A ideia deste artigo é discutir a afirmação que surgiu durante o trabalho de campo desenvolvido entre músicos populares indígenas do Noroeste Amazônico brasileiro: todo instrumento musical possui “alma”. A partir dessa afirmação, busca-se desenvolver relatos etnográficos para sustentar que na prática da música popular entre os Yepá-mahsã, os instrumentos musicais são percebidos como  “pessoas” (não-humanas). Desse modo, a música kuximawara do Noroeste Amazônico constitui uma cena fértil para o pensamento e prática indígena, especialmente no que se refere à música ritual do cotidiano. Para a reflexão, expõe-se um pequeno conjunto de dados etnográficos no qual exemplos descritivos apresentados pelos interlocutores demonstram como a música popular articula conceitos e práticas do pensamento indígena do povo Yepá-mahsã. Esses exemplos buscam evidenciar como os instrumentos musicais “estrangeiros” são concebidos por meio da cosmologia indígena e se relacionam com a origem dos “instrumentos sagrados”. Reflito, inversamente, como a ideia de um instrumento “moderno” como a guitarra foi, pouco a pouco, descontruindo-se para que eu compreendesse que, a partir da lógica Yepá-mahsã, todos os instrumentos musicais do mundo eram resultantes da ação dos deuses em um passado mitológico.

This dissertation presents experimental research on the electronic structures of threecrystalline materials using a combination of spectroscopic techniques. In the topological material Hf2Te2P, topological surface states are revealed using scanning tunneling microscopy and angle-resolved photoemission spectroscopy. The surface states exist in distinct regions of energy-momentum space and show the potential for the conductive properties of the material to be controlled via tuning of the Fermi level. In the cuprate superconductor La1.475Nd0.4Sr0.125CuO4, the effects of uniaxial stress on the strong electronic correlations are measured using resonant x-ray scattering. Uniaxial stress is shown to be a powerful tool for tuning the electronic phases of the material by causing large decreases in the onset temperatures of both the charge stripes and structural deformations. In the iron-based superconductor FeSe0.77S0.23, charge ordering is identified using scanning tunneling spectroscopy. The presence of charge order originating from orbital-selective electronic correlations provides new insight into development of superconductivity in the FeSe1−xSx family. Altogether, these studies uncover new electronic properties of the materials with the goal of finding practical uses of their unique properties.

This work will present experimental results on two projects measuring the electronic properties of unconventional superconductors. The first project focuses on the iron-based superconductor system of FeSe1-xSx. We used scanning tunneling microscopy/spectroscopy (STM/S) to make detailed measurements of the electronic states of tetragonal FeSe0.89S 0.19. We also performed theoretical band structure calculations that were calibrated by angle-resolved photoemission spectroscopy measurements for comparison. We utilize the high spatial resolution of the STM/S measurements to separately analyze modulations in the local density of states (LDOS) in regions near and away from iron-vacancies. This analysis revealed two types of features: (i) energy dispersive quasiparticle interference patterns which can explained by our band structure calculations and (ii) a much stronger modulation just above the Fermi level centered at q=0.12 Å-1 which does not disperse with energy and cannot be explained by our band structure model. Local rotational symmetry analysis shows that while the modulations are four-fold symmetric on average, they are actually comprised of small domains with two-fold symmetry. Statistical analysis demonstrates that the boundaries of these domains are spatially correlated with the locations of iron-vacancies.

The second project studies charge order in the La-based cuprate La1.475Nd0.4Sr0.125CuO4. We performed temperature and uniaxial strain dependent resonant x-ray scattering studies on the charge order and the low-temperature orthorhombic to low-temperature tetragonal (LTO-LTT) structural transition. Before applying any strain, we found a precursor charge order peak existing up to 200 K, well above the static charge order onset temperature. Upon applying uniaxial tensile strain of about 0.1%, we observed a reduction in the onset of charge order by 50 K and a 20 K reduction in the LTO-LTT transition temperature. We also saw a preference for the charge order to form in the direction of applied strain due to a 6 K difference in onset temperatures for the two directions.