Potassium clusters are incorporated into supercages of zeolite LTA crystals, with the supercages arrayed in a simple cubic structure at a number density of 5.3 x 10 20 cm " 3 . About four 4y electrons of K atoms are included in each cluster. The ac magnetic susceptibility increases dramatically with decreases in temperature below 8 K, and shows ferromagnetism below about 4 K. The effective magnetic moment per supercage is estimated to be about 0.13/x* at 1.7 K. Magnetic properties resemble those of a reentrant spin glass. PACS numbers: 75.50.Lk, 33.20.-t, 36.20.-r, 78.65.EzAn isolated metal cluster of a nonmagnetic element is expected to exhibit a magnetic moment when it has an odd number of electrons [1], The temperature dependence of the magnetic susceptibility of these clusters is expected to be of the Curie type [2]. If such clusters are arranged periodically and their magnetic moments mutually interact, the resulting materials are expected to be significantly different, with respect to magnetic properties, not only from the isolated clusters but also from the original bulk material. Very recently, ferromagnetism has been reported in organic molecular crystals with no magnetic element, such as p-NPNN [3] and C 6u TDAE [4]. In these materials, ferromagnetism may be realized by the mutual interaction between molecular magnetic moments or by itinerant electrons.The framework of zeolites is crystalline, and includes well defined cages specific to the type of zeolite. Cations, for example, Na + , are distributed in the space of the framework. The chemical formula is given as M n A\ n -Si m 02(/!+m), where M denotes the kind of cation. Alkali metal clusters of various sizes are generated in zeolites by introducing guest alkali metal atoms. Extensive optical and magnetic measurements have been performed on these materials [5-10].In LTA, which is a type of zeolite, supercages with an inner diameter of 11 A are arrayed in a simple cubic structure with a number density of 5.3x 10 20 cm -3 , and are connected by shared windows with an inner diameter of 5 A. In the present paper, K clusters are generated in the supercages of K-exchanged LTA, and the electronic interaction between K clusters is realized through the windows between the supercages. Such arrayed clusters are called a cluster crystal [11]. It is confirmed by the optical reflection spectrum that each K cluster includes about four As electrons of guest K atoms. It is revealed from the measurement of the ac magnetic susceptibility that the K cluster crystal shows ferromagnetism below about 4 K.Original Na-form LTA powder was transformed by ion exchange into K form in the KC1 aqueous solution, and washed with distilled water. The Si-to-Al ratio of LTA

An array of analytical techniques comprising powder X-ray diffraction, solid-state NMR spectroscopy, high-resolution transmission electron microscopy, nitrogen adsorption, and UV/vis diffuse reflectance spectroscopy has been applied to study the incorporation of indium phosphide semiconductor inside MCM-41 materials by metal organic chemical vapor deposition. Line broadening in the X-ray diffraction patterns suggests the existence of both large surface deposited indium phosphide particles and nanosized indium phosphide particles deposited within the pores. High-resolution transmission electron microscopy corroborates this result:  surface deposits have been imaged, and analysis of electron diffraction patterns provides evidence of the existence of nanoparticles. Nitrogen adsorption provides information on pore filling. Quantum-confinement effects, brought about by the nanoparticle size regime, are evidenced by upfield shifting of the indium phosphide resonance in the 31P magic-angle-spinning NMR spectra and by blue shifting of the band gap dependent transition in the UV/vis absorption spectra.

No abstract

In vortex-like spin arrangements, multiple spins can combine into emergent multipole moments. Such multipole moments have broken space-inversion and time-reversal symmetries, and can therefore exhibit linear magnetoelectric (ME) activity. Three types of such multipole moments are known: toroidal; monopole; and quadrupole moments. So far, however, the ME activity of these multipole moments has only been established experimentally for the toroidal moment. Here we propose a magnetic square cupola cluster, in which four corner-sharing square-coordinated metal-ligand fragments form a noncoplanar buckled structure, as a promising structural unit that carries an ME-active multipole moment. We substantiate this idea by observing clear magnetodielectric signals associated with an antiferroic ME-active magnetic quadrupole order in the real material Ba(TiO)Cu 4 (PO 4 ) 4 . The present result serves as a useful guide for exploring and designing new ME-active materials based on vortex-like spin arrangements.

No abstract