Physical Sciences and Mathematics Commons^™

Similar Ultrafast Dynamics Of Several Dissimilar Dirac And Weyl Semimetals, Christopher P. Weber, Bryan S. Berggren, Madison G. Masten, Thomas C. Ogloza, Skylar Deckoff-Jones, Julien Madéo, Michael K. L. Man, Keshav M. Dani, Lingxiao Zhao, Genfu Chen, Jinyu Liu, Zhiqiang Mao, Leslie M. Schoop, Bettina V. Lotsch, Stuart S. P. Parkin, Mazhar Ali

Physics

Recent years have seen the rapid discovery of solids whose low-energy electrons have a massless, linear dispersion, such as Weyl, line-node, and Dirac semimetals. The remarkable optical properties predicted in these materials show their versatile potential for optoelectronic uses. However, little is known of their response in the picoseconds after absorbing a photon. Here, we measure the ultrafast dynamics of four materials that share non-trivial band structure topology but that differ chemically, structurally, and in their low-energy band structures: ZrSiS, which hosts a Dirac line node and Dirac points; TaAs and NbP, which are Weyl semimetals; and Sr_{1–y …}

L-Edge Spectroscopy Of Dilute, Radiation-Sensitive Systems Using A Transition-Edge-Sensor Array, Charles J. Titus, Michael L. Baker, Sang Jun Lee, Hsiao-Mei Cho, William B. Doriese, Joseph W. Fowler, Kelly Gaffney, Johnathon D. Gard, Gene C. Hilton, Chris Kenney, Jason Knight, Dale Li, Ronald Marks, Michael P. Minitti, Kelsey M. Morgan, Galen C. O'Neil, Carl D. Reintsema, Daniel R. Schmidt, Dimosthenis Sokaras, Daniel S. Swetz, Joel N. Ullom, Tsu-Chien Weng, Christopher Williams, Betty A. Young, Kent D. Irwin, Edward I. Solomon, Dennis Nordlund

Physics

We present X-ray absorption spectroscopy and resonant inelastic X-ray scattering (RIXS) measurements on the iron L-edge of 0.5 mM aqueous ferricyanide. These measurements demonstrate the ability of high-throughput transition-edge-sensor (TES) spectrometers to access the rich soft X-ray (100–2000 eV) spectroscopy regime for dilute and radiation-sensitive samples. Our low-concentration data are in agreement with high-concentration measurements recorded by grating spectrometers. These results show that soft-X-ray RIXS spectroscopy acquired by high-throughput TES spectrometers can be used to study the local electronic structure of dilute metal-centered complexes relevant to biology, chemistry, and catalysis. In particular, TES spectrometers have a unique ability to characterize …

The Santa Clara, 2017-11-16, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2017-11-09, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2017-11-02, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2017-10-26, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2017-10-19, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2017-10-12, Santa Clara University

The Santa Clara

No abstract provided.

The Santa Clara, 2017-10-05, Santa Clara University

The Santa Clara

No abstract provided.

Santa Clara Magazine, Volume 58 Number 4, Fall 2017, Santa Clara University

Santa Clara Magazine

18 - TIME FOR A BIG SHIFT We work and save for decades. And then what? A behavioral finance expert writes about the tough transition many face. By Meir Statman. Illustrations by Hanna Barczyk.

22 - WHAT WE OWE At the very least: stories that capture the contour of a life. A Pulitzer Prize– winning reporter on tales of human strife and resilience. By Tatiana Sanchez ’10.

28 - THE MOST IMPORTANT Lawsuit on the Planet It was first filed against the Obama administration and draws on decades of government records. It seeks no monetary damages. But advocates and critics …

The Santa Clara, 2017-09-28, Santa Clara University

The Santa Clara

No abstract provided.

