Large Anomalous Hall Effect in a Half-Heusler Antiferromagnet

  • By Aude Marjolin
  • 20 July 2016

Recently a team of researchers from MIT, the NIST Center for Neutron Research (NCNR), Carnegie Mellon University, and the Beijing Institute of Technology have experimentally demonstrated a "hybrid material" solution to this problem. They studied a compound of three elements, gadolinium, platinum and bismuth, known together as a ternary compound. In their compound, gadolinium supplies the magnetic order while the platinum-bismuth components support a topological electronic structure. These two components acting in concert make a correlated material that is more than the sum of its parts, showing quantum mechanical corrections to electrical properties at an unprecedented scale. Their results were reported July 18 in Nature Physics.

The theoretical aspect of the collaborative effort was with professors Di Xiao of Carnegie Mellon University and Wanxiang Feng of Beijing Institute of Technology, who provided first principles electronic structure calculations based on the experimental data taken at MIT, NCNR, and the NHMFL to determine the underlying electronic character of this new materials system.

Quantum-Engineered Catalysts that Turn Excess Atmospheric CO2 into Liquid Fuel

  • By Aude Marjolin
  • 8 December 2015

PQI faculty Karl Johnson and his team recently identified the two main factors for determining the optimal catalyst for turning atmospheric CO2 into liquid fuel. The results of the study, which appeared in the journal ACS Catalysis, will streamline the search for an inexpensive yet highly effective new catalyst.

Imagine a power plant that takes the excess carbon dioxide (CO2) put in the atmosphere by burning fossil fuels and converts it back into fuel. Now imagine that power plant uses only a little water and the energy in sunlight to operate. The power plant wouldn't burn fossil fuels and would actually reduce the amount of CO2 in the atmosphere during the manufacturing process. For millions of years, actual plants have been using water, sunlight, and CO2 to create sugars that allow them to grow. Scientists around the globe are now adopting their energy-producing behavior.


Swing-Dancing Electron Pairs

  • By Aude Marjolin
  • 13 May 2015

A research team led by PQI faculty Jeremy Levy has discovered electrons that can "swing dance". This unique electronic behavior can potentially lead to new families of quantum devices.

Superconductors, materials that permit electrical current to flow without energy loss, form the basis for magnetic resonance imaging devices as well as emergingtechnologies such as quantum computers. At the heart of all superconductors is the bunching of electrons into pairs.

The work, done in collaboration with researchers from the University of Wisconsin-Madison and the U.S. Naval Research Laboratory, was published May 14 in the journal Nature.

Breakthrough in Particle Control Creates Special Half-Vortex Rotation

  • By Aude Marjolin
  • 3 March 2015

A breakthrough in the control of a type of particle known as the polariton has created a highly specialized form of rotation. 

PQI faculty Andrew Daley and David Snoke and their colleages at Princeton University conducted a test in which they were able to arrange the particles into a 'ring geometry' form in a solid-state environment. The result was a half-vortex in a 'quantized rotation' form.


A 'Quantum Repository' to Make Learning Chemistry Easier

  • By Aude Marjolin
  • 19 November 2014

Remember constructing ball-and-stick models of molecules in your high school or college chemistry classes? Well, that might soon be a thing of the past for Pitt students looking to get a three-dimensional understanding of molecular structures.

PQI faculty Geoffrey Hutchison and Daniel Lambrecht recently received a 2014 Camille and Henry Dreyfus Special Grant Program in the Chemical Sciences award for their project, "Creating an Open Quantum Chemistry Repository." This effort aims to create an open mobile-ready, web-based database of accurate, quantum calculations of molecules. The "Pitt Quantum Repository" will consist at first of 50,000 to 100,000 molecules and quantum chemical data. The database will grow over time to include more molecules and more computed properties.

New Photonic Device for Use in Harsh Environments

  • By Aude Marjolin
  • 26 June 2014

By fusing together the concepts of active fiber sensors and high-temperature fiber sensors, a team of researchers at the University of Pittsburgh led by PQI faculty Kevin Chen has created an all-optical high-temperature sensor for gas flow measurements that operates at record-setting temperatures above 800 degrees Celsius. This technology is expected to find industrial sensing applications in harsh environments ranging from deep geothermal drill cores to the interiors of nuclear reactors to the cold vacuum of space missions, and it may eventually be extended to many others.

The team describes their all-optical approach in a paper published in Optics Letters.

First Detection of a Fundamental Particle of Light-Matter Interaction in Metals: the Exciton

  • By Aude Marjolin
  • 1 June 2014

PQI faculty Hrvoje Petek and Sean Garrett-Roe have become the first to detect a fundamental particle of light-matter interaction in metals, the exciton. The team has published its work in the June 2014 online issue of Nature Physics.

Mankind has used reflection of light from a metal mirror on a daily basis for millennia, but the quantum mechanical magic behind this familiar phenomenon is only now being uncovered.

Massive Dirac Fermions and Hofstadter Butterfly in a van der Waals Heterostructure

  • By Aude Marjolin
  • 21 June 2013

The remarkable transport properties of graphene, such as the high electron mobility, make it a promising material for electronics. However, unlike semiconductors such as silicon, graphene's electronic structure lacks a band gap, and a transistor made out of graphene would not have an “off” state. Ben Hunt and his colleagues modulated the electronic properties of graphene by building a heterostructure consisting of a graphene flake resting on hexagonal boron nitride (hBN), which has the same honeycomb structure as graphene, but consists of alternating boron and nitrogen atoms instead of carbons. The natural mismatch between the graphene and hBN lattices led to a moire pattern with a large wavelength, causing the opening of a band gap, the formation of an elusive fractional quantum Hall state, and, at high magnetic fields, a fractal phenomenon in the electronic structure called the Hofstadter butterfly.

Quantum-Engineered Nanoscale Alloys So Bright They Could Have Potential Medical Applications

  • By Aude Marjolin
  • 14 May 2013

Alloys like bronze and steel have been transformational for centuries, yielding top-of-the-line machines necessary for industry. As scientists move toward nanotechnology, however, the focus has shifted toward creating alloys at the nanometer scale—producing materials with properties unlike their predecessors.

Now, researchers led by PQI faculty Jill Millstone demonstrate that nanometer-scale alloys possess the ability to emit light so bright they could have potential applications in medicine. The findings have been published in the Journal of the American Chemical Society.

Connecting the (Quantum) Dots: Spin Technique Moves Researchers Closer to Creating First Viable High-Speed Quantum Computer

  • By Aude Marjolin
  • 26 February 2013

Recent research offers a new spin on using nanoscale semiconductor structures to build faster computers and electronics. Literally.

Researchers at PQI and Delft University of Technology reveal in the Nature Nanotechnology a new method that better preserves the units necessary to power lightning-fast electronics, known as qubits (pronounced CUE-bits). Hole spins, rather than electron spins, can keep quantum bits in the same physical state up to 10 times longer than before, the report finds.