Abstract

We study the mixed spin-1 and spin-3/2 Blume-Capel model under crystal field in the tridimensional semi-infinite case. This has been done by using the real-space renormalization group approximation and specifically the Migdal-Kadanoff technique. As a function of the ratio R of bulk and surface interactions and the ratios R1 and R2 of bulk and surface crystals fields on the spin-1 and spin-3/2 respectively, we have determined various types of phase diagrams. Besides second- order transition lines, first-order phase transition lines terminating at tricritical points are obtained. We found that there existed nine main types of phase diagram showing a variety of phase transitions associated with the surface, including ordinary, extraordinary, surface and special phase transitions.

Highlights

  • The problems of surface magnetism have been investigated for many years

  • The system of mixed spins S = 1/2 and S = 1 has been one of the simplest to be studied early and largely, namely by the techniques of renormalization group [32] [33], the Bethe-Peierls approximation [34], the effective field theory [35] [36], the MonteCarlo simulation [37] [38] and the finite cluster approximation [39]. This attention has been expanded on systems of mixed spins higher than 1/2, like the case S = 1 and S = 3/2, which has been studied by several methods, as the mean field approximation (MF) [40], the Bethe lattice recursion relations [41] [42], the effective field theory [43] [44], the Monte-Carlo simulation [45], the Green’s function [46], the recursion relations on Cayley tree [47] and the real space renormalization group theory [48]. Our aim in this present paper is to determine the various types of phase diagram in the semi-infinite system of mixed spins S = 1 and S = 3/2 on the Blume-Capel model [28] [29], which we study by using a renormalization group (RG) method, namely the Migdal-Kadanoff one [49] [50], combining the decimation as well as the bond shifting

  • We have studied the pure Blume-Capel model in the semi-infinite case

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Summary

Introduction

The problems of surface magnetism have been investigated for many years. Among them the effects of surface on phase transitions in semi-infinite systems have received increasing interest. This attention has been expanded on systems of mixed spins higher than 1/2, like the case S = 1 and S = 3/2, which has been studied by several methods, as the mean field approximation (MF) [40], the Bethe lattice recursion relations [41] [42], the effective field theory [43] [44], the Monte-Carlo simulation [45], the Green’s function [46], the recursion relations on Cayley tree [47] and the real space renormalization group theory [48] Our aim in this present paper is to determine the various types of phase diagram in the semi-infinite system of mixed spins S = 1 and S = 3/2 on the Blume-Capel model [28] [29], which we study by using a renormalization group (RG) method, namely the Migdal-Kadanoff one [49] [50], combining the decimation as well as the bond shifting.

Infinite Blume-Capel Model
Semi-Infinite Blume-Capel Model
Results and Discussions
Conclusions
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