Ambipolar Spin Diffusion In P-Type Gaas: A Case Where Spin Diffuses More Than Charge, F. Cadiz, V. Notot, J. Filipovic, Christopher P. Weber, L. Martinelli, A.C. H. Rowe, S. Arscott

Physics

We investigate the diffusion of charge and spin at 15 K in p-type GaAs, combining transient-grating and energy-resolved microluminescence measurements to cover a broad range of photoelectron density. At very low optical power, in a unipolar nondegenerate regime, charge and spin diffuse at the same rate, implying that the spin-drag effects are negligible. Upon increasing the photoelectron concentration up to about 1016 cm–3, the charge diffusion constant decreases because of ambipolar electrostatic interactions with the slower-diffusing holes while the spin diffusion constant is reduced only weakly by the ambipolar interaction. A further increase in the excitation power causes increases in …

Santa Clara Magazine, Volume 58 Number 3, August 2017, Santa Clara University

Santa Clara Magazine

3 - PAINT BY NUMBERS By Harold Gutmann and Matt Morgan

4 - SUPERMAN By Sam Farmer

7 - A WILD GENEROSITY By Brian Doyle

Natural Color Symmetry, Frank A. Farris

Mathematics and Computer Science

Existing techniques to create images with color-reversing (or other kinds of color symmetry) produce results that look less than natural. We produce images with approximate color symmetries by using the domain coloring algorithm with suitable complex Fourier series and photographs that have varying degrees of naturally occurring color symmetry. The technique yields patterns where the color symmetry looks less crystallographic than those previously produced, but perhaps more artistic. The technique produces an interesting combination of symmetrical and natural patterns.

Santa Clara Magazine, Volume 58 Number 2, Summer 2017, Santa Clara University

Santa Clara Magazine

18 - LISTENING IS HER SUPERPOWER The groundbreaking stage work of Anna Deavere Smith. By Jesse Hamlin.

22 - CASTS A SHADOW Travel bans: Four international graduate students respond. By Matt Morgan.

24 - A BIGGER STAGE Priest, social worker, CEO, and teller of stories: Jim Purcell on what drew him to Santa Clara—and what Jesuit education can be. By Steven Boyd Saum.

28 - THE GOOD, THE BAD, AND THE KID Ron Hansen M.A. ’95 talks truth and fiction and Billy the Kid—and when you can’t tell the good guys from the bad guys.

38 - DISCOVER. INNOVATE. A …

Climate Response To The 8.2 Ka Event In Coastal California, Jessica L. Oster, Warren D. Sharp, Aaron K. Covey, Jansen Gibson, Bruce Rogers, Hari T. Mix

Environmental Studies and Sciences

A fast-growing stalagmite from the central California coast provides a high-resolution record of climatic changes synchronous with global perturbations resulting from the catastrophic drainage of proglacial Lake Agassiz at ca. 8.2 ka. High frequency, large amplitude variations in carbon isotopes during the 8.2 ka event, coupled with pulsed increases in phosphorus concentrations, indicate more frequent or intense winter storms on the California coast. Decreased magnesium-calcium ratios point toward a sustained increase in effective moisture during the event, however the magnitude of change in Mg/Ca suggests this event was not as pronounced on the western North American coast as anomalies seen …

Projected Sensitivity Of The Supercdms Snolab Experiment, R. Agnese, A. J. Anderson, T. Aramaki, I. J. Arnquist, W. Baker, D. Barker, R. Basu Thakur, D. A. Bauer, A. Borgland, M. A. Bowles, P. L. Brink, R. Bunker, Blas Cabrera, D. O. Caldwell, R. Calkins, C. Cartaro, D. G. Cerdeño, H. Chagani, Y. Chen, J. Cooley, B. Cornell, P. Cushman, M. Daal, P.C. F. Di Stefano, T. Doughty, L. Esteban, S. Fallows, E. Figueroa-Feliciano, M. Fritts, G. Gerbier, M. Ghaith, G. L. Godfrey, S. R. Golwala, J. Hall, H. R. Harris, T. Hofer, D. Holmgren, Z. Hong, E. Hoppe, L. Hsu, M. E. Huber, V. Iyer, D. Jardin, A. Jastram, M. H. Kelsey, A. Kennedy, A. Kubik, N. A. Kurinsky, A. Leder, B. Loer, E. Lopez Asamar, P. Lukens, R. Mahapatra, V. Mandic, N. Mast, N. Mirabolfathi, R. A. Moffatt, J. D. Morales Mendoza, J. L. Orrell, S. M. Oser, K. Page, W. A. Page, R. Partridge, M. Pepin, A. Phipps, S. Poudel, M. Pyle, H. Qiu, W. Rau, P. Redl, A. Reisetter, A. Roberts, A. E. Robinson, H. E. Rogers, T. Saab, B. Sadoulet, J. Sander, K. Schneck, R. W. Schnee, B. Serfass, D. Speller, M. Stein, J. Street, H. A. Tanaka, D. Toback, R. Underwood, A. N. Villano, B. Von Krosigk, B. Welliver, J. S. Wilson, D. H. Wright, S. Yellin, J. J. Yen, Betty A. Young, X. Zhang, X. Zhao

