Observation of magnetically hard grain boundaries in double-perovskite Sr2FeMoO6
Observation of magnetically hard grain boundaries in double-perovskite Sr2FeMoO6
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DOI：
10.1209/0295-5075/108/27003
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发表时间：
2013-05
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通讯作者：
Y. Takahashi;V. K. Verma;G. Shibata;T. Harano;K. Ishigami;K. Yoshimatsu;T. Kadono;A. Fujimori;A. Tanaka;F. Chang;H.J. Lin;D. Huang;C. T. Chen;B. Pal;D. Sarma
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作者：
Y. Takahashi;V. K. Verma;G. Shibata;T. Harano;K. Ishigami;K. Yoshimatsu;T. Kadono;A. Fujimori;A. Tanaka;F. Chang;H.J. Lin;D. Huang;C. T. Chen;B. Pal;D. Sarma
铁磁 Sr2FeMoO6 多晶异常的低温磁阻 (MR) 归因于充当自旋阀的硬磁晶界。利用X射线吸收光谱（XAS）和X射线磁圆二色性（XMCD）不同探测模式的不同探测深度，即总电子产额（TEY）模式（探测深度 ）和总荧光产额（TFY）模式（探测深度 ），检测了多晶Sr2FeMoO6晶粒和晶界的不同磁滞曲线。在20 K时，TEY模式检测到的磁矫顽力比TFY模式大几倍，表明晶界的铁磁性比晶粒的铁磁性更强。在室温下，晶界磁性变软，并且 和 几乎相同。从XAS和XMCD谱的线形分析中，我们发现在晶界区域，铁磁性成分以Fe2+或屏蔽良好的信号为主，而非磁性成分以Fe3+或屏蔽不良的信号为主。
Unusual low-temperature magneto-resistance (MR) of ferromagnetic Sr2FeMoO6 polycrystals has been attributed to magnetically hard grain boundaries which act as spin valves. We detected the different magnetic hysteresis curves for the grains and the grain boundaries of polycrystalline Sr2FeMoO6 by utilizing the different probing depths of the different detection modes of x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD), namely, the total electron yield (TEY) mode (probing depth ) and the total fluorescence yield (TFY) mode (probing depth ). At 20 K, the magnetic coercivity detected in the TEY mode was several times larger than that in the TFY mode , indicating harder ferromagnetism of the grain boundaries than that of the grains. At room temperature, the grain boundary magnetism became soft and and were nearly the same. From the line-shape analysis of the XAS and XMCD spectra, we found that in the grain boundary region the ferromagnetic component is dominated by Fe2+ or well-screened signals, while the non-magnetic component is dominated by Fe3+ or poorly screened signals.