C. -M. Kuo - Stanford University

C. -M. Kuo
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C. -M. Kuo
Stanford University
United States

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Cosmology and Nongalactic Astrophysics (14)
Computer Science - Computer Vision and Pattern Recognition (12)
Instrumentation and Methods for Astrophysics (10)
Physics - Strongly Correlated Electrons (7)
Physics - Materials Science (4)
Astrophysics of Galaxies (3)
Nuclear Experiment (2)
Physics - Medical Physics (2)
High Energy Physics - Theory (2)
Physics - Superconductivity (2)
High Energy Physics - Phenomenology (2)
Computer Science - Multimedia (2)
General Relativity and Quantum Cosmology (2)
Physics - Mesoscopic Systems and Quantum Hall Effect (1)
Mathematics - Optimization and Control (1)
Quantitative Biology - Quantitative Methods (1)
Physics - Optics (1)
Physics - Biological Physics (1)
Computer Science - Learning (1)
Computer Science - Artificial Intelligence (1)
Quantitative Biology - Genomics (1)
Statistics - Methodology (1)
Quantum Physics (1)
High Energy Astrophysical Phenomena (1)

Publications Authored By C. -M. Kuo

The design, analysis and application of a volumetric convolutional neural network (VCNN) are studied in this work. Although many CNNs have been proposed in the literature, their design is empirical. In the design of the VCNN, we propose a feed-forward K-means clustering algorithm to determine the filter number and size at each convolutional layer systematically. Read More

A novel solution for the content-based 3D shape retrieval problem using an unsupervised clustering approach, which does not need any label information of 3D shapes, is presented in this work. The proposed shape retrieval system consists of two modules in cascade: the irrelevance filtering (IF) module and the similarity ranking (SR) module. The IF module attempts to cluster gallery shapes that are similar to each other by examining global and local features simultaneously. Read More

There is a resurging interest in developing a neural-network-based solution to the supervised machine learning problem. The convolutional neural network (CNN) will be studied in this note. To begin with, we introduce a RECOS transform as a basic building block of CNNs. Read More

A new methodology to measure coded image/video quality using the just-noticeable-difference (JND) idea was proposed. Several small JND-based image/video quality datasets were released by the Media Communications Lab at the University of Southern California. In this work, we present an effort to build a large-scale JND-based coded video quality dataset. Read More

The ferromagnetic semiconductor Ba2NiOsO6 (Tmag ~100 K) was synthesized at 6 GPa and 1500 {\deg}C. It crystallizes into a double perovskite structure [Fm-3m; a = 8.0428(1) {\AA}], where the Ni2+ and Os6+ ions are perfectly ordered at the perovskite B-site. Read More

We demonstrate a series of InGaN/GaN double quantum well nanostructure elements. We grow a layer of 2 {\mu}m undoped GaN template on top of a (0001)-direction sapphire substrate. A 100 nm SiO2 thin film is deposited on top as a masking pattern layer. Read More

We have investigated the electronic structure of Sr2IrO4 using core level resonant inelastic x-ray scattering. The experimental spectra can be well reproduced using ab initio density functional theory based multiplet ligand field theory calculations, thereby validating these calculations. We found that the low-energy, effective Ir t2g orbitals are practically degenerate in energy. Read More

As part of the Megamaser Cosmology Project (MCP), we present VLBI maps of nuclear water masers toward five galaxies. The masers originate in sub-parsec circumnuclear disks. For three of the galaxies, we fit Keplerian rotation curves to estimate their supermassive black hole (SMBH) masses, and determine (2. Read More

Polarization leakage of foreground synchrotron emission is a critical issue in HI intensity mapping experiments. While the sought-after HI emission is unpolarized, polarized foregrounds such as Galactic and extragalactic synchrotron radiation, if coupled with instrumental impurity, can mimic or overwhelm the HI signals. In this paper we present the methodology for polarization calibration at 700-900 MHz, applied on data obtained from the Green Bank Telescope (GBT). Read More


