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dc.contributor.authorSubhash Thotaen
dc.contributor.authorMohindar S. Seehraen
dc.contributor.authorMouli Roy Chowdhuryen
dc.contributor.authorSingh, H.en
dc.contributor.authorSayandeep Ghoshen
dc.contributor.authorJena, S. K.en
dc.contributor.authorPramanik, P.en
dc.contributor.authorSarkar, T.en
dc.contributor.authorRawat, Rajdeep Singhen
dc.contributor.authorRohit Medwalen
dc.contributor.authorWeise, Brunoen
dc.identifier.citationSubhash Thota, Mohindar S. Seehra, Mouli Roy Chowdhury, Singh, H., Sayandeep Ghosh, Jena, S. K., Pramanik, P., Sarkar, T., Rawat, R. S., Rohit Medwal. & Weise, B. (2022). Unraveling the nature of ferrimagnetism and associated exchange interactions in distorted honeycomb Ni4Nb2O9. Physical Review B, 106(13), Article 134418.
dc.identifier.issn1098-0121 (print)-
dc.identifier.issn1550-235X (online)-
dc.description.abstractFerrimagnetism in orthorhombic Ni<sub>4</sub>, Nb<sub>2</sub> O<sub>g</sub> below its Néel temperature. <i>TFN</i> ~ 76 K is reported to result from two inequivalent Ni<sup>2+</sup> ions having different magnetic moments. However, a clear understanding of the temperature variation of its magnetization [M(T)] for T > <i>TFN</i> and T < <i>TFN</i> in terms of a single set of exchange parameters is still lacking. In this work, experimental results obtained from a detailed analysis of the temperature and magnetic field dependence of magnetization [M(T, H)], ac-magnetic susceptibility [x<sub>ac</sub>,(f, 7, H)], and heat-capacity [C<sub>p</sub> (T, H)] measurements are combined with theoretical analysis to provide new insights into the nature of ferrimagnetism in Ni<sub>4</sub>, Nb<sub>2</sub> O<sub>g</sub>. X-ray diffraction/Rietveld analysis of the prepared sample yielded the structural parameters of the orthorhombic crystal in agreement with previous studies, whereas x-ray photoelectron spectroscopy confirmed the Ni<sup>2+</sup> and Nb<sup>5+</sup> electronic states in Ni<sub>4</sub>, Nb<sub>2</sub> O<sub>g</sub>. Analysis of x<sub>ac</sub>(T) shows the paramagnetic-to-ferrimagnetic transition occurs at 76.5 K <i>TFN</i>, which increases with applied field H as <i>TFN</i> ∝ H<sup>0.35</sup> due to the coupling of the ferromagnetic component with H. For T > <i>TFN</i>, the Xdc versus T' data are fitted to the Néel's expression for ferrimagnets, yielding the g-factors for the two Ni<sup>2+</sup> ions as ga = 2.47 and gp = 2.10. Also, the antiferromagnetic molecular field constants between the A and B sublattices were evaluated as N<sub>AA</sub>, = 26.31, N<sub>BB</sub> = 8.59. and N<sub>AB</sub> = 43.06, which, in turn, yield the antiferromagnetic exchange parameters: J<sub>AA</sub>/kp = 4.27 K, J<sub>BB</sub>/kp = 1.40 K, and J<sub>AB</sub>/k<sub>B</sub> = 6.98 K. For T < <i>TFN</i>, the M versus T data clearly show the magnetic compensation point at T<sub>com</sub> ~ 33 K. The mathematical model presented here using the magnitudes of N<sub>AA</sub>, N<sub>BB</sub> and N<sub>AB</sub> Correctly predicts the position of Toy as well the temperature variation of M both above and below T<sub>COM</sub>. The data of Cp(T) versus T shows a A-type anomaly across Try. After subtracting the lattice contribution, the Cp(T) data are fitted to Cp = A(T — T<sub>N</sub>)(-∝) yielding the critical exponent ∝ = 0.14(0.12) for <i>TFN</i> (T > <i>TFN</i>), which is a characteristic of second-order phase transition. Magnetic entropy changes determined from the M-H isotherms shows that the applied field H enhances the magnetic ordering for T > <i>TFN</i> and T < T<sub>com</sub>. but for T<sub>com</sub> < T <i>TFN</i>, the spin disorder increases with the increase in H. The temperature variation of the measured coercivity Hc(T) and remanence Mpr(T) from 1.9 K to <i>TFN</i> initially show a decreasing trend. becoming zero atT<sub>COM</sub>, then followed by an increase and eventually becoming zero again at <i>TFN</i>.-
dc.relation.ispartofPhysical Review Ben
dc.titleUnraveling the nature of ferrimagnetism and associated exchange interactions in distorted honeycomb Ni4Nb2O9en
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