Open Access. Powered by Scholars. Published by Universities.®

Physics Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 6 of 6

Full-Text Articles in Physics

Spin-Imbalance In A 2d Fermi-Hubbard System, Peter T. Brown, Debayan Mitra, Elmer Guardado-Sanchez, Peter Schauß, Stanimir S. Kondov, Ehsan Khatami, Thereza Paiva, Nandini Trivedi, David A. Huse, Waseem S. Bakr Sep 2017

Spin-Imbalance In A 2d Fermi-Hubbard System, Peter T. Brown, Debayan Mitra, Elmer Guardado-Sanchez, Peter Schauß, Stanimir S. Kondov, Ehsan Khatami, Thereza Paiva, Nandini Trivedi, David A. Huse, Waseem S. Bakr

Ehsan Khatami

The interplay of strong interactions and magnetic fields gives rise to unusual forms of superconductivity and magnetism in quantum many-body systems. Here, we present an experimental study of the two-dimensional Fermi-Hubbard model—a paradigm for strongly correlated fermions on a lattice—in the presence of a Zeeman field and varying doping. Using site-resolved measurements, we revealed anisotropic antiferromagnetic correlations, a precursor to long-range canted order. We observed nonmonotonic behavior of the local polarization with doping for strong interactions, which we attribute to the evolution from an antiferromagnetic insulator to a metallic phase. Our results pave the way to experimentally mapping ...


Interplay Of Quantum Size Effect, Anisotropy And Surface Stress Shapes The Instability Of Thin Metal Films, Mikhail Khenner Aug 2017

Interplay Of Quantum Size Effect, Anisotropy And Surface Stress Shapes The Instability Of Thin Metal Films, Mikhail Khenner

Mikhail Khenner

Morphological instability of a planar surface ([111], [011], or [001]) of an ultra-thin metal film is studied in a parameter space formed by three major effects (the quantum size effect, the surface energy anisotropy and the surface stress) that influence a film dewetting. The analysis is based on the extended Mullins equation, where the effects are cast as functions of the film thickness. The formulation of the quantum size effect (Z. Zhang et al., PRL 80, 5381 (1998)) includes the oscillation of the surface energy with thickness caused by electrons confinement. By systematically comparing the effects, their contributions into the ...


Comparing Experts And Novices In Solving Electrical Circuit Problems With The Help Of Eye-Tracking, David Rosengrant, Colin Thomson, Taha Mzoughi Jul 2017

Comparing Experts And Novices In Solving Electrical Circuit Problems With The Help Of Eye-Tracking, David Rosengrant, Colin Thomson, Taha Mzoughi

David Rosengrant

In order to help introductory physics students understand and learn to solve problems with circuits, we must first understand how they differ from experts. This preliminary study focuses on problem-solving dealing with electrical circuits. We investigate difficulties novices have with circuits and compare their work with those of experts. We incorporate the use of an eye-tracker to investigate any possible differences or similarities on how experts and novices solve electrical circuit problems. Our results show similarities in gaze patterns among all subjects on the components of the circuit. We further found that experts would look back at the circuit while ...


Highly Directional Receiver And Source Antennas Using Photonic Band Gap Crystals, Rana Biswas, Gary L. Tuttle, Ekmel Ozbay, Burak Temelkuran, Mihail Sigalas, Kai-Ming Ho Jun 2017

Highly Directional Receiver And Source Antennas Using Photonic Band Gap Crystals, Rana Biswas, Gary L. Tuttle, Ekmel Ozbay, Burak Temelkuran, Mihail Sigalas, Kai-Ming Ho

Gary Tuttle

A directional antenna made with photonic band gap structures has been presented. The directional antenna is formed with two photonic band gap structures oriented back to back and separated from each other by a distance to form a resonant cavity between the photonic band gap structures. An antenna element is placed in the resonant cavity. The resonant frequency of the cavity is tuned by adjusting the distance between the photonic band gap structures. The resonant cavity can be asymmetrical or symmetrical.


Ferromagnetism Of Magnetically Doped Topological Insulators In Crxbi2− Xte3 Thin Films, Yan Ni, Z. Zhang, Ikenna C. Nlebedim, M. Ravi Hadimani, Gary L. Tuttle, David C. Jiles Jun 2017

Ferromagnetism Of Magnetically Doped Topological Insulators In Crxbi2− Xte3 Thin Films, Yan Ni, Z. Zhang, Ikenna C. Nlebedim, M. Ravi Hadimani, Gary L. Tuttle, David C. Jiles

Gary Tuttle

We investigated the effect of magnetic doping on magnetic and transport properties of Bi2Te3thin films. CrxBi2−xTe3 thin films with x = 0.03, 0.14, and 0.29 were grown epitaxially on mica substrate with low surface roughness (∼0.4 nm). It is found that Cr is an electron acceptor in Bi2Te3 and increases the magnetization of CrxBi2−xTe3. When x = 0.14 and 0.29,ferromagnetism appears in CrxBi2−xTe3 thin films, where anomalous Hall effect and weak localization of magnetoconductance were observed. The Curie temperature, coercivity, and remnant Hall resistance of thin films increase with increasing Cr concentration ...


A Period Examination Through Contemporary Energy Analysis Of Kevin Roche’S Fine Arts Center At University Of Massachusetts-Amherst, L Carl Fiocchi Jr May 2017

A Period Examination Through Contemporary Energy Analysis Of Kevin Roche’S Fine Arts Center At University Of Massachusetts-Amherst, L Carl Fiocchi Jr

L. Carl Fiocchi

Studies of buildings belonging to a subset of Modernist architecture, Brutalism, have included discussions pertaining to social and architectural history, critical reception, tectonic form and geometry inspirations, material property selections, period technology limitations, and migration of public perceptions. Evaluations of Brutalist buildings’ energy related performances have been restricted to anecdotal observations with particular focus on the building type’s poor thermal performance, a result of the preferred construction method, i.e. monolithic reinforced concrete used as structure, interior finish and exterior finish. A valid criticism, but one that served to dismiss discussion that the possibility of other positive design strategies ...