Spin density functional study on magnetism of potassium loaded Zeolite A

In order to clarify the mechanism of spin polarization in potassium-loaded zeolite A, we perform {\em ab initio} density-functional calculations. We find that (i) the system comprising only non-magnetic elements (Al, Si, O and K) can indeed exhibit ferromagnetism, (ii) while the host cage makes a confining quantum-well potential in which $s$- and $p$-like states are formed, the potassium-4$s$ electrons accommodated in the p-states are responsible for the spin polarization, and (iii) the size of the magnetic moment sensitively depends on the atomic configuration of the potassium atoms. We show that the spin polarization can be described systematically in terms of the confining potential and the crystal field splitting of the p-states.