Let’s Talk: Learning to Communicate Well in Emergency Online Learning

In this article, we use the lens of Tinto’s (1987) separation and transition phases to reflect on lessons learned when moving classes with oral communication components from in-person to online. We believe that being mindful and intentional in how we include oral communication instruction, opportunities for improvement, and incorporating feedback can positively impact retention and persistence of students. First, we describe the timelines of events, then we connect Tinto’s essential features of effective retention programs to oral communication pedagogy, and finally offer resources and strategies for incorporating oral communication into courses

Electroweak Contributions to Squark Pair Production at the LHC

In this paper we compute electroweak contributions to the production of squark pairs at hadron colliders. These include the exchange of electroweak gauge bosons in the s-channel as well as electroweak gaugino exchange in the t- and/or u-channel. In many cases these can interfere with the dominant QCD contributions. As a result, we find sizable contributions to the production of two SU(2) doublet squarks. At the LHC, they amount to 10 to 20% for typical mSUGRA (or CMSSM) scenarios, but in more general scenarios they can vary between -40 and +55%, depending on size and sign of the SU(2) gaugino mass. The electroweak contribution to the total squark pair production rate at the LHC is about 3.5 times smaller.Comment: 28 pages, 9 figure

Graphene as an electronic membrane

Experiments are finally revealing intricate facts about graphene which go beyond the ideal picture of relativistic Dirac fermions in pristine two dimensional (2D) space, two years after its first isolation. While observations of rippling added another dimension to the richness of the physics of graphene, scanning single electron transistor images displayed prevalent charge inhomogeneity. The importance of understanding these non-ideal aspects cannot be overstated both from the fundamental research interest since graphene is a unique arena for their interplay, and from the device applications interest since the quality control is a key to applications. We investigate the membrane aspect of graphene and its impact on the electronic properties. We show that curvature generates spatially varying electrochemical potential. Further we show that the charge inhomogeneity in turn stabilizes ripple formation.Comment: 6 pages, 11 figures. Updated version with new results about the re-hybridization of the electronic orbitals due to rippling of the graphene sheet. The re-hybridization adds the next-to-nearest neighbor hopping effect discussed in the previous version. New reference to recent STM experiments that give support to our theor

A Hierarchically-Organized Phase Diagram near a Quantum Critical Point in URu2Si2

A comprehensive transport study, as a function of both temperature and magnetic field in continuous magnetic fields up to 45 T reveals that URu2Si2 possesses all the essential hallmarks of quantum criticality at temperatures above 5.5 K and fields around 38 T, but then collapses into multiple low temperature phases in a hierarchically-organized phase diagram as the temperature is reduced. Although certain generic features of the phase diagram are very similar to those in the cuprates and heavy fermion superconductors, the existence of multiple ordered hysteretic phases near the field-tuned quantum critical point is presently unique to URu2Si2. This finding suggests the existence of many competing order parameters separated by small energy difference in URu2Si2.Comment: 6 pages, twocolum texts, 3 coloured figure included, submitted to PR

Phonon Thermal Transport of URu2Si2: Broken Translational Symmetry and Strong-Coupling of the Hidden Order to the Lattice

A dramatic increase in the total thermal conductivity (k) is observed in the Hidden Order (HO) state of single crystal URu2Si2. Through measurements of the thermal Hall conductivity, we explicitly show that the electronic contribution to k is extremely small, so that this large increase in k is dominated by phonon conduction. An itinerant BCS/mean-field model describes this behavior well: the increase in kappa is associated with the opening of a large energy gap at the Fermi Surface, thereby decreasing electron-phonon scattering. Our analysis implies that the Hidden Order parameter is strongly coupled to the lattice, suggestive of a broken symmetry involving charge degrees of freedom.Comment: 17 pages including figures, updated author institutions and acknowledgement

