Magnet levitation at your fingertips

被引:120
作者
Geim, AK [1 ]
Simon, MD
Boamfa, MI
Heflinger, LO
机构
[1] Catholic Univ Nijmegen, High Field Magnet Lab, NL-6525 ED Nijmegen, Netherlands
[2] Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA
关键词
D O I
10.1038/22444
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
The stable levitation of magnets is forbidden by Earnshaw's theorem, which states that no stationary object made of magnets in a fixed configuration can be held in stable equilibrium by any combination of static magnetic or gravitational forces1,2,3. Earnshaw's theorem can be viewed as a consequence of the Maxwell equations, which do not allow the magnitude of a magnetic field in a free space to possess a maximum, as required for stable equilibrium. Diamagnets (which respond to magnetic fields with mild repulsion) are known to flout the theorem, as their negative susceptibility results in the requirement of a minimum rather than a maximum in the field's magnitude2,3,4. Nevertheless, levitation of a magnet without using superconductors is widely thought to be impossible. We find that the stable levitation of a magnet can be achieved using the feeble diamagnetism of materials that are normally perceived as being non-magnetic, so that even human fingers can keep a magnet hovering in mid-air without touching it.
引用
收藏
页码:323 / 324
页数:2
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