A5019774759- Rare-earth and actinide compounds
- Iron-based superconductors research
- Magnetic and transport properties of perovskites and related materials
- Magnetic Properties of Alloys
- Superconductivity in MgB2 and Alloys
- Advanced Condensed Matter Physics
- Physics of Superconductivity and Magnetism
- Chemistry Education and Research
- Experimental and Theoretical Physics Studies
- Inorganic Chemistry and Materials
- Theoretical and Computational Physics
- Quantum Chromodynamics and Particle Interactions
- Boron and Carbon Nanomaterials Research
- Lanthanide and Transition Metal Complexes
- Education Pedagogy and Practices
- Inorganic Fluorides and Related Compounds
- History of Education Research in Brazil
- Nuclear physics research studies
- Advanced Thermoelectric Materials and Devices
- Chalcogenide Semiconductor Thin Films
- Magnetism in coordination complexes
- Education and Digital Technologies
- Iron oxide chemistry and applications
- Science and Education Research
- Quantum Dots Synthesis And Properties
Universidade Federal Rural do Semi-Árido
2014-2023
Universidade Estadual de Campinas (UNICAMP)
2009-2015
Electron spin resonance (ESR) can probe conduction electrons (CE) and local moment (LM) systems in different materials. A CE (CESR) is observed metallic based on light elements or with enhanced Pauli susceptibility. LM ESR be seen compounds paramagnetic ions localized d f electrons. Here we report a remarkable unprecedented signal the heavy-fermion superconductor β-YbAlB₄ [S. Nakatsuji et al., Nature Phys. 4, 603 (2008)] which behaves as CESR at high temperatures acquires characteristics of...
Electron spin resonance (ESR) experiments at different fields or frequencies $(4.1\ensuremath{\le}\ensuremath{\nu}\ensuremath{\le}34.4\text{ }\text{GHz})$ in the Kondo lattice $({T}_{K}\ensuremath{\simeq}25\text{ }\text{K})$ ${\text{YbRh}}_{2}{\text{Si}}_{2}$ single-crystal compounds confirmed observation of a single anisotropic Dysonian with ${g}_{\ensuremath{\perp}c}\ensuremath{\cong}3.55$ and no hyperfine components for $4.2\ensuremath{\lesssim}T\ensuremath{\lesssim}20\text{ }\text{K}$....
Single crystals of the type-I clathrate series Sr${}_{8\ensuremath{-}x}$Eu${}_{x}$Ga${}_{16}$Ge${}_{30}$ ($x=0.01$--8) were grown by Ga flux and systematically studied magnetic susceptibility, electrical resistivity, electron spin resonance (ESR) measurements. Both transition temperatures (${T}_{c}$ ${T}^{*}$) mapped as a function $x$. We found that Curie temperature (${T}_{c}$) anomaly (${T}^{*}$) decrease Eu is substituted Sr until no ordering observed above 2 K for $x=1.0$. For samples...
We report temperature dependent X-band (ν~9.5GHz) electron spin resonance (ESR) experiments in type-I clathrate Eu8Ga16Ge30. This system presents interesting thermoelectric properties its paramagnetic state and orders ferromagnetically below TC=35K. Although the Eu2+ ions sits on two inequivalent sites structure, we found a single Dysonian ESR line with nearly independent g~2 is observed, linewidth follows Korringa-like behavior as function of temperature. The microscopic details exchange...
This work reports on electron spin resonance experiments in oriented single crystals of the hexagonal AlB 2 diboride compound (P6/mmm, D16h structure) which display conduction resonance.The X-band spectra showed a metallic Dysonian with g-value and intensity independent temperature.The thermal broadening anisotropic linewidth H tracks T-dependence electrical resistivity below T 100 K.These results confirm observation are discussed comparison other boride compounds.Based our main findings for...
The Electron Spin Resonance (ESR) of diluted magnetic ions (MI) Er3+, Yb3+ and Mn2+ in Ag nanoparticles (NPs) is reported. Monodisperse samples NPs doped with these MI were synthesized by reducing silver nitrate MI-oxides. This simple method can be extended to all rare-earths. measurements the g-values hyperfine splittings indicates that are located at cubic sites Ag:MI NPs. ESR spectra show there no g-shift Korringa-relaxation due exchange interaction between conduction electrons,...
We report evidence for a close relation between the thermal activation of rattling motion filler guest atoms and inhomogeneous spin dynamics Eu${}^{2+}$ spins. The is probed directly by means electron resonance (ESR), performed in both $X$-band ($\ensuremath{\approx}$$9.4$ GHz) $Q$-band ($\ensuremath{\approx}$34 frequencies temperature interval $4.2\phantom{\rule{0.28em}{0ex}}\text{K}\ensuremath{\lesssim}T\ensuremath{\lesssim}300$ K. A comparative study with ESR measurements on...