This book lays out the scientific goals to be addressed by the next-generation ground-based cosmic microwave background experiment, CMB-S4, envisioned to consist of dedicated telescopes at the South Pole, the high Chilean Atacama plateau and possibly a northern hemisphere site, all equipped with new superconducting cameras. CMB-S4 will dramatically advance cosmological studies by crossing critical thresholds in the search for the B-mode polarization signature of primordial gravitational waves, in the determination of the number and masses of the neutrinos, in the search for evidence of new light relics, in constraining the nature of dark energy, and in testing general relativity on large scales. Read More

We perform optical spectroscopy measurement across the charge density wave (CDW) phase transitions on single-crystal samples of Sr$_{3}$Rh$_{4}$Sn$_{13}$ and (Sr$_{0.5}$Ca$_{0.5}$)$_{3}$Rh$_{4}$Sn$_{13}$. Read More

This work attempts to address two fundamental questions about the structure of the convolutional neural networks (CNN): 1) why a non-linear activation function is essential at the filter output of every convolutional layer? 2) what is the advantage of the two-layer cascade system over the one-layer system? A mathematical model called the "REctified-COrrelations on a Sphere" (RECOS) is proposed to answer these two questions. After the CNN training process, the converged filter weights define a set of anchor vectors in the RECOS model. Anchor vectors represent the frequently occurring patterns (or the spectral components). Read More

Role discovery in graphs is an emerging area that allows analysis of complex graphs in an intuitive way. In contrast to other graph prob- lems such as community discovery, which finds groups of highly connected nodes, the role discovery problem finds groups of nodes that share similar graph topological structure. However, existing work so far has two severe limitations that prevent its use in some domains. Read More

Increasing accessibility of data to researchers makes it possible to conduct massive amounts of statistical testing. Rather than follow a carefully crafted set of scientific hypotheses with statistical analysis, researchers can now test many possible relations and let P-values or other statistical summaries generate hypotheses for them. Genetic epidemiology field is an illustrative case in this paradigm shift. Read More

Inherent loss is always to be avoided in generating single photons or biphotons, but interestingly it provides opportunities for manipulating the photon wave packet. In this paper we show how inherent loss in parametric down-conversion can be employed to tailor the wave packets of single photons and biphotons. As an example, we propose a scheme to realize a single photon in a single cycle using inherent loss. Read More

The superconductor-to-insulator transition (SIT) induced by means such as external magnetic fields, disorder or spatial confinement is a vivid illustration of a quantum phase transition dramatically affecting the superconducting order parameter. In pursuit of a new realization of the SIT by interfacial charge transfer, we developed extremely thin superlattices composed of high $T_c$ superconductor YBa$_2$Cu$_3$O$_7$ (YBCO) and colossal magnetoresistance ferromagnet La$_{0.67}$Ca$_{0. Read More

BICEP3 is a small-aperture refracting cosmic microwave background (CMB) telescope designed to make sensitive polarization maps in pursuit of a potential B-mode signal from inflationary gravitational waves. It is the latest in the BICEP/Keck Array series of CMB experiments at the South Pole, which has provided the most stringent constraints on inflation to date. For the 2016 observing season, BICEP3 was outfitted with a full suite of 2400 optically coupled detectors operating at 95 GHz. Read More

The task of estimating the spatial layout of cluttered indoor scenes from a single RGB image is addressed in this work. Existing solutions to this problems largely rely on hand-craft features and vanishing lines, and they often fail in highly cluttered indoor rooms. The proposed coarse-to-fine indoor layout estimation (CFILE) method consists of two stages: 1) coarse layout estimation; and 2) fine layout localization. Read More

