. This work demonstrates that, in the new family of so-called "monolayer semiconductors" that are only one atomic layer thick, electron-electron interactions can lead to the sudden and spontaneous formation of a magnetized state, analogous to the appearance of magnetism in conventional materials like iron.
Topology, screws, spin and hedgehogs are words not normally found in the same scientific article but with the discovery of Weyl fermions in thin tellurine films they actually belong together. The work in this highlight describes how Qui et. al. used the unique properties of tellurine and high magnetic fields to identify the existence of Weyl fermions in a semiconductor. This discovery opens a new window into the intriguing world to topological materials.
A new study reveals a suite of quantum Hall states that have not been seen previously, shedding new light on the nature of electron interactions in quantum systems and establishing a potential new platform for future quantum computers.
Scientists revealed previously unobserved and unexpected FQH states in monolayer graphene that raise new questions regarding the interaction between electrons in these states.
In the 14 years since its discovery, graphene has amazed scientists around the world with both the ground-breaking physics and technological potential it displays. Recently, scientists from Penn State University added to graphene's gallery of impressive scientific achievements and constructed a map that will aid future exploration of this material. This work is emblematic of the large number of university-based materials research efforts that use the MagLab to explore the frontiers of science.
Decades ago a mechanism was proposed that described a quantum phase transition to an insulating ground state from a semi-metal (excitonic insulator, or EI) using very similar mechanics to those found in the BCS description of superconductivity. The discovery of this transition to an EI in InAs/GaSb quantum wells is striking not only for the long-sought experimental realization of important physics, but also the presence of recently proposed topological behavior.