Measurement of the gradient of the Casimir force between a nonmagnetic gold sphere and a magnetic nickel plate

We measured the gradient of the Casimir force between an Au sphere and a plate made of ferromagnetic metal (Ni). It is demonstrated that the magnetic properties influence the force magnitude. This opens prospective opportunities for the control of the Casimir force in nanotechnology and for obtaining Casimir repulsion by using ferromagnetic dielectrics.

Figure 1

(a) The values of the residual potential $V_0$ found at each separation distance are shown as dots. The mean value of $V_0$ is shown by the white line. (b) The systematic error of each individual $V_0$, as determined from the fit, versus separation.

Figure 2

The dependences of (a) the closest sphere-plate separation and (b) the coefficient $C$ in Eq. (2) on the end point of the fit.

Figure 3

The random, systematic, and total experimental errors in the gradient of the Casimir force determined at a 67$\%$ confidence level are shown by the short-dashed, long-dashed, and solid lines, respectively, as functions of separation.

Figure 4

Comparison between the experimental data for the gradient of the Casimir force (crosses) and theory (solid and dashed bands computed using the plasma model approach with included and omitted magnetic properties of the Ni plate, respectively).