Theoretical description of the colossal entropic magnetocaloric effect: Application to MnAs

Ranke, P.J. von; Gama, S.; Coelho, Leandro dos Santos; Campos, André Gambier; Carvalho, A. Magnus G.; Gandra, F. C. G.; Oliveira, N.A. de

doi:10.1103/physrevb.73.014415

Cited by 67 publications

(43 citation statements)

References 25 publications

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“…Concerning the MnAs compound, recently, some Brazilian groups published a series of papers presenting the colossal magnetic entropy change of this material. [17][18][19][20] At ambient pressure this material has 40 J / kg K at 318 K at 5 T, increasing up to 267 J / kg K at 280 K at 5 T at 2.2 kbar. 19 Small iron substitution on the Mn site, i.e., Mn 1−x Fe x As, induced a chemical pressure and therefore 320 J / kg K was obtained at 310 K, 5 T and ambient external pressure.…”

Section: Introductionmentioning

confidence: 97%

Influence of the strong magnetocrystalline anisotropy on the magnetocaloric properties of MnP single crystal

et al. 2008

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Manganese monophosphate MnP single crystal deserves attention due to its rich magnetic phase diagram, which is quite different depending on the direction of the applied magnetic field. Generally speaking, it has a Curie temperature around 291 K and several other magnetic arrangements at low temperatures ͑cone-, screw-, fan-, and ferromagnetic-type structures͒. This richness is due to the strong magnetocrystalline anisotropy. In this sense, the present paper makes a thorough description of the influence of this anisotropy on the magnetocaloric properties of this material. From a fundamental view we could point out, among those several magnetic arrangements, the most stable one. On the other hand, from an applied view, we could show that the magnetic entropy change around room temperature ranges from −4.7 to − 3.2 J / kg K, when the magnetic field ͑5 T͒ is applied along the easy and hard magnetization directions, respectively. In addition, we have shown that it is also possible to take advantage of the magnetic anisotropy for magnetocaloric applications, i.e., we have found a quite flat magnetic entropy change ͑with a huge relative cooling power͒, at a fixed value of magnetic field, only rotating the crystal by 90°.

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Section: Introductionmentioning

confidence: 97%

Influence of the strong magnetocrystalline anisotropy on the magnetocaloric properties of MnP single crystal

et al. 2008

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“…(5) may also be underestimated. It is also interesting to apply here the theoretical model used recently to explain the colossal magnetocaloric effect (CMCE) in MnAs [25] and compounds of the series Mn 1−x Fe x As [2]. This model considers the Gibbs free energy in stable equilibrium.…”

Section: Resultsmentioning

confidence: 98%

The isothermal variation of the entropy (ΔST) may be miscalculated from magnetization isotherms in some cases: MnAs and Gd5Ge2Si2 compounds as examples

Carvalho

Coelho

Ranke

et al. 2011

Journal of Alloys and Compounds

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“…1 After tuning the magnetic ordering temperature and varying the magnitude of the magnetic field, the application of hydrostatic pressure has been extraordinarily successful in the improvement of the magnetocaloric properties of several materials by increasing the magnitude and/or tuning the MCE to the desired temperature range. Some examples are R 5 ͑Si x Ge 1−x ͒ 4 ͑R = rare earth͒, [2][3][4] MnAs, 5,6 La͑Fe x Si 1−x ͒ 13 , 7 La x Sr 1−x MnO 3 , 8,9 and RMn 2 Ge 2 . 10 However, the physical origin of the pressure effects on the MCE is not always well understood.…”

Section: Introductionmentioning

confidence: 99%

Magnetocaloric effect ofEr5Si4under hydrostatic pressure

et al. 2009

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The magnetocaloric effect ͑MCE͒ of the compound Er 5 Si 4 has been investigated as a function of the applied magnetic field ͑up to 50 kOe͒ and the hydrostatic pressure ͑from ambient pressure up to 9 kbar͒. At constant magnetic field change, increasing the pressure up to 1.4 kbar induces a global rise of the magnetic entropy change, ͉⌬S mag ͉, with the peak at T C Х 30 K growing from 14.9 to 20.1 J / kg K. Between 1.4 and 9 kbar, the size and shape of the ͉⌬S mag ͉ vs T curve remain nearly constant but the peak moves to higher temperatures and stabilizes above 3.5 kbar at T ϳ 36 K. Contrary to many other R 5 ͑Si x Ge 1−x ͒ 4 compounds, the magnetocaloric effect in Er 5 Si 4 does not originate from the simultaneous field-induced magnetic and structural transformations since previous studies of the compound have demonstrated that moderate steady magnetic fields are not strong enough to induce the M → O͑I͒ transformation at the atmospheric pressure. However, the pressure dependence of the MCE is associated with pressure-induced M → O͑I͒ structural transformation that takes place in Er 5 Si 4 . The increase in the magnetic entropy change occurs because of a modification of the magnetic coupling derived from the differences in the interlayer bonding in the M and O͑I͒ states. This gives rise to an enhancement of the ferromagnetic interactions in the O͑I͒ phase with respect to the ambient pressure M state, resulting in a stronger saturation magnetization and a higher Curie temperature, i.e., T C M = 30 K and T C O͑I͒ =36