Magnetic properties of the low-dimensional cuprateNa5RbCu4(AsO<

Synthesis and structure of a new family of 3d–4f heterometallic compounds Rb7LnFe6O2(PO4)8 (Ln=Sm, Eu, Gd, Dy): Magnetic properties of the Sm-, Gd-, Dy-derivatives

“…In 3d-4f heterometallic solids, it has reportedly been realized that, while the f-f interactions are weak due to buried electrons, the interaction of the f electrons with the more expanded s, p, or d electrons should be relatively stronger [1]. We have therefore expanded our search for new magnetic insulators that contain nanostructures of 3d transition metal oxide [10][11][12][13][14][15][16][17][18][19][20][21][22][23] into that of 3d-4f heterometallics in hopes to explore unusual magnetic phenomena associated with electronically confined systems and in part to gain insight into 3d-4f magnetic interactions. Our efforts in exploratory synthesis for new 3d-4f extended solids have led to interesting findings in the most recently reported Na 3 LnMn 3 O 3 (AsO 4 ) 3 (Ln¼La, Sm, Gd) [6] and Na 2 LnMnO(AsO 4 ) 2 (Ln¼Sm, Gd, Dy) [8] series.…”

Structural phase transition in two-dimensional tetramer-cuprate Na5RbCu4(AsO4)4Cl2

“…The insulating layer consists of an ionic framework of mixed alkali metal chloride lattices and rarely seen Na 6 O 8 clusters. Also the room temperature crystal structure of Na 5 RbCu 4 (AsO 4 ) 4 Cl 2 was reported as orthorhombic (space group Fmmm, Z = 2) [4]. The low-temperature crystal structure, which may have crucial implications for the distinct magnetic order, has not been determined until now.…”

“…This compound exhibits a composite structure of alternating magnetic and insulating layers. The magnetic layer contains [Cu 4 O 12 ] 16-tetrameric units with Cu 4 O 4 magnetic cores, which are connected by AsO 4 bridging units. The copper valence state is 2+, so the Cu ions are magnetic with spin 1 2 .…”

“…Following this line two-dimensional systems with pronounced magnetic fluctuations, competing interactions and structural instabilities have been discovered and investigated [1,2]. Recently a new salt-inclusion copper arsenate Na 5 RbCu 4 (AsO 4 ) 4 Cl 2 with a remarkable crystal structure was synthesized using a conventional solid-state reaction [3]. This compound exhibits a composite structure of alternating magnetic and insulating layers.…”

Quantum phase transition in the Plaquette lattice with anisotropic spin exchange

“…Based on the findings of a recent experimental study of a new compound N a 5 RbCu 4 (AsO 4 ) 4 Cl 2 [1] I will examine a quantum spin system which shows a purely quantum phase transition by singlet formation. This and related models have been studied previously [2,3,4].…”