Enhanced magnetic properties and spin–phonon coupling in Ni-substituted α-Cu2V2O7: the role of bond length, bond angles, and distorted polyhedral structures

Abstract

Undoped and Ni-doped Cu_2−xNi_xV₂O₇ samples were synthesized and their structure [using X ray diffraction (XRD)], local structure [using X ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS)], magnetic properties (via temperature- and field-dependent magnetization measurement) and vibrational modes (via temperature-dependent Raman measurement) were analysed. XRD, XANES, EXAFS and Raman studies confirm that Ni was incorporated substitutionally at the Cu position. However, Ni incorporation increases the asymmetry of those bonds and bond angles that control magnetic exchanges in Cu₂V₂O₇. Temperature-dependent magnetization measurements indicate a slight monotonic downshift of the transition temperature (T_N) with increasing Ni doping, while field-dependent study shows an increase in magnetic hysteresis upon Ni doping and zero field cool exchange bias. Temperature-dependent Raman spectra show strong spin–phonon coupling (SPC) upon Ni incorporation. Overall, Ni-doped Cu₂V₂O₇ is promising for spintronics applications owing to its superior magnetic properties and thermo-magnetic potential.