hide
Free keywords:
-
Abstract:
We present a combined experimental and theoretical study of the spin-1/2
compound CuP2O6 that features a network of two-dimensional (2D)
antiferromagnetic (AFM) square planes, interconnected via
one-dimensional (1D) AFM spin chains. Magnetic susceptibility,
high-field magnetization, and electron spin resonance (ESR) data, as
well as microscopic density-functional band-structure calculations and
subsequent quantum Monte Carlo simulations, show that the coupling J(2D)
similar or equal to 40 K in the layers is an order of magnitude larger
than J(1D) similar or equal to 3 K in the chains. Below T-N similar or
equal to 8 K, CuP2O6 develops long-range order, as evidenced by a weak
net moment on the 2D planes induced by anisotropic magnetic interactions
of Dzyaloshinsky-Moriya type. A striking feature of this 3D ordering
transition is that the 1D moments grow significantly slower than the
ones on the 2D units, which is evidenced by the persistent paramagnetic
ESR signal below T-N. Compared to typical quasi-2D magnets, the ordering
temperature of CuP2O6 T-N/J(2D) similar or equal to 0.2 is unusually
low, showing that weakly coupled spins sandwiched between 2D magnetic
units effectively decouple these units and impede the long-range
ordering.
