Sun, Sep 21, 2008 page8

• [LETTERS]

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  Three misstatements

  We very much appreciated you publishing an article about our research (“New iron-based superconductor found,” Sept. 13, page 4). The article is quite well written in general. However, some corrections are needed in order to avoid confusion.

  First, the statement “Currently, the iron-based compound — dubbed ‘PbO type structure alpha-FeSe’ — can reach superconductive status at a temperature of 30 Kelvin” is not accurate. The FeSe superconductor has a transition temperature of 8K, and under pressure can reach 27K. Thus, it is important to stress that the higher transition temperature to the superconducting state can be achieved only under high pressure.

  Second, the statement “Superconductivity is a physical phenomenon in which certain materials, when cooled to very low temperatures such as zero Kelvin” could be misleading. Up to now, it has been very difficult to cool things to exactly zero Kelvin. The lowest attainable temperatures with liquid cryogenic methods are typically in the range of tens of milliKelvin, which is still somewhat larger than zero. Also, as seen with high-tc and iron superconductors, we observe transitions around 8K to 93K, which are larger than zero Kelvin.

  Finally, the statement “Meanwhile, a long-existing hypothesis about superconductors is that only substances that are anti-ferromagnetic in nature can be transformed into superconductors” is misphrased and somewhat incorrect. The hypothesis is that magnetism does not lead to superconductivity. Antiferromagnetism is in fact a form of magnetism that denotes how interacting spins align in an anti-parallel position. The high-tc superconductors are normally antiferromagnetic materials that become superconducting below their transition temperature. But the antiferromagnetism is not necessarily directly responsible for the superconductivity.

  Saying that only antiferromagnetic materials can become superconducting is a gross misstatement.

  MAW-KUEN WU

  Director

  Institute of Physics

  Academia Sinica

  Taipei

  Importance or impotence?

  Taiwanese sometimes have difficulty pronouncing the English words “importance” and “impotence.” The words might sound similar, but it seems that some can’t even tell them apart by their meanings.

  Minister of Transportation and Communications Mao Chi-kuo (毛治國) does not feel like saying sorry to the nation after “only” four bridges collapsed when Typhoon Sinlaku pelted Taiwan. The destruction does not seem to bother the minister: His important position has more important tasks than facing the families of victims and taking responsibility.

  Casualties and damage brought by the typhoon are increasing, the stock market is tumbling, tainted Chinese products are entering the market and the sovereignty of the country is being challenged.

  President Ma Ying-jeou’s (馬英九) important post also involves dealing with other more important issues, whatever they are. His schedule is hectic and includes dining with Chinese Nationalist Party (KMT) legislators.

  What else must happen on this island that would prompt the leaders of this country to reflect on the style of their leadership and make them aware that a sense of “importance” can be destructive? “Importance” leads to a failure to perform — to impotence.

  HANNA SHEN

  Taipei
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