Pressure dependence of the magnetization of URu2Si2

The ground state of URu2Si2 changes from so-called hidden order (HO) to large-moment antiferromagnetism (LMAF) upon applying hydrostatic pressure in excess of 14 kbar. We report the dc-magnetization M(B,T,p) of URu2Si2 for magnetic fields B up to 12 T, temperatures T in the range 2 to 100 K, and pressure p up to 17 kbar. Remarkably, characteristic scales such as the coherence temperature T*, the transition temperature T0, and the anisotropy in the magnetization depend only weakly on the applied pressure. However, the discontinuity in dM/dT at T0, which measures the magnetocaloric effect, decreases nearly 50 % upon applying 17 kbar for M and B parallel to the tetragonal c-axis, while it increases 15-fold for the a-axis. Our findings suggest that the HO and LMAF phases have an astonishing degree of similarity in their physical properties, but a key difference is the magnetocaloric effect near T0 in the basal plane

Ferromagnetism in the Mott insulator Ba2NaOsO6

Results are presented of single crystal structural, thermodynamic, and reflectivity measurements of the double-perovskite Ba2NaOsO6. These characterize the material as a 5d^1 ferromagnetic Mott insulator with an ordered moment of ~0.2 Bohr magnetons per formula unit and TC = 6.8(3) K. The magnetic entropy associated with this phase transition is close to Rln2, indicating that the quartet groundstate anticipated from consideration of the crystal structure is split, consistent with a scenario in which the ferromagnetism is associated with orbital ordering.Comment: 5 pages, 5 figures, added reference

Charge-density Waves Survive the Pauli Paramagnetic Limit

Measurements of the resistance of single crystals of (Per)$_2$Au(mnt)$_2$ have been made at magnetic fields $B$ of up to 45 T, exceeding the Pauli paramagnetic limit of $B_{\rm P}\approx 37$ T. The continued presence of non-linear charge-density wave electrodynamics at $B \geq 37$ T unambiguously establishes the survival of the charge-density wave state above the Pauli paramagnetic limit, and the likely emergence of an inhomogeneous phase analogous to that anticipated to occur in superconductors.Comment: 4 pages, three figure

Competing types of quantum oscillations in the 2D organic conductor (BEDT-TTF)8Hg4Cl12(C6H5Cl)2

Interlayer magnetoconductance of the quasi-two dimensional organic metal (BEDT-TTF)8Hg4Cl12(C6H5Cl)2 has been investigated in pulsed magnetic fields extending up to 36 T and in the temperature range from 1.6 to 15 K. A complex oscillatory spectrum, built on linear combinations of three basic frequencies only is observed. These basic frequencies arise from the compensated closed hole and electron orbits and from the two orbits located in between. The field and temperature dependencies of the amplitude of the various oscillation series are studied within the framework of the coupled orbits model of Falicov and Stachowiak. This analysis reveals that these series result from the contribution of either conventional Shubnikov-de Haas effect (SdH) or quantum interference (QI), both of them being induced by magnetic breakthrough. Nevertheless, discrepancies between experimental and calculated parameters indicate that these phenomena alone cannot account for all of the data. Due to its low effective mass, one of the QI oscillation series - which corresponds to the whole first Brillouin zone area - is clearly observed up to 13 K.Comment: 8 pages, 8 figures. To be published in Phys. Rev.

Irreversible dynamics of the phase boundary in U(Ru0.9)Rh0.04)2Si2 and implications for ordering

We report measurements and analysis of the specific heat and magnetocaloric effect at the phase boundary into the single magnetic field-induced phase (phase II) of U(Ru{0.96}Rh{0.04})2Si2, which yield striking similarities to the valence transition of Yb{1-x}YxInCu4. To explain these similarities, we propose a bootstrap mechanism by which a structural distortion causes an electric quadrupolar order parameter within phase II to become coupled to the 5f-electron hybridization, giving rise to a valence change at the transition.Comment: 4 pages including 4 figure