We present measurements of polarization lensing using the 150 GHz maps which include all data taken by the BICEP2 & Keck Array CMB polarization experiments up to and including the 2014 observing season (BK14). Despite their modest angular resolution ($\sim 0.5^\circ$), the excellent sensitivity ($\sim 3\mu$K-arcmin) of these maps makes it possible to directly reconstruct the lensing potential using only information at larger angular scales ($\ell\leq 700$). Read More

We observe quasi-static incommensurate magnetic peaks in neutron scattering experiments on layered cobalt oxides La2-xSrxCoO4 with high Co oxidation states that have been reported to be paramagnetic. This enables us to measure the magnetic excitations in this highly hole-doped incommensurate regime and compare our results with those found in the low-doped incommensurate regime that exhibit hourglass magnetic spectra. The hourglass shape of magnetic excitations completely disappears given a high Sr doping. Read More

An approach that extracts global attributes from outdoor images to facilitate geometric layout labeling is investigated in this work. The proposed Global-attributes Assisted Labeling (GAL) system exploits both local features and global attributes. First, by following a classical method, we use local features to provide initial labels for all super-pixels. Read More

A novel algorithm for uncalibrated stereo image-pair rectification under the constraint of geometric distortion, called USR-CGD, is presented in this work. Although it is straightforward to define a rectifying transformation (or homography) given the epipolar geometry, many existing algorithms have unwanted geometric distortions as a side effect. To obtain rectified images with reduced geometric distortions while maintaining a small rectification error, we parameterize the homography by considering the influence of various kinds of geometric distortions. Read More

The problem of stereoscopic image quality assessment, which finds applications in 3D visual content delivery such as 3DTV, is investigated in this work. Specifically, we propose a new ParaBoost (parallel-boosting) stereoscopic image quality assessment (PBSIQA) system. The system consists of two stages. Read More

Semantic segmentation is critical to image content understanding and object localization. Recent development in fully-convolutional neural network (FCN) has enabled accurate pixel-level labeling. One issue in previous works is that the FCN based method does not exploit the object boundary information to delineate segmentation details since the object boundary label is ignored in the network training. Read More

A robust two-stage shape retrieval (TSR) method is proposed to address the 2D shape retrieval problem. Most state-of-the-art shape retrieval methods are based on local features matching and ranking. Their retrieval performance is not robust since they may retrieve globally dissimilar shapes in high ranks. Read More

Textual data such as tags, sentence descriptions are combined with visual cues to reduce the semantic gap for image retrieval applications in today's Multimodal Image Retrieval (MIR) systems. However, all tags are treated as equally important in these systems, which may result in misalignment between visual and textual modalities during MIR training. This will further lead to degenerated retrieval performance at query time. Read More

Megamaser disks provide the most precise and accurate extragalactic supermassive black hole masses. Here we describe a search for megamasers in nearby galaxies using the Green Bank Telescope (GBT). We focus on galaxies where we believe that we can resolve the gravitational sphere of influence of the black hole and derive a stellar or gas dynamical measurement with optical or NIR observations. Read More

BICEP3 is a $550~mm$ aperture telescope with cold, on-axis, refractive optics designed to observe at the $95~GHz$ band from the South Pole. It is the newest member of the BICEP/Keck family of inflationary probes specifically designed to measure the polarization of the cosmic microwave background (CMB) at degree-angular scales. BICEP3 is designed to house 1280 dual-polarization pixels, which, when fully-populated, totals to $\sim$9$\times$ the number of pixels in a single Keck $95~GHz$ receiver, thus further advancing the BICEP/Keck program's $95~GHz$ mapping speed. Read More

Fast Radio Bursts are bright, unresolved, non-repeating, broadband, millisecond flashes, found primarily at high Galactic latitudes, with dispersion measures much larger than expected for a Galactic source. The inferred all-sky burst rate is comparable to the core-collapse supernova rate out to redshift 0.5. Read More

