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arXiv cond-mat/0209010cond-mat.soft
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表面耦合对润湿和分层转变的影响

Surface coupling effect on wetting and layering transitions

L. Bahmad, A. Benyoussef, H. Ez-Zahraouy

摘要:

利用平均场理论研究了自旋为1/2的伊辛膜的分层转变温度$T_L$随厚度$N$的变化关系中表面耦合$J_s$的影响。据发现,对于大于临界值($J_{sc}=1.30$)的$J_s$,分层转变温度降低时,膜厚度$N$增加的表面磁场$H_s$的任何值。而对于$J_s < J_{sc}$,作为$N$的函数的分层转变温度$T_L$的行为强烈地依赖于$H_s$的值。实际上,我们发现存在三种不同的$T_L$行为,作为膜厚度$N$的函数,由两个临界表面磁场$H_{sc1}$和$H_{sc2}$分开,即:$(i)$对于$H_s < H_{sc1}$,$T_L$随$N$增加; $(ii)$对于$H_{sc1} < H_s < H_{sc2}$,$T_L$随$N$的小值增加,随$N$的大值减少;(iii)而对于$H_s > H_{sc2}$,$T_L$随着膜厚度的增加而减小。此外,取决于$J_s$的值,润湿温度$T_w (T_w=T_L$(当给定材料为$N \to \infty$时)可以大于或小于相同材料的厚度为$N$的膜的分层转变温度。

英文摘要:

The effect of the surface coupling $J_s$ on the dependency of the layering transition temperature $T_L$ as a function of the thickness $N$, of a spin-1/2 Ising film, is studied using the mean field theory. It is found that for $J_s$ greater than a critical value ($J_{sc}=1.30$), the layering transition temperature decreases when the film thickness $N$ increases for any values of the surface magnetic field $H_s$. While, for $J_s < J_{sc}$, the behaviour of the layering transition temperature $T_L$, as a function of $N$, depends strongly on the values of $H_s$. Indeed, we show the existence of three distinct behaviours of $T_L$, as a function of the film thickness $N$, separated by two critical surface magnetic fields $H_{sc1}$ and $H_{sc2}$, namely: $(i)$ for $H_s < H_{sc1}$, $T_L$ increases with $N$; $(ii)$ for $H_{sc1} < H_s < H_{sc2}$, $T_L$ increases for small values of $N$, and decreases for large value ones; (iii) while for $H_s > H_{sc2}$, $T_L$ decreases with increasing the film thickness. Furthermore, depending on the values of $J_s$, the wetting temperature $T_w (T_w=T_L$ when $N \to \infty$ for a given material), can be greater or smaller than the layering transition temperature of a film of thickness $N$ of the same material.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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