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arXiv 2007.07763cond-mat.stat-mech
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横晶场中自旋3/2量子铁磁Blume-Capel模型的Phase diagram:平均场近似

Phase diagram for the spin-3/2 quantum ferromagnetic Blume-Capel model in a transverse crystal field: an approximation at the mean-field level

D. C. Carvalho, J. A. Plascak

摘要:

在自由能Bogoliubov不等式的框架下,利用标准平均场近似,研究了横向晶场中自旋$3/2$铁磁Blume-Capel模型的相图.我们画了一个非常丰富的相图,一阶和二阶过渡线;三临界点和四临界点; 2阶临界端点和双临界端点。此外,磁化强度作为温度的函数在很宽的范围内的值的纵向和横向晶体场的行为进行了分析。据我们所知,这种量子自旋模型只采用了有效场论,而有效场论又不能完全解释其相图中的多临界现象,因为该过程不是基于自由能的。因此,我们的研究结果对本模型的相图是新颖的,因为他们没有以前的报道。

英文摘要:

We investigate the phase diagram for the spin-$3/2$ ferromagnetic Blume-Capel model in a transverse crystal field using the standard mean-field approximation within the framework of Bogoliubov inequality for free energy. We draw a very rich phase diagram with first- and second-order transition lines; tricritical and tetracritical points; critical endpoint of order 2 and double critical endpoint. Additionally, the behaviour of magnetisation as a function of temperature over a wide range of values of both longitudinal and transverse crystal fields is also analysed. To the best of our knowledge, this quantum spin model has only been studied employing an effective field theory, which in turn was not able to characterise completely the multicritical phenomena in its phase diagram, because that procedure is not based on free energy. Thus, our findings on the phase diagram for the present model are novel as they have been not previously reported.

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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