As part of the Megamaser Cosmology Project (MCP), here we present a new geometric distance measurement to the megamaser galaxy NGC 5765b. Through a series of VLBI observations, we have confirmed the water masers trace a thin, sub-parsec Keplerian disk around the nucleus, implying an enclosed mass of 4.55 $\pm$ 0. Read More

Spectator fragments resulting from relativistic heavy ion collisions, consisting of single protons and neutrons along with groups of stable nuclear fragments up to Nitrogen (Z=7), are measured in PHOBOS. These fragments are observed in Au+Au (sqrt(sNN)=19.6 GeV) and Cu+Cu (22. Read More

Based on the notion of just noticeable differences (JND), a stair quality function (SQF) was recently proposed to model human perception on JPEG images. Furthermore, a k-means clustering algorithm was adopted to aggregate JND data collected from multiple subjects to generate a single SQF. In this work, we propose a new method to derive the SQF using the Gaussian Mixture Model (GMM). Read More

From magnetic susceptibility, dielectric permittivity, electric polarization and specific heat measurements, we discover spin-induced ferroelectricity and magnetoelectric coupling in Mn3TeO6 and observe two successive magnetic transitions at low temperatures. A non-ferroelectric intermediate magnetic state occurs below 23 K and a multiferroic ground state emerges below 21 K. Moreover, Mn3TeO6 is a candidate for a multiferroic material where two types of incommensurate spin structures, cycloidal and helical, coexist. Read More

Affiliations: 1Cardiff University, 2Cardiff University, 3Cardiff University, 4Cardiff University, 5KIPAC/SLAC, 6Caltech, 7Harvard/CfA, 8Harvard/CfA, 9Harvard/CfA, 10Harvard/CfA, 11Harvard/CfA, 12Harvard/CfA, 13Harvard/CfA, 14Harvard/CfA, 15Minnesota Institute for Astrophysics, 16Harvard/CfA, 17Harvard/CfA, 18NASA JPL, 19SBT Grenoble, 20Harvard, 21Caltech, 22University of Minnesota, 23Stanford University, 24University of British Columbia, 25Harvard/CfA, 26NIST, 27Caltech, 28Stanford University, 29Harvard/CfA, 30Stanford University, 31UCSD, 32UCSD, 33Caltech, 34Stanford University, 35Harvard/CfA, 36Stanford University, 37KICP/Chicago, 38Caltech, 39NASA JPL, 40University of Toronto, 41NASA JPL, 42Caltech, 43Stanford University, 44Caltech, 45University of Minnesota, 46Harvard/CfA, 47University of Minnesota, 48University of Minnesota, 49Caltech, 50Caltech, 51Cardiff University, 52Caltech, 53Stanford University, 54Stanford University, 55Cardiff University, 56NASA JPL, 57Harvard/CfA, 58NASA JPL, 59University of British Columbia, 60University of Minnesota, 61Harvard/CfA, 62Stanford University, 63Stanford University

We present results from an analysis of all data taken by the BICEP2 & Keck Array CMB polarization experiments up to and including the 2014 observing season. This includes the first Keck Array observations at 95 GHz. The maps reach a depth of 50 nK deg in Stokes $Q$ and $U$ in the 150 GHz band and 127 nK deg in the 95 GHz band. Read More

Forward calorimetry in the PHOBOS detector has been used to study charged hadron production in d+Au, p+Au and n+Au collisions at sqrt(s_nn) = 200 GeV. The forward proton calorimeter detectors are described and a procedure for determining collision centrality with these detectors is detailed. The deposition of energy by deuteron spectator nucleons in the forward calorimeters is used to identify p+Au and n+Au collisions in the data. Read More

We study thin films and magnetic tunnel junction nanopillars based on Ta/Co$_{20}$Fe$_{60}$B$_{20}$/MgO multilayers by electrical transport and magnetometry measurements. These measurements suggest that an ultrathin magnetic oxide layer forms at the Co$_{20}$Fe$_{60}$B$_{20}$/MgO interface. At approximately 160 K, the oxide undergoes a phase transition from an insulating antiferromagnet at low temperatures to a conductive weak ferromagnet at high temperatures. Read More

