Antiferromagnetic resonance in alkali-metal clusters in sodalite
Abstract
We have performed electron spin resonance (ESR) studies of K43+ and (K3Rb)3+ nanoclusters incorporated in powder specimens of aluminosilicate sodalite at several microwave frequencies between 9 and 34 GHz. The K43+ and (K3Rb)3+ clusters are arrayed in a bcc structure and are known to show antiferromagnetic ordering below the Néel temperatures of TN ≃72 and ≃80 K, respectively, due to the exchange coupling between s electrons confined in the clusters. We have found sudden broadenings of ESR spectra in both samples below TN. The line shape of the spectra below TN is analyzed by powder pattern simulations of antiferromagnetic resonance (AFMR) spectra. The calculated line shapes well reproduce the experimental ones at all the frequencies by assuming a biaxial magnetic anisotropy. We have evaluated extremely small anisotropy fields of approximately 1 Oe indicating that these materials are ideal Heisenberg antiferromagnets. We have also found that the magnetic anisotropy changes from easy-plane type to uniaxial type by changing into a heavier alkali-metal cluster and that the g value shifts to a large value beyond two below TN for K43+ and (K3Rb)3+ nanoclusters. These novel features of K43+ and (K3Rb)3+ nanoclusters incorporated in sodalite are discussed.
- Publication:
-
Physical Review B
- Pub Date:
- November 2013
- DOI:
- 10.1103/PhysRevB.88.174401
- Bibcode:
- 2013PhRvB..88q4401N
- Keywords:
-
- 76.50.+g;
- 75.30.Gw;
- 71.20.Dg;
- 82.75.Vx;
- Ferromagnetic antiferromagnetic and ferrimagnetic resonances;
- spin-wave resonance;
- Magnetic anisotropy;
- Alkali and alkaline earth metals;
- Clusters in zeolites