37,582 research outputs found
Strong Reduction of the Field-Dependent Microwave Surface Resistance in YBCO with BaZrO_3 Inclusions
We present measurements of the magnetic field dependent microwave surface
resistance in laser-ablated YBaCuO films on SrTiO
substrates. BaZrO crystallites were included in the films using composite
targets containing BaZrO inclusions with mean grain size smaller than 1
m. X-ray diffraction showed single epitaxial relationship between
BaZrO and YBaCuO. The effective surface resistance was
measured at 47.7 GHz for 6090 K and 00.8 T. The magnetic
field had a very different effect on pristine YBaCuO and
YBaCuO/BaZrO, while for 0 only a reduction of
in the YBaCuO/BaZrO film was observed,
consistent with dc measurements. At low enough , in moderate fields
YBaCuO/BaZrO exhibited an intrinsic thin film
resistance lower than the pure film. The results clearly indicate that
BaZrO inclusions determine a strong reduction of the field-dependent
surface resistance. From the analysis of the data in the framework of simple
models for the microwave surface impedance in the mixed state we argue that
BaZrO inclusions determine very steep pinning potentials.Comment: LaTeX, 6 pages, 4 figures, uses jpconf.cls and jpconf11.clo class
files, talk given at EUCAS 2007, submitted to J. Phys.: Conf. Serie
Efeito do herbicida chlorimuron-ethyl no crescimento da mamoneira em solos com diferentes características químicas e físicas.
Efeito do tamanho e peso sobre a germinação de sementes de pupunha (Bactris gasipaes KUNTH.).
Resumo 39
Propagação vegetativa de velame, uma espécie medicinal nativa da Caatinga.
Objetivou-se com este trabalho, avaliar o efeito da auxina ácido naftalenoacético no enraizamento de estacas de velame.Suplemento. Edição dos Anais do 52 Congresso Brasileiro de Olericultura, Salvador, jul. 2012
Temperature dependence of antiferromagnetic susceptibility in ferritin
We show that antiferromagnetic susceptibility in ferritin increases with
temperature between 4.2 K and 180 K (i. e. below the N\'{e}el temperature) when
taken as the derivative of the magnetization at high fields (
Oe). This behavior contrasts with the decrease in temperature previously found,
where the susceptibility was determined at lower fields ( Oe). At
high fields (up to Oe) the temperature dependence of the
antiferromagnetic susceptibility in ferritin nanoparticles approaches the
normal behavior of bulk antiferromagnets and nanoparticles considering
superantiferromagnetism, this latter leading to a better agreement at high
field and low temperature. The contrast with the previous results is due to the
insufficient field range used ( Oe), not enough to saturate the
ferritin uncompensated moment.Comment: 7 pages, 7 figures, accepted in Phys. Rev.
Influência do tempo de exposição em ácido indol butírico no enraizamento de estacas de velame.
Suplemento. Edição dos Anais do 52 Congresso Brasileiro de Olericultura, Salvador, jul. 2012
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