2026-10-11T00:26:22Z https://api.figshare.com/v2/oai

oai:figshare.com:article/33742482 2026-09-14T14:09:02Z category_4 category_915 category_7 category_15 category_16 category_128 portal_63 item_type_3 month_year_09_2026

Competing Magnetic Superexchange Interactions in Layered Vanadyl Phosphate Hydrates Lovro Šarić (24887388) Ivica Živković (3345752) Rebecca Scatena (1472455) Matthias Krack (1370997) Simon Grabowsky (1347333) Lorraine A. Malaspina (5121119) Sergey V. Churakov (1796839) Georgia Cametti (6724670) Biochemistry Physical Sciences not elsewhere classified Medicine Neuroscience Physiology Hematology ≈ 4 k magnetization measurements reveal interlayer coupling plays ferromagnetic response along electronic structure description density functional theory antiferromagnetic response within range spin correlations bridging phosphate group orbital populations obtained vo )< sub >< sub >< heat capacity measurements dimensional magnetic ordering 2 </ sub heat capacity dimensional ordering dimensional correlations phosphate groups orbital polarization molecular orbital dimensional order n </ c </ ab </ 3 </ ></ sub type interactions type anomaly trimeric units straightforward determination results highlight reduced λ neighbour exchange multipole model moment orientation metal centers magnetocrystalline anisotropy leading role ground state gradual crossover comprehensive investigation compounds exhibit complex behaviour >- plane >- axis We present a comprehensive investigation of the layered vanadyl phosphate hydrates Ni(VO)₂(PO₄)₂·4H₂O (NiVP) and Co(VO)₂(PO₄)₂·4H₂O (CoVP), combining anisotropic magnetic susceptibility, heat capacity measurements, Density Functional Theory (DFT) calculations, and X-ray charge density analysis. Magnetization measurements reveal a ferromagnetic response along the crystallographic <i>c</i>-axis and an antiferromagnetic response within the <i>ab</i>-plane. Both compounds exhibit the presence of magnetocrystalline anisotropy, consistent with an easy-plane anisotropic magnetic state in NiVP, while in CoVP, strong spin–orbit coupling leads to a more complex behaviour that prevents a straightforward determination of the moment orientation. Prior to the onset of three-dimensional magnetic ordering at <i>T</i>_<i>N</i> ≈ 4 K, both systems develop significant short-range spin correlations, as evidenced by deviations from the Curie–Weiss behaviour and a reduced λ-type anomaly in heat capacity, indicating a gradual crossover from low-dimensional correlations to three-dimensional ordering. DFT calculations consistently identify a ground state of columnar antiferromagnetic intralayer ordering and ferromagnetic interlayer coupling mediated by trimeric units. The exchange hierarchy indicates anisotropic intralayer interactions dominated by next-nearest-neighbour exchange, while interlayer coupling plays a leading role in establishing a three-dimensional order. Comparison between <i>3</i>d orbital populations obtained from multipole model-refined experimental charge densities and DFT Mulliken analysis shows good agreement, validating the electronic structure description. The results highlight the importance of orbital polarization in establishing different superexchange pathways through phosphate groups, with interlayer coupling primarily governed by σ-type interactions and intralayer exchange involving π-mediated interactions, mediated by the molecular orbital of the bridging phosphate group between the metal centers. 2026-09-14T00:00:00Z Dataset Dataset 10.1021/acs.jpcc.6c04951.s001 https://figshare.com/articles/dataset/Competing_Magnetic_Superexchange_Interactions_in_Layered_Vanadyl_Phosphate_Hydrates/33742482 CC BY-NC 4.0