Intrinsic magnetic order in Cs2 AgF4 detected by muon-spin relaxation
Lancaster T., Blundell SJ., Baker PJ., Hayes W., Giblin SR., McLain SE., Pratt FL., Salman Z., Jacobs EA., Turner JFC., Barnes T.
We present the results of a muon-spin relaxation study of the high- Tc analog material Cs2 AgF4. We find unambiguous evidence for magnetic order, intrinsic to the material, below TC =13.95(3) K. The ratio of interplane to intraplane coupling is estimated to be J′ J =1.9× 10-2, while fits of the temperature dependence of the order parameter reveal a critical exponent β=0.292(3), implying an intermediate character between pure two- and three-dimensional magnetism in the critical regime. Above TC we observe a signal characteristic of dipolar interactions due to linear F- μ+ -F bonds, allowing the muon stopping sites in this compound to be characterized. © 2007 The American Physical Society.