<div dir="ltr"><div class="gmail_quote"><div dir="ltr"><div class="gmail_quote"><div><p class="MsoNormal" align="center" style="font-family:verdana,geneva,sans-serif;text-align:center"><u><span lang="ES" style="font-family:arial,sans-serif">SEMINARIOS  DEL
IFLP y DEL DEPARTAMENTO</span></u></p>

<p class="MsoNormal" align="center" style="font-family:verdana,geneva,sans-serif;text-align:center"><u><span style="font-family:arial,sans-serif">MARTES 14 de FEBRERO – 11 hs<span></span></span></u></p>

<p class="MsoNormal" align="center" style="font-family:verdana,geneva,sans-serif;text-align:center"><u><span lang="EN-US" style="font-family:arial,sans-serif">AULA CHICA<span></span></span></u></p><p class="MsoNormal" align="center" style="font-family:verdana,geneva,sans-serif;text-align:center"><u><span lang="EN-US" style="font-family:arial,sans-serif"><br></span></u></p>

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<p class="MsoNormal" style="font-family:verdana,geneva,sans-serif"><u><span style="font-family:arial,sans-serif">TÍTULO</span></u><span lang="PT-BR" style="font-family:arial,sans-serif">: </span><span style="font-family:arial,sans-serif">"RELATIVISTIC ELECTRON GAS: A NATURAL
METAMATERIAL"</span><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span></span></span></p>

<p class="MsoNormal" style="font-family:verdana,geneva,sans-serif;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span style="font-family:arial,sans-serif;color:rgb(69,69,69)"><span> </span></span></p><p class="MsoNormal" style="font-family:verdana,geneva,sans-serif;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><u><span style="font-family:arial,sans-serif">EXPOSITOR:</span></u><span style="font-family:arial,sans-serif"> </span><span class="m_-8447916132023530584gmail-Ninguno"><span lang="PT-BR" style="font-family:arial,sans-serif">C. A. A. de Carvalho</span></span></p><p class="MsoNormal" style="font-family:verdana,geneva,sans-serif;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><i><span lang="ES-TRAD"><font size="2">Instituto de Física,
Universidade Federal do Rio de Janeiro - UFRJ, Rio de Janeiro-RJ, Brazil</font></span></i></p><p class="MsoNormal" style="font-family:verdana,geneva,sans-serif;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><i><span lang="ES-TRAD">Centro Brasileiro
de Pesquisas Físicas – CBPF, Rio de Janeiro-RJ, Brazil</span></i></p><p class="MsoNormal" style="font-family:verdana,geneva,sans-serif;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span class="m_-8447916132023530584gmail-Ninguno">e-</span><span class="m_-8447916132023530584gmail-Ninguno"><span lang="PT-BR">mail</span></span><span class="m_-8447916132023530584gmail-Ninguno">: </span><span lang="EN-US"><a href="mailto:aragao@if.ufrj.br" target="_blank"><span lang="ES-AR">aragao@if.ufrj.br</span></a></span><span class="m_-8447916132023530584gmail-Ninguno">; </span><span lang="EN-US"><span lang="ES-AR"><a href="mailto:aragao@cbpf.br" target="_blank">aragao@cbpf.br</a></span></span></p>

<p class="MsoNormal" style="font-family:verdana,geneva,sans-serif;text-align:justify"><u><span lang="EN-US" style="font-family:arial,sans-serif"><br></span></u></p><p class="MsoNormal" style="font-family:verdana,geneva,sans-serif;text-align:justify"><u><span lang="EN-US" style="font-family:arial,sans-serif">Resumen:</span></u><span lang="EN-US" style="font-family:arial,sans-serif">
</span><span lang="PT-BR" style="color:rgb(35,31,32)">The electric permittivities and magnetic permeabilities for a
relativistic electron gas are calculated fromquantum electrodynamics at finite
temperature and density as functions of temperature, chemical potential,
frequency, and wave vector. The polarization and the magnetization depend
linearly on both electric and magnetic fields, and are the sum of a
zero-temperature and zero-density vacuum part with a temperature and
chemical-potential-dependent medium part [1]. In the nonrelativistic limit,
results reproduce the Lindhard formula. In the relativistic case, results
unambiguously indicate that the relativistic electron gas is one of nature’s
candidates for the realization of a negative index of refraction system.
Maxwell’s equations in the medium yield the dispersion relation and the index
ofrefraction of the electron gas. </span><span lang="PT-BR">Moreover, a discussion is presented of </span><span lang="PT-BR">applications to condensed-matter systems leading</span><span lang="PT-BR"> to good agreement with
experimental measurements of the plasmon energy in graphite and tin oxide, as
functions of both the temperature and wave vector [2]. We also derive
expressions for the real and imaginary parts of the EM responses, and relate
them to decays [3] into pairs (electron-hole or electron-positron).</span><span lang="PT-BR" style="color:rgb(35,31,32)">Present
results should be relevant for plasma physics, astrophysical observations,
synchrotrons, and other environments with fast-moving electrons.</span><span lang="PT-BR">Furthermore, </span><span lang="PT-BR">the present
electromagnetic response of a relativistic Fermi gas at finitetemperatures
could be of potential interest in future plasmonic and photonic investigations.<span></span></span></p>

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