The electronic structure and the phases of BaVS3

BaVS3 is a moderately correlated d-electron system with a rich phase diagram. To construct the corresponding minimal electronic model, one has to decide which d-states are occupied, and to which extent. The ARPES experiment presented here shows that the behavior of BaVS3 is governed by the coexistence of wide-band (A_1g) and narrow-band (twofold degenerate E) d-electrons. We sketch a lattice fermion model which may serve as a minimal model of BaVS3. This serves foremost for the understanding of the metal-insulator in pure BaVS3 and its absence in some related compounds. The nature of the low temperature magnetic order differs for several systems which may be described in terms of the same electron model. We describe several recent experiments which give information about magnetic order at high pressures. In particular, we discuss field-induced insulator-to-metal transition at slightly subcritical pressures, and an evidence for magnetic order in the high-pressure metallic phase. The phase diagram of Sr-doped BaVS3 is also discussed. The complexity of the phases of BaVS3 arises from the fact that it is simultaneously unstable against several kinds of instabilities.Comment: Presented at the International Conference on Magnetism 2006 (Kyoto), 6 pages, 9 figure

Optical conductivity of a metal-insulator transition for the Anderson-Hubbard model in 3 dimensions away from 1/2 filling

We have completed a numerical investigation of the Anderson-Hubbard model for three-dimensional simple cubic lattices using a real-space self-consistent Hartree-Fock decoupling approximation for the Hubbard interaction. In this formulation we treat the spatial disorder exactly, and therefore we account for effects arising from localization physics. We have examined the model for electronic densities well away 1/2 filling, thereby avoiding the physics of a Mott insulator. Several recent studies have made clear that the combined effects of electronic interactions and spatial disorder can give rise to a suppression of the electronic density of states, and a subsequent metal-insulator transition can occur. We augment such studies by calculating the ac conductivity for such systems. Our numerical results show that weak interactions enhance the density of states at the Fermi level and the low-frequency conductivity, there are no local magnetic moments, and the ac conductivity is Drude-like. However, with a large enough disorder strength and larger interactions the density of states at the Fermi level and the low-frequency conductivity are both suppressed, the conductivity becomes non-Drude-like, and these phenomena are accompanied by the presence of local magnetic moments. The low-frequency conductivity changes from a sigma-sigma_dc omega^{1/2} behaviour in the metallic phase, to a sigma omega^2 behaviour in the nonmetallic regime. Our numerical results show that the formation of magnetic moments is essential to the suppression of the density of states at the Fermi level, and therefore essential to the metal-insulator transition

Asymmetry between the electron- and hole-doped Mott transition in the periodic Anderson model

We study the doping driven Mott metal-insulator transition (MIT) in the periodic Anderson model set in the Mott-Hubbard regime. A striking asymmetry for electron or hole driven transitions is found. The electron doped MIT at larger U is similar to the one found in the single band Hubbard model, with a first order character due to coexistence of solutions. The hole doped MIT, in contrast, is second order and can be described as the delocalization of Zhang-Rice singlets.Comment: 18 pages, 19 figure

Isentropic Curves at Magnetic Phase Transitions

Experiments on cold atom systems in which a lattice potential is ramped up on a confined cloud have raised intriguing questions about how the temperature varies along isentropic curves, and how these curves intersect features in the phase diagram. In this paper, we study the isentropic curves of two models of magnetic phase transitions- the classical Blume-Capel Model (BCM) and the Fermi Hubbard Model (FHM). Both Mean Field Theory (MFT) and Monte Carlo (MC) methods are used. The isentropic curves of the BCM generally run parallel to the phase boundary in the Ising regime of low vacancy density, but intersect the phase boundary when the magnetic transition is mainly driven by a proliferation of vacancies. Adiabatic heating occurs in moving away from the phase boundary. The isentropes of the half-filled FHM have a relatively simple structure, running parallel to the temperature axis in the paramagnetic phase, and then curving upwards as the antiferromagnetic transition occurs. However, in the doped case, where two magnetic phase boundaries are crossed, the isentrope topology is considerably more complex

Geolocation Adaptive Music Player

date-added: 2017-12-22 20:02:39 +0000 date-modified: 2017-12-22 20:05:50 +0000 keywords: adaptive music, intelligent music player, semantic audio, feature extraction bdsk-url-1: https://smartech.gatech.edu/bitstream/handle/1853/54586/WAC2016-47.pdfdate-added: 2017-12-22 20:02:39 +0000 date-modified: 2017-12-22 20:05:50 +0000 keywords: adaptive music, intelligent music player, semantic audio, feature extraction bdsk-url-1: https://smartech.gatech.edu/bitstream/handle/1853/54586/WAC2016-47.pdfWe present a web-based cross-platform adaptive music player that combines music information retrieval (MIR) and audio processing technologies with the interaction capabilities offered by GPS-equipped mobile devices. The application plays back a list of music tracks, which are linked to geographic paths in a map. The music player has two main enhanced features that adjust to the location of the user, namely, adaptable length of the songs and automatic transitions between tracks. Music tracks are represented as data packages containing audio and metadata (descriptive and behavioral) that builds on the concept of Digital Music Object (DMO). This representation, in line with nextgeneration web technologies, allows for exible production and consumption of novel musical experiences. A content provider assembles a data pack with music, descriptive analysis and action parameters that users can experience and control within the restrictions and templates defined by the provider

Piano Pedaller: A Measurement System for Classification and Visualisation of Piano Pedalling Techniques

date-added: 2017-12-22 18:53:42 +0000 date-modified: 2017-12-22 19:03:05 +0000 keywords: piano gesture recognition, optical sensor, real-time data acquisition, bela, music informatics local-url: https://pdfs.semanticscholar.org/fd00/fcfba2f41a3f182d2000ca4c05fb2b01c475.pdf publisher-url: http://homes.create.aau.dk/dano/nime17/ bdsk-url-1: http://www.nime.org/proceedings/2017/nime2017_paper0062.pdfdate-added: 2017-12-22 18:53:42 +0000 date-modified: 2017-12-22 19:03:05 +0000 keywords: piano gesture recognition, optical sensor, real-time data acquisition, bela, music informatics local-url: https://pdfs.semanticscholar.org/fd00/fcfba2f41a3f182d2000ca4c05fb2b01c475.pdf publisher-url: http://homes.create.aau.dk/dano/nime17/ bdsk-url-1: http://www.nime.org/proceedings/2017/nime2017_paper0062.pdfdate-added: 2017-12-22 18:53:42 +0000 date-modified: 2017-12-22 19:03:05 +0000 keywords: piano gesture recognition, optical sensor, real-time data acquisition, bela, music informatics local-url: https://pdfs.semanticscholar.org/fd00/fcfba2f41a3f182d2000ca4c05fb2b01c475.pdf publisher-url: http://homes.create.aau.dk/dano/nime17/ bdsk-url-1: http://www.nime.org/proceedings/2017/nime2017_paper0062.pdfdate-added: 2017-12-22 18:53:42 +0000 date-modified: 2017-12-22 19:03:05 +0000 keywords: piano gesture recognition, optical sensor, real-time data acquisition, bela, music informatics local-url: https://pdfs.semanticscholar.org/fd00/fcfba2f41a3f182d2000ca4c05fb2b01c475.pdf publisher-url: http://homes.create.aau.dk/dano/nime17/ bdsk-url-1: http://www.nime.org/proceedings/2017/nime2017_paper0062.pdfdate-added: 2017-12-22 18:53:42 +0000 date-modified: 2017-12-22 19:03:05 +0000 keywords: piano gesture recognition, optical sensor, real-time data acquisition, bela, music informatics local-url: https://pdfs.semanticscholar.org/fd00/fcfba2f41a3f182d2000ca4c05fb2b01c475.pdf publisher-url: http://homes.create.aau.dk/dano/nime17/ bdsk-url-1: http://www.nime.org/proceedings/2017/nime2017_paper0062.pdfThis paper presents the results of a study of piano pedalling techniques on the sustain pedal using a newly designed measurement system named Piano Pedaller. The system is comprised of an optical sensor mounted in the piano pedal bearing block and an embedded platform for recording audio and sensor data. This enables recording the pedalling gesture of real players and the piano sound under normal playing conditions. Using the gesture data collected from the system, the task of classifying these data by pedalling technique was undertaken using a Support Vector Machine (SVM). Results can be visualised in an audio based score following application to show pedalling together with the player’s position in the score

Low-energy properties of two-dimensional quantum triangular antiferromagnets: Non-perturbative renormalization group approach

We explore low temperature properties of quantum triangular Heisenberg antiferromagnets in two dimension in the vicinity of the quantum phase transition at zero temperature. Using the effective field theory described by the $SO(3)\times SO(2)/SO(2)$ matrix Ginzburg-Landau-Wilson model and the non-perturbative renormalization group method, we clarify how quantum and thermal fluctuations affect long-wavelength behaviors in the parameter region where the systems exhibit a fluctuation-driven first order transition to a long-range ordered state. We show that at finite temperatures the crossover from a quantum $\phi^6$ theory to a renormalized two-dimensional classical nonlinear sigma model region appears, and in this crossover region, massless fluctuation modes with linear dispersion a la spin waves govern low-energy physics. Our results are in good agreement with the recent experimental observations for the two-dimensional triangular Heisenberg spin system, NiGa$_2$S$_4$.Comment: 14 pages,7 figures, version accepted for publication in Physical Review