Brief Communication Arising

Nature 455, E13 (30 October 2008) | doi:10.1038/nature07437; Received 27 May 2008; Accepted 28 August 2008

The fourth circuit element

Neil D. Mathur1

Arising from: D. B. Strukov, G. S. Snider, D. R. Stewart & R. S. Williams Nature 453, 80–83 (2008)

In 1971, Chua suggested1 that there should in principle exist a circuit element linking electrical charge, q, and magnetic flux, phi. Strukov et al. 2 claim recently to have found such a link. However, here I point out that Chua's suggestion was in fact preceded by experimental evidence3, 4, 5 for magneto-electric effects whereby magnetic and electrical signals are interconverted. When the stimulus is magnetic and the response is electrical, the linear magneto-electric coupling constant5, alpha, is typically reported as dP/dH, where P represents the electrical polarization and H represents the applied magnetic field. The coupling constant could equally be presented as dq/dphi if divided by the permeability of free space.

  1. Department of Materials Science, New Museums Site, Pembroke Street, Cambridge CB2 3QZ, UK.


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