μSR study on ferromagnetism of potassium clusters in aluminosilicate zeolite LTA

Abstract

Potassium clusters stabilized in regular cages of aluminosilicate zeolite LTA are known to show ferromagnetic properties depending on the loading density of guest K atoms. In the present paper, a muon spin rotation/relaxation (μSR) experiment is reported for a sample at a K-loading density of 4.8 atoms per cage. This sample shows ferromagnetic properties below 6.5 K. An increase in the muon spin depolarization rate, a decrease in the initial asymmetry and an appearance of the muon spin precession signal are all observed at low temperatures in the zero field. The internal magnetic field distribution is roughly estimated from the depolarization rate and the precession frequency. Possible magnetic structures are discussed in comparison with the internal field distribution. A recovery of the initial asymmetry is observed for very weak longitudinal field (LF). This behavior is ascribed to the reorientation of spontaneous magnetization along LF. The present result is discussed in relation to the spin-canting model.