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Magnetic properties of carbon nanodisk and nanocone powders

机译：碳纳米盘和纳米锥粉的磁性

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摘要

We have investigated the magnetic properties of carbon powders which consist of nanodisks, nanocones, and a small fraction of carbon-black particles. Magnetization measurements were carried out using a superconducting quantum interference device in magnetic fields -5 < μ_0 H < 5 T for temperatures in the range 2 ≤ T < 350 K. Measurements of the magnetization M versus temperature T and magnetic field μ_0 H for these carbon samples show diamagnetism and paramagetism with an additional ferromagnetic contribution. The ferromagnetic magnetization is in agreement with the calculated magnetization from Fe impurities as determined by the particle-induced x-ray emission method (<75 μg/g). Magnetization measurements in weak magnetic fields show thermal hysteresis, and for strong fields the magnetization M decreases as M ～ aT~(-α) with α < 1, which is slower than the Curie law (α = 1), when the temperature increases. The magnetization M versus magnetic field μ_0 H shows paramagnetic free-spin S = 1/2 and 3/2 behaviors for temperatures T = 2K and 15 ≤ T ≤ 50 K, respectively. A tendency for localization of electrons was found by electron spin resonance when the temperature T decreases (2 < T < 40 K). The magnetic properties in these carbon cone and disk powder samples are more complex than a free-spin model predicts, which is apparently valid only for the temperature T=2K.
机译：我们已经研究了碳粉的磁性，该碳粉由纳米盘，纳米锥和一小部分炭黑颗粒组成。使用超导量子干涉装置在2≤T <350 K的温度范围内的磁场-5 <μ_0H <5 T下进行磁化测量。这些碳的磁化强度M与温度T的关系以及磁场μ_0H的测量样品显示出反磁性和顺磁性以及其他铁磁作用。铁磁磁化强度与根据粒子感应X射线发射法（<75μg/ g）确定的从Fe杂质计算出的磁化强度一致。弱磁场中的磁化强度测量显示出磁滞现象，强磁场中的磁化强度M随M〜aT〜（-α）的减小而减小，α<1，当温度升高时，磁化强度M小于居里定律（α= 1）。磁化强度M与磁场μ_0H的关系分别表明，温度T = 2K和15≤T≤50 K时，顺磁自由旋转S = 1/2和3/2。当温度T降低（2 ＜T ＜40K）时，通过电子自旋共振发现了电子的局部化趋势。这些碳锥和圆盘粉末样品中的磁性比自由旋转模型预测的要复杂，这显然仅对温度T = 2K有效。

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  • 来源
    《Physical review》 |2013年第1期|014434.1-014434.8|共8页
  • 作者

    Jozef Cernak; Geir Helgesen; Arne T. Skjeltorp; Jozef Kovac; Josef Voltr; Erik Cizmar;

  • 作者单位

    Institute of Physics, P. J. Safarik University in Kosice, Jesenna 5, SK-04000 Kosice, Slovak Republic;

    Institute for Energy Technology, Physics Department, NO-2007 Kjeller, Norway;

    Institute for Energy Technology, Physics Department, NO-2007 Kjeller, Norway;

    Laboratory of Nanomaterials and Applied Magnetism, Institute of Physics, Slovak Academy of Sciences, Watsonova 47, SK-04000 Kosice,Slovak Republic;

    Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, CZ-115 19 Praha 1, Czech Republic;

    Centre of Low Temperature Physics, P. J. Safarik University in Kosice, SK-04000 Kosice, Slovak Republic;

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  • 正文语种 eng
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  • 关键词

    nonmetals;

    机译：非金属;

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