Critical Behavior Near the Paramagnetic to Ferromagnetic Phase Transition Temperature in Sr1.5Nd0.5MnO4 Compound

Abstract

The magnetic properties and the critical behavior in Sr 1.5 Nd 0.5 MnO 4 have been investigated by magnetization measurements. The magnetic data indicate that the compound exhibits a second-order phase transition. The estimated critical exponents derived from the magnetic data using various techniques such as modified Arrott plot, Kouvel-Fisher method, and critical magnetization isotherms M (T C , H ). The critical exponent values for this compound was found to match well with those predicted for the mean-field model (δ = 2.212 ± 0.124, γ = 0.975 ± 0.018, and β = 0.502 ± 0.012) at T C = 228.59 ± 0.17. The critical exponent γ is slightly inferior than predicted from the mean-field model. Such a difference may be due, within the context of the quenched disorder and essentially the presence of the Griffiths phase. The temperature variation in the effective exponent (γ eff ) is similar to those for disordered ferromagnets.

Tricritical point from high-field magnetoelastic and metamagnetic effects in UN

“…At T = 48 K by using the Widom scaling relation, δ = 1 +  γ / β , and by taking the mean field value of γ  = 1 we have estimated β  = 0.48 38, 39 . This value of β is close to the mean field result β  = 0.5 37 . Figure 5(b) shows the plot of | ε 100 || t | − β as a function of μ 0 H | t | −( β + γ) , where t  = ( T  −  T N ) is the reduced temperature 37 and by taking γ  = 1 and β  = 0.5.…”

“…This value of β is close to the mean field result β  = 0.5 37 . Figure 5(b) shows the plot of | ε 100 || t | − β as a function of μ 0 H | t | −( β + γ) , where t  = ( T  −  T N ) is the reduced temperature 37 and by taking γ  = 1 and β  = 0.5. As seen from the figure the MS curves below T N and down to 30 K follow the universal scaling law.…”

“…The MS at 48 and 45 K shows a critical power law behaviour ε 100 ∝ H −1/ δ , where δ is a critical exponent 36 . The dotted lines shows the fitting of the data to the power law with the critical exponent δ = 3.1 obtained for 48 K. This δ value is in good agreement with the theoretical value of 3 estimated in the mean field approximation 36 , 37 . With lowering temperature the δ value decreases and at T = 45 K equals to 2.2 (see Fig.…”

Evidence of Ferromagnetic Clusters and Griffiths Singularity in Magnetic Weyl Semimetal Co$ _{3} $Sn$ _{2} $S$ _{2} $

“…It is noticed that the curves exhibit a high field or linear behaviour with a strong downward curvature at very low magnetic fields (insets of figures 7(a) and 7(b)). Similar convex behaviour in M 2 is reported in typical itinerant ferromagnetic materials such as MnSi [23] and transition metal oxide Sr 1.5 Nd 0.5 MnO 4 [72]. According to Banerjee's criterion, the convex downward curvature observed along the two directions resembles a second order phase transition [73].…”

“…Here, p c = (1 + p 2 eff ) − 1 is the magnetic moment, in units of µ B , in the paramagnetic phase and p eff is the effective magnetic moment calculated from Curie-Weiss law. Such itinerant ferromagnetism principally arises from the screening effect of electrons in the band structure due to electron-electron correlations and exchange interactions [72].It is pertinent to note that the factors p c /p s and T C /T 0 are the important parameters for characterising the degree of itinerancy of electrons [78].Now using the linearly fitted slope ζ and intercept values in the Arrott plot of M 2 vs. H/M in figures 7(a) and 7(b), we can estimate the parameters coupling term F 1 and the spontaneous magnetic moment p s , respectively. The derived values of F 1 , p s and p eff for both the directions are listed in the Table III.…”