Physics

SuperCDMS SNOLAB will be a next-generation experiment aimed at directly detecting low-mass (< 10 GeV/c²) particles that may constitute dark matter by using cryogenic detectors of two types (HV and iZIP) and two target materials (germanium and silicon). The experiment is being designed with an initial sensitivity to nuclear recoil cross sections ~ 1 x 10⁻⁴³ cm² for a dark matter particle mass of 1 GeV/c², and with capacity to continue exploration to both smaller masses and better sensitivities. The phonon sensitivity of the HV detectors will be sufficient to detect nuclear recoils from sub-GeV dark …

Room-Temperature Self-Powered Energy Photodetector Based On Optically Induced Seebeck Effect In Cd3As2, Niloufar Yavarishad, Tahereh Hosseini, Elaheh Kheirandish, Christopher P. Weber, Nikolai Kouklin

Physics

We demonstrate an intrinsically fast Seebeck-type metal–semimetal–metal infrared photodetector based on Cd₃As₂ crystals. The Seebeck voltage is induced under off-center illumination, leading to asymmetric temperature gradients and a net current flow. The room-temperature responsivity of the sensor is 0.27 mA/W. The photocurrent signal is readily registered at a modulation frequency of 6 kHz, and the intrinsic bandwidth of the sensor is predicted to approach the terahertz range. The photocurrent depends on the optical power and modulation frequency. Our study demonstrates that crystallineCd₃As₂ is a promising material for high-bandwidth and spectrally broad photosensing, imaging, and …

Santa Clara Magazine, Volume 58 Number 1, Spring 2017, Santa Clara University

Santa Clara Magazine

24 - BIG WIN FOR A TINY HOUSE Turning heads and changing the housing game. By Matt Morgan.

28 - $100 MILLION GIFT TO BUILD John A. ’60 and Susan Sobrato make the largest gift in SCU history. Now see the Sobrato Campus for Discovery and Innovation that will take shape—and redefine the University. Illustration by Tavis Coburn.

36 - CUT & PASTE CONSERVATION We can alter wild species to save them. So should we? By Emma Marris. Illustrations by Jason Holley.

44 - INFO OFFICER IN CHIEF From his office overlooking the White House, Tony Scott J.D. ’92 set …

Why Are Regulations Changed? A Parcel Analysis Of Upzoning In Los Angeles, C. J. Gabbe

Environmental Studies and Sciences

Planners, officials, and neighborhood groups often debate zoning changes, yet there is little empirical evidence explaining why zoning and other land use regulations are changed. I use logistic regression models to examine density-enabling rezoning (“upzoning”) in Los Angeles. I find that upzoning occurs where there are development opportunities combined with limited political resistance. Upzoning is most likely on well-located parcels zoned for low-intensity, nonresidential uses. Meanwhile, homeowners—and particularly homeowners with access to valuable amenities—are associated with regulatory stasis. I conclude by recommending strategies for addressing homeowners’ concerns about higher density housing.

Domain Coloring And The Argument Principle, Frank A. Farris

Mathematics and Computer Science

The domain-coloring algorithm allows us to visualize complex-valued functions on the plane in a single image—an alternative to before-and-after mapping diagrams. It helps us see when a function is analytic and aids in understanding contour integrals. The culmination of this article is a visual discovery and subsequent proof of the Argument Principle, which relates the count of poles and zeros of a meromorphic function inside a contour to the accumulated change in argument of the function around the contour. Throughout, I offer connections to standard learning goals of courses in complex variables.