Jahn-Teller assisted polaron hopping and associated dielectric response of PrFe0.5Mn0.5O2.95

Abstract

The canted G-type antiferromagnet PrFe0.5Mn0.5O2.95 shows an enhanced Jahn-Teller (JT) distortion below 150 K (T*). The resistivity of the grains can be described by variable range hopping between the localized states, and there is a dominant grain boundary contribution to dc resistivity, below T*. Above T*, the total dc resistivity follows small polaron hopping (SPH) conduction. A giant dielectric response is observed, and it can be ascribed to Maxwell-Wagner polarization and SPH mechanism. Despite the low concentration of JT active Mn3+ ions, our result indicates an important role of JT effect on physical properties of PrFe0.5Mn0.5O2.95.

Magnetocaloric effect and spin-phonon correlations in RFe0.5Cr0.5O3 (R = Er and Yb) compounds

“…The obtained values of E a for ErFCO and YbFCO are 0.41±0.04 eV and 0.14±0.004 eV respectively. These values are comparable with the values reported in other oxides, where the relaxation mechanism is attributed to charge carrier hopping between transition metal ions [31,32]. In the present scenario, dielectric relaxation can arise from two independent mechanisms: i) Hopping of charge carriers between Cr 3+ and Fe 3+ in the presence of electric field, which give rise to Debye type of relaxation; ii) Accumulation of charge carriers between regions in the sample i.e.…”

Effect of doping of Co, Ni and Ga on magnetic and dielectric properties of layered perovskite multiferroic YBaCuFeO5

“…In our case the best fit is obtained with the Arrhenius law [21] of the form Doped SrTiO 3 (0.74 to 0.86 eV) [22], Bi 4 Ti 3 O 12 (0.87 eV) [23] and Bi 5 TiNbWO 15 (0.76 eV) [24] where the relaxation mechanism is ascribed to the thermal motion of oxygen vacancies. However, the values of E a is comparable to that observed for La 2 CoIrO 6 (0.056 eV) [25], Ca 3 Co 1.4 Rh 0.6 O 6 (0.071 eV) [26], BiMn 2 O 5 (0.065 eV) [27] and PrFe 0.5 Mn 0.5 O 2.9 (0.19 eV) [28] where the relaxation behavior is due to the charge carrier hoping. The values of the activation energy of the studied compounds are comparable to the values observed for the charge carrier hoping.…”

Disordered ferromagnetism in Ho2NiMnO6double perovskite

“…Both the thermally activated relaxation mechanisms are seen to obey Arrhenius law. Since the peaks in δ tan are broad for the low temper ature relaxation (around 225 K), positions of those peaks can be extracted by similar method used by Ganeshraj et al [38]. Peak fitting considering Gaussian peak superimposed on exponentially increasing background has been done in the present case.…”