Demixing is the problem of identifying multiple structured signals from a superimposed observation. This work analyzes a general framework, based on convex optimization, for solving demixing problems. We present a new solution to determine whether or not a specific convex optimization problem built for generalized demixing is successful. Read More

Inertial sensors are commonly used to measure human head motion. Some sensors have been validated with dummy or cadaver experiments, but methods to evaluate sensors in vivo are lacking. Here we present an in vivo method using high speed video to evaluate teeth-mounted (mouthguard), soft tissue-mounted (skin patch), and headgear-mounted (skull cap) sensors during 6-13g sagittal soccer head impacts. Read More

Compared to imaging in the visible and near-infrared regions below 900 nm, imaging in the second near-infrared window (NIR-II, 1000-1700 nm) is a promising method for deep-tissue high-resolution optical imaging in vivo mainly due to the reduced scattering of photons traversing through biological tissues. Herein, semiconducting single-walled carbon nanotubes with large diameters were used for in vivo fluorescence imaging in the long-wavelength NIR region (1500-1700 nm, NIR-IIb). With this imaging agent, 3-4 um wide capillary blood vessels at a depth of about 3 mm could be resolved. Read More

BICEP2 and the Keck Array are polarization-sensitive microwave telescopes that observe the cosmic microwave background (CMB) from the South Pole at degree angular scales in search of a signature of inflation imprinted as B-mode polarization in the CMB. BICEP2 was deployed in late 2009, observed for three years until the end of 2012 at 150 GHz with 512 antenna-coupled transition edge sensor bolometers, and has reported a detection of B-mode polarization on degree angular scales. The Keck Array was first deployed in late 2010 and will observe through 2016 with five receivers at several frequencies (95, 150, and 220 GHz). Read More

