Frustration of square cupola in Sr(TiO) Cu4(PO4)4

Abstract

The structural and magnetic properties of the square-cupola antiferromagnet Sr(TiO)Cu4(PO4)4 are investigated via x-ray diffraction, magnetization, heat capacity, and 31 P nuclear magnetic resonance experiments on polycrystalline samples, as well as density-functional band-structure calculations. The temperature-dependent unit cell volume could be described well using the Debye approximation with the Debye temperature of θD 550 K. Magnetic response reveals a pronounced two-dimensionality with a magnetic long-range-order below TN 6.2 K. High-field magnetization exhibits a kink at 1/3 of the saturation magnetization. Asymmetric 31 P NMR spectra clearly suggest strong in-plane anisotropy in the magnetic susceptibility, as anticipated from the crystal structure. From the 31 P NMR shift vs bulk susceptibility plot, the isotropic and axial parts of the hyperfine coupling between 31 P nuclei and the Cu 2+ spins are calculated to be A iso hf 6539 and A ax hf 952 Oe/µB, respectively. The low-temperature and low-field 31 P NMR spectra indicate a commensurate antiferromagnetic ordering. Frustrated nature of the compound is inferred from the temperature-dependent 31 P NMR spin-lattice relaxation rate and confirmed by our microscopic analysis that reveals strong frustration of the square cupola by next-nearest-neighbor exchange couplings.

Quasi-one-dimensional uniform spin- 12 Heisenberg antiferromagnet KNaCuP2O7 probed by Guchhait1, Ding2, Sahoo3 et al. 2021Phys. Rev. BSelf Cite

“…The core diamagnetic susceptibility (χ core ) of the compound was calculated to be −1.15 × 10 −4 cm 3 /mol by adding the core diamagnetic susceptibility of Na + , K + , Cu 2+ , P 5+ , and O 2− ions [45]. The Van Vleck paramagnetic susceptibility (χ vv ) was estimated to be ∼3.16 × 10 −4 cm 3 /mol by subtracting χ core from χ 0 , which is very close to the value reported for other Cu 2+ -based compounds [13,17,46].…”

Quantum magnetism of ferromagnetic spin dimers in $α$-KVOPO$_4$

“…Figure 7 presents the 31 P NMR spectra measured at different temperatures. We observed a single spectral line at high temperatures but the line shape is found to be asymmetric, similar to that observed for Zn 2 VO(PO 4 ) 2 and Sr(TiO)Cu 4 (PO 4 ) 4 [45,46]. The single spectral line implies that both the P-sites are almost equivalent.…”

Synthesis and Investigation of Magnetic Properties of Rod Shaped Micron Sized Ni4 and Co2Ni2 Cluster based MOFs

“…Thus, the AFM intra-cluster exchange interactions are expected to cause strong magnetic frustration in the compound. [25] Further, our χ(T) analysis points towards the coexisting AFM and FM interactions in both the compounds. [26] This implies that there is significant inter-cluster coupling which is FM in nature.…”