(Color online) The experimental x ray diffraction pattern of Tb2NiMnO6 along with the results of Rietveld analysis. A minor impurity phase of Tb2O3 was identified and quantified as 4 wt. %. The inset presents a schematic of the crystal structure in monoclinic P21/n space group. The large pink spheres represent Tb the small green ones are oxygen. The network of corner-sharing octahedra is indicated with N/Mn at the center of the octahedra.
(Color online) Main panel: The ZFC and FC magnetization curves of Tb2NiMnO6 at 100 Oe. The magnetic transition is evident at Tc ∼ 111. Insets (a) and (b) show the ZFC and FC curves at 500 and 20 kOe, respectively.
(Color online) Main panel: The specific heat of Tb2NiMnO6 confirming the phase transition of the Ni/Mn lattice at Tc ∼ 111 K. A broad hump-like feature is observed at low temperature, which is related to Schottky effect. The inset represents the fit to the low temperature Cp assuming a polynomial expansion in powers of T.
(Color online) Main panel: The inverse susceptibility 1/χ(T) at different applied fields 20 Oe, 500 Oe, 20 kOe, and 40 kOe. As the applied magnetic field increases, the downward deviation is suppressed. The inset (a) presents the CW analysis of 1/χ(T) at 20 Oe holds only at T Tc . Inset (b) displays log-log plot of the power law analysis of low-field magnetic susceptibility, χ −1(T) ∞ (T − TC R )1−λ . The back solid lines represent the fit to the experimental data following the power law.
(Color online) (a) The magnetization plots at 5, 10, and 50 K. (b) The Arrott plots (M 2 vs H/M) at different temperatures below and above Tc . The straight lines are the linear fits to the high-field region in the plot. No spontaneous magnetization is observed in the temperature range near Tc supporting the Griffiths phase-like characteristics.
(Color online) The FCC and FCW cycles at 20 Oe showing a prominent hysteresis of the first-order type resulting from the ferromagnetic clusters that form below Tc .
(Color online) (a) Observed Raman scattering intensity curves of Tb2NiMnO6 at different temperatures. (b) The intensity at 298 K as a function of Raman shift, displaying peaks at ∼650 cm−1, 510 cm−1, and 490 cm−1 (thick line). The shaded areas represent a curve-fit to the observed spectrum using Lorenzian line shape.
(Color online) (a) The temperature variation of phonon frequencies in Tb2NiMnO6. The solid line is the fit according to the anharmonic phonon-phonon scattering. A vertical black dotted line marks the position of Tc ≅ 111 K. (b) The FWHM for the peak at 645 cm−1 calculated from the experimental Raman intensity as a function of temperature. Note the three different slopes in three different temperature ranges. The red dashed line show typical behavior of FWHM, whereas the solid line represents the anomalous region. The inset displays curves that correspond to peaks at 490 and 509 cm−1; these do not show a slope change.
The structural parameters and selected bond distances and bond angles of Tb2NiMnO6 at room temperature. The atomic positions were Tb 4e(x,y,z), Ni 2c(0.5,0,0.5), Mn 2d(0.5,0,0), and O 4e(x,y,z). TM stands for the transition metal at the B site, Co, or Mn. BVS indicates bond valence sum values.
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