Authors: BICEP2/Keck, Planck Collaborations, :, P. A. R. Ade, N. Aghanim, Z. Ahmed, R. W. Aikin, K. D. Alexander, M. Arnaud, J. Aumont, C. Baccigalupi, A. J. Banday, D. Barkats, R. B. Barreiro, J. G. Bartlett, N. Bartolo, E. Battaner, K. Benabed, A. Benoît, A. Benoit-Lévy, S. J. Benton, J. -P. Bernard, M. Bersanelli, P. Bielewicz, C. A. Bischoff, J. J. Bock, A. Bonaldi, L. Bonavera, J. R. Bond, J. Borrill, F. R. Bouchet, F. Boulanger, J. A. Brevik, M. Bucher, I. Buder, E. Bullock, C. Burigana, R. C. Butler, V. Buza, E. Calabrese, J. -F. Cardoso, A. Catalano, A. Challinor, R. -R. Chary, H. C. Chiang, P. R. Christensen, L. P. L. Colombo, C. Combet, J. Connors, F. Couchot, A. Coulais, B. P. Crill, A. Curto, F. Cuttaia, L. Danese, R. D. Davies, R. J. Davis, P. de Bernardis, A. de Rosa, G. de Zotti, J. Delabrouille, J. -M. Delouis, F. -X. Désert, C. Dickinson, J. M. Diego, H. Dole, S. Donzelli, O. Doré, M. Douspis, C. D. Dowell, L. Duband, A. Ducout, J. Dunkley, X. Dupac, C. Dvorkin, G. Efstathiou, F. Elsner, T. A. Enßlin, H. K. Eriksen, E. Falgarone, J. P. Filippini, F. Finelli, S. Fliescher, O. Forni, M. Frailis, A. A. Fraisse, E. Franceschi, A. Frejsel, S. Galeotta, S. Galli, K. Ganga, T. Ghosh, M. Giard, E. Gjerløw, S. R. Golwala, J. González-Nuevo, K. M. Górski, S. Gratton, A. Gregorio, A. Gruppuso, J. E. Gudmundsson, M. Halpern, F. K. Hansen, D. Hanson, D. L. Harrison, M. Hasselfield, G. Helou, S. Henrot-Versillé, D. Herranz, S. R. Hildebrandt, G. C. Hilton, E. Hivon, M. Hobson, W. A. Holmes, W. Hovest, V. V. Hristov, K. M. Huffenberger, H. Hui, G. Hurier, K. D. Irwin, A. H. Jaffe, T. R. Jaffe, J. Jewell, W. C. Jones, M. Juvela, A. Karakci, K. S. Karkare, J. P. Kaufman, B. G. Keating, S. Kefeli, E. Keihänen, S. A. Kernasovskiy, R. Keskitalo, T. S. Kisner, R. Kneissl, J. Knoche, L. Knox, J. M. Kovac, N. Krachmalnicoff, M. Kunz, C. L. Kuo, H. Kurki-Suonio, G. Lagache, A. Lähteenmäki, J. -M. Lamarre, A. Lasenby, M. Lattanzi, C. R. Lawrence, E. M. Leitch, R. Leonardi, F. Levrier, A. Lewis, M. Liguori, P. B. Lilje, M. Linden-Vørnle, M. López-Caniego, P. M. Lubin, M. Lueker, J. F. Macías-Pérez, B. Maffei, D. Maino, N. Mandolesi, A. Mangilli, M. Maris, P. G. Martin, E. Martínez-González, S. Masi, P. Mason, S. Matarrese, K. G. Megerian, P. R. Meinhold, A. Melchiorri, L. Mendes, A. Mennella, M. Migliaccio, S. Mitra, M. -A. Miville-Deschênes, A. Moneti, L. Montier, G. Morgante, D. Mortlock, A. Moss, D. Munshi, J. A. Murphy, P. Naselsky, F. Nati, P. Natoli, C. B. Netterfield, H. T. Nguyen, H. U. Nørgaard-Nielsen, F. Noviello, D. Novikov, I. Novikov, R. O'Brient, R. W. Ogburn IV, A. Orlando, L. Pagano, F. Pajot, R. Paladini, D. Paoletti, B. Partridge, F. Pasian, G. Patanchon, T. J. Pearson, O. Perdereau, L. Perotto, V. Pettorino, F. Piacentini, M. Piat, D. Pietrobon, S. Plaszczynski, E. Pointecouteau, G. Polenta, N. Ponthieu, G. W. Pratt, S. Prunet, C. Pryke, J. -L. Puget, J. P. Rachen, W. T. Reach, R. Rebolo, M. Reinecke, M. Remazeilles, C. Renault, A. Renzi, S. Richter, I. Ristorcelli, G. Rocha, M. Rossetti, G. Roudier, M. Rowan-Robinson, J. A. Rubiño-Martín, B. Rusholme, M. Sandri, D. Santos, M. Savelainen, G. Savini, R. Schwarz, D. Scott, M. D. Seiffert, C. D. Sheehy, L. D. Spencer, Z. K. Staniszewski, V. Stolyarov, R. Sudiwala, R. Sunyaev, D. Sutton, A. -S. Suur-Uski, J. -F. Sygnet, J. A. Tauber, G. P. Teply, L. Terenzi, K. L. Thompson, L. Toffolatti, J. E. Tolan, M. Tomasi, M. Tristram, M. Tucci, A. D. Turner, L. Valenziano, J. Valiviita, B. Van Tent, L. Vibert, P. Vielva, A. G. Vieregg, F. Villa, L. A. Wade, B. D. Wandelt, R. Watson, A. C. Weber, I. K. Wehus, M. White, S. D. M. White, J. Willmert, C. L. Wong, K. W. Yoon, D. Yvon, A. Zacchei, A. Zonca

We report the results of a joint analysis of data from BICEP2/Keck Array and Planck. BICEP2 and Keck Array have observed the same approximately 400 deg$^2$ patch of sky centered on RA 0h, Dec. $-57. Read More

We have developed antenna-coupled transition-edge sensor (TES) bolometers for a wide range of cosmic microwave background (CMB) polarimetry experiments, including BICEP2, Keck Array, and the balloon borne SPIDER. These detectors have reached maturity and this paper reports on their design principles, overall performance, and key challenges associated with design and production. Our detector arrays repeatedly produce spectral bands with 20%-30% bandwidth at 95, 150, or 220~GHz. Read More

Affiliations: 1Cardiff University, 2Cardiff University, 3Cardiff University, 4Cardiff University, 5Stanford University, 6Caltech, 7Harvard/CfA, 8ALMA, 9University of Toronto, 10Harvard/CfA, 11Caltech, 12Caltech, 13Harvard/CfA, 14Minnesota Institute for Astrophysics, 15Harvard/CfA, 16Harvard/CfA, 17Caltech, 18NASA JPL, 19Harvard/CfA, 20SBT Grenoble, 21Caltech, 22University of Minnesota, 23Caltech, 24University of British Columbia, 25University of British Columbia, 26Caltech, 27NIST, 28Caltech, 29Caltech, 30Stanford University, 31Harvard/CfA, 32UCSD, 33UCSD, 34Caltech, 35Stanford University, 36Harvard/CfA, 37Stanford University, 38KICP, 39Caltech, 40Caltech, 41NASA JPL, 42University of Toronto, 43NASA JPL, 44NASA JPL, 45Stanford University, 46UCSD, 47University of Minnesota, 48NIST, 49Harvard/CfA, 50University of Minnesota, 51KICP, 52Caltech, 53Cardiff University, 54Caltech, 55Stanford University, 56Stanford University, 57NASA JPL, 58KICP, 59NASA JPL, 60University of Minnesota, 61Harvard/CfA, 62Stanford University

The Keck Array is a system of cosmic microwave background (CMB) polarimeters, each similar to the BICEP2 experiment. In this paper we report results from the 2012 and 2013 observing seasons, during which the Keck Array consisted of five receivers all operating in the same (150 GHz) frequency band and observing field as BICEP2. We again find an excess of B-mode power over the lensed-$\Lambda$CDM expectation of $> 5 \sigma$ in the range $30 < \ell < 150$ and confirm that this is not due to systematics using jackknife tests and simulations based on detailed calibration measurements. Read More

We report a study of the local magnetism in thin films of SrRuO3 grown on (111) and (001) oriented SrTiO3 substrates using x-ray magnetic circular dichroism spectroscopy (XMCD) at the Ru-L2,3 edges. The application of the sum rules to the XMCD data gives an almost quenched orbital moment and a spin moment close to the value expected for the low spin state S = 1 . Full-multiplet cluster calculations indicate that the low spin state is quite stable and suggest that the occurrence of a transition to the high spin state S = 2 in strained thin films of SrRuO3 is unlikely as it would be too expensive in energy. Read More

The half-metallic Heusler compound Co$_2$MnSi is a very attractive material for spintronic devices because it exhibits very high tunnelling magnetoresistance ratios. This work reports on a spectroscopic investigation of thin Co$_2$MnSi films as they are used as electrodes in magnetic tunnel junctions. The investigated films exhibit a remanent in-plane magnetisation with a magnetic moment of about 5~$\mu_B$ when saturated, as expected. Read More

21cm intensity mapping experiments aim to observe the diffuse neutral hydrogen (HI) distribution on large scales which traces the Cosmic structure. The Square Kilometre Array (SKA) will have the capacity to measure the 21cm signal over a large fraction of the sky. However, the redshifted 21cm signal in the respective frequencies is faint compared to the Galactic foregrounds produced by synchrotron and free-free electron emission. Read More