Second-order magnetic critical points at finite magnetic fields: Revisiting Arrott plots

Abstract

The so-called Arrott plot, which consists in plotting H/M against M 2 , with H the applied magnetic field and M the magnetization, is used to extract valuable information in second-order magnetic phase transitions. Besides, it is widely accepted that a negative slope in the Arrott plot is indicative of a first-order magnetic transition. This is known as the Banerjee criterion. In consequence, the zero-field transition temperature T * is reported as the characteristic first-order transition temperature. By carefully analyzing the mean-field Landau model used for studying first-order magnetic transitions, we show in this work that T * corresponds in fact to a triple point where three first-order lines meet. More importantly, this analysis reveals the existence of two symmetrical second-order critical points at finite magnetic field (T c ,±H c). We then show that a modified Arrott plot can be used to obtain information about these second-order critical points. To support this idea we analyze experimental data on La 2/3 Ca 1/3 MnO 3 and discuss an estimate for the location of the triple point and the second-order critical points.

Magnetic instability and f – d hybridization in CeFe 2 on substituting Cr, Ag, and Au for Fe

“…7(a)) suggest that the first (PM to FM) transition is of second order, 25 in consistence with the literaure. The change of curvature happens at around 210 K, putting the T C1 value for this pseudobinary at ∼ 210 K. However, the Arrott plots near T C2 have a tendency to have a negative slope beyond 40 K. This clearly indicates that the second (FM to AFM) transition is of first order nature 25 and that the T C2 value for this pseudobinary is ∼ 40 K.…”

Evidence of partial gap opening and Ce-site dilution effects in a heavy fermion compound CeNiGe2

“…Also for first order transition the value of the negative slope should increase with increasing temperature which is in contrast to that observed for Y-0.0 compound where the value of the negative slope decreases. Such opposite behavior has been studied by taking into account the asymmetry of the free energy density with respect to the magnetization and it was observed that a negative slope is possible at second order phase transition with the slope value decreasing with increasing temperature [24]. Also the first order are collected under the field cooled condition in the field range of 0 -1 T by the protocol described in Ref [26].…”

Tuning of structural phase, magnetic spin order and electrical conductivity in mechanical alloyed material of α-Fe2O3 and α-Cr2O3 oxides

“…H/M curves in Fig. 9 (k-o)) is a powerful technique to distinguish first-order phase transition from second order phase transition below Curie point (T C ) of a FM [33][34]. According to Banerjee criterion [34][35], is positive for second-order and negative for first order phase , where a competitive magnetic spin order between the low temperature surface spin order and high temperature CAFM spin order is observed in the temperature range 100 K-150 K. The spin flop field (H sf ), an important parameter for changing magnetic spin order from low magnetic state (AFM) to high magnetic state (CAFM), varied on the variation of both Cr content and measurement temperature of the A10 samples (Fig.…”