Weak Singularities of the Isothermal Entropy Change as the Smoking Gun Evidence of Phase Transitions of Mixed-Spin Ising Model on a Decorated Square Lattice in Transverse Field

The magnetocaloric response of the mixed spin-1/2 and spin-<i>S</i> (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>S</mi><mo>></mo><mn>1</mn><mo&...

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Autores principales:	Jozef Strečka, Katarína Karl’ová
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	Ising model transverse field exact results magnetocaloric effect weak singularity Science Q Astrophysics QB460-466 Physics QC1-999
Acceso en línea:	https://doaj.org/article/8e812e3becb9486a9f17b3496c7906df
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spelling	oai:doaj.org-article:8e812e3becb9486a9f17b3496c7906df2021-11-25T17:30:40ZWeak Singularities of the Isothermal Entropy Change as the Smoking Gun Evidence of Phase Transitions of Mixed-Spin Ising Model on a Decorated Square Lattice in Transverse Field10.3390/e231115331099-4300https://doaj.org/article/8e812e3becb9486a9f17b3496c7906df2021-11-01T00:00:00Zhttps://www.mdpi.com/1099-4300/23/11/1533https://doaj.org/toc/1099-4300The magnetocaloric response of the mixed spin-1/2 and spin-<i>S</i> (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>S</mi><mo>></mo><mn>1</mn><mo>/</mo><mn>2</mn></mrow></semantics></math></inline-formula>) Ising model on a decorated square lattice is thoroughly examined in presence of the transverse magnetic field within the generalized decoration-iteration transformation, which provides an exact mapping relation with an effective spin-1/2 Ising model on a square lattice in a zero magnetic field. Temperature dependencies of the entropy and isothermal entropy change exhibit an outstanding singular behavior in a close neighborhood of temperature-driven continuous phase transitions, which can be additionally tuned by the applied transverse magnetic field. While temperature variations of the entropy display in proximity of the critical temperature <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>T</mi><mi>c</mi></msub></semantics></math></inline-formula> a striking energy-type singularity <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mrow><mo>(</mo><mi>T</mi><mo>−</mo><msub><mi>T</mi><mi>c</mi></msub><mo>)</mo></mrow><mo form="prefix">log</mo><mrow><mo>\|</mo><mi>T</mi><mo>−</mo><msub><mi>T</mi><mi>c</mi></msub><mo>\|</mo></mrow></mrow></semantics></math></inline-formula>, two analogous weak singularities can be encountered in the temperature dependence of the isothermal entropy change. The basic magnetocaloric measurement of the isothermal entropy change may accordingly afford the smoking gun evidence of continuous phase transitions. It is shown that the investigated model predominantly displays the conventional magnetocaloric effect with exception of a small range of moderate temperatures, which contrarily promotes the inverse magnetocaloric effect. It turns out that the temperature range inherent to the inverse magnetocaloric effect is gradually suppressed upon increasing of the spin magnitude <i>S</i>.Jozef StrečkaKatarína Karl’ováMDPI AGarticleIsing modeltransverse fieldexact resultsmagnetocaloric effectweak singularityScienceQAstrophysicsQB460-466PhysicsQC1-999ENEntropy, Vol 23, Iss 1533, p 1533 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Ising model transverse field exact results magnetocaloric effect weak singularity Science Q Astrophysics QB460-466 Physics QC1-999
spellingShingle	Ising model transverse field exact results magnetocaloric effect weak singularity Science Q Astrophysics QB460-466 Physics QC1-999 Jozef Strečka Katarína Karl’ová Weak Singularities of the Isothermal Entropy Change as the Smoking Gun Evidence of Phase Transitions of Mixed-Spin Ising Model on a Decorated Square Lattice in Transverse Field
description	The magnetocaloric response of the mixed spin-1/2 and spin-<i>S</i> (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>S</mi><mo>></mo><mn>1</mn><mo>/</mo><mn>2</mn></mrow></semantics></math></inline-formula>) Ising model on a decorated square lattice is thoroughly examined in presence of the transverse magnetic field within the generalized decoration-iteration transformation, which provides an exact mapping relation with an effective spin-1/2 Ising model on a square lattice in a zero magnetic field. Temperature dependencies of the entropy and isothermal entropy change exhibit an outstanding singular behavior in a close neighborhood of temperature-driven continuous phase transitions, which can be additionally tuned by the applied transverse magnetic field. While temperature variations of the entropy display in proximity of the critical temperature <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>T</mi><mi>c</mi></msub></semantics></math></inline-formula> a striking energy-type singularity <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mrow><mo>(</mo><mi>T</mi><mo>−</mo><msub><mi>T</mi><mi>c</mi></msub><mo>)</mo></mrow><mo form="prefix">log</mo><mrow><mo>\|</mo><mi>T</mi><mo>−</mo><msub><mi>T</mi><mi>c</mi></msub><mo>\|</mo></mrow></mrow></semantics></math></inline-formula>, two analogous weak singularities can be encountered in the temperature dependence of the isothermal entropy change. The basic magnetocaloric measurement of the isothermal entropy change may accordingly afford the smoking gun evidence of continuous phase transitions. It is shown that the investigated model predominantly displays the conventional magnetocaloric effect with exception of a small range of moderate temperatures, which contrarily promotes the inverse magnetocaloric effect. It turns out that the temperature range inherent to the inverse magnetocaloric effect is gradually suppressed upon increasing of the spin magnitude <i>S</i>.
format	article
author	Jozef Strečka Katarína Karl’ová
author_facet	Jozef Strečka Katarína Karl’ová
author_sort	Jozef Strečka
title	Weak Singularities of the Isothermal Entropy Change as the Smoking Gun Evidence of Phase Transitions of Mixed-Spin Ising Model on a Decorated Square Lattice in Transverse Field
title_short	Weak Singularities of the Isothermal Entropy Change as the Smoking Gun Evidence of Phase Transitions of Mixed-Spin Ising Model on a Decorated Square Lattice in Transverse Field
title_full	Weak Singularities of the Isothermal Entropy Change as the Smoking Gun Evidence of Phase Transitions of Mixed-Spin Ising Model on a Decorated Square Lattice in Transverse Field
title_fullStr	Weak Singularities of the Isothermal Entropy Change as the Smoking Gun Evidence of Phase Transitions of Mixed-Spin Ising Model on a Decorated Square Lattice in Transverse Field
title_full_unstemmed	Weak Singularities of the Isothermal Entropy Change as the Smoking Gun Evidence of Phase Transitions of Mixed-Spin Ising Model on a Decorated Square Lattice in Transverse Field
title_sort	weak singularities of the isothermal entropy change as the smoking gun evidence of phase transitions of mixed-spin ising model on a decorated square lattice in transverse field
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/8e812e3becb9486a9f17b3496c7906df
work_keys_str_mv	AT jozefstrecka weaksingularitiesoftheisothermalentropychangeasthesmokinggunevidenceofphasetransitionsofmixedspinisingmodelonadecoratedsquarelatticeintransversefield AT katarinakarlova weaksingularitiesoftheisothermalentropychangeasthesmokinggunevidenceofphasetransitionsofmixedspinisingmodelonadecoratedsquarelatticeintransversefield
_version_	1718412297385279488

Weak Singularities of the Isothermal Entropy Change as the Smoking Gun Evidence of Phase Transitions of Mixed-Spin Ising Model on a Decorated Square Lattice in Transverse Field

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