The spin-1/2 coupled tetramer system Ba(TiO) Cu4(PO4)4 probed by magnetization, specific heat, and 31P NMR

[摘要] We present the synthesis and a detailed investigation of structural and magnetic properties of polycrystalline Ba(TiO) Cu-4(PO4)(4) (BTCPO) via X-ray diffraction, magnetic susceptibility, heat capacity, and P-31 Nuclear Magnetic Resonance (NMR) measurements. BTCPO has a 2D layered structure with interlinked Cu4O12 tetramer units. A broad maximum is observed around 16.5 K in our magnetization data accompanied by a sharp anomaly around T = 9.5 K in the heat capacity. An anomaly at about T = 10 K is also found in the temperature dependence of the P-31 NMR spin-lattice relaxation rate 1/T-1. A power law behavior for the heat capacity as well as for the P-31 1/ T-1 below the ordering temperature could be obtained. The P-31 NMR lineshape is asymmetric and the NMR shift tracks the bulk spin-susceptibility. We estimated the isotropic and axial components of the hyperfine coupling tensor to be as the A(hf)(iso) similar or equal to 6794Oe/mu(B) and A(hf)(ax) similar or equal to 818Oe/mu(B), respectively.

[发布日期] 2019-12-15