β-YbAlB4 has become one of the most studied heavy fermion systems since its discovery due to remarkable physical properties. This system is first reported Yb-based heavy-fermion superconductor (HFS) for which low-T superconducting state emerges from a non-fermi-liquid (NFL) normal associated with quantum criticality Nakatsuji et al 2008 Nature 4 603. Additionally, it presents striking and unprecedented electron spin resonance (ESR) signal behaves as conduction (CESR) at high temperatures...
This paper presents the synthesis and characterization of colloidal NaYF4 NaYF4:20% Gd lanthanide nanocrystals. The nanoparticles were prepared by chemical route using co-thermolysis Na(CF3COO), Y(CF3COO)3 Gd(CF3COO)3 precursor in oleylamine surfactant/phenylether at Ts = 250 degrees C. By tuning precursor/surfactant molar ratio during process, it was possible to control crystalline phase, order size nanocrystals characterized Transmission Electron Microscopy, Small Angle X-ray Scattering,...
Neste trabalho abordaremos dois problemas teóricos, não muito discutidos na maioria das universidades brasileiras, envolvendo a Teoria da Relatividade Especial (TRE) e do Eletromagnetismo (TEM). Tais exemplos são de fundamental importância para uma completa compreensão natureza dos campos elétrico magnético induzidos, bem como o desenvolvimento conceitos TRE. Eles podem ser em sala aula juntamente com contextualização histórica acerca evolução eletricidade magnetismo que culminaram...
Electron Spin Resonance (ESR) can microscopically probe both conduction electrons (ce) and local moment (LM) spin systems in different materials. A ce resonance (CESR) is observed metallic based on light elements or with enhanced Pauli susceptibility. LM ESR frequently seen compounds paramagnetic ions localized d f electrons. Here we report a remarkable unprecedented signal the heavy fermion (HF) superconductor beta-YbAlB4[1] which behaves as CESR at high temperatures acquires...
Resumo Neste trabalho apresentamos um estudo da eletrostática aplicada aos sistemas coloidais cujo intuito é fornecer alunos de graduação e pós-graduação em Física material didático complementar que possibilite uma visão mais ampla dos conceitos estudados sala através aplicação direta teoria. Para tanto, utilizamos modelo sistema coloidal a partir do qual derivamos as expressões para Força, Campo Potencial elétricos, tanto distribuições discretas carga como contínuas. Encontramos ainda...
In this work we have performed Electron Spin Resonance (ESR) experiments on single crystals of Fe-doped YbAlB4 heavy fermion compounds. We explored the ESR measurements in X-band (η = 9,4 GHz). For β-YbAlB4, for and found a remarkable signal that behaves as conduction electron spin resonance (CESR) at high temperatures acquires characteristics Yb(3+) local moment low temperature. This behavior was not α-YbAlB4. The striking unique dual observed same spectra β-YbAlB4 associated to results...
Nanostructured materials are characterized by the existence of particles/ phases in length scales between 1 and 100 nm range where size reduction effects may originate either unusual or different properties from corresponding bulk [1]. In addition to their potential applications, fundamental physical aspects these systems represent a fascinating issue be tackled. this paper we report details about synthesis, structural magnetic ions (RE = Er3+ , Yb3+ Mn2+ ) diluted Ag colloidal nanoparticles...
Neste trabalho desenvolvemos as equações referentes ao movimento de uma esfera lisa na presença forças arrasto, no regime altas velocidades, onde a força resistiva é proporcional quadrado sua velocidade. Esse comumente encontrado em várias situações do cotidiano que objetos toda natureza são arremessadas ar. As estudadas nos cursos básicos graduação desconsideram o arrasto ar e, portanto, idealizadas, não condizentes com real observado. Aqui, pretendemos auxiliar leitor viajar um pouco mais...
The in∞uence of flnite sample size efiects and structural defects on the ground state Er 3+ in diluted Ag:Er alloys is studied. choused metallic systems were, nanoparticles (5{ 10nm) alloy Ag1ixErx (x = 0:04) bulk 0:001) which was used as a reference. were prepared by chemical synthesis that gives an excellent morphological crystalline homogeneity conventional arc-melting. resonant microwave absorption (Electron Spin Resonance) at X (9.5GHz)-band obtained low-T (4{20K) show T-independent...
Resumo Um problema importante no estudo de materiais magnéticos é saber como esses sistemas se comportam na presença um campo magnético externo. A resposta para esse está susceptibilidade magnética. Neste trabalho realizamos uma abordagem estatística das propriedades magnéticas dos levando em consideração suas interações microscópicas. Nosso intuito apresentar maneira didática e acessível estudante graduação as origens do fenômeno fases termodinâmicas, paramagnética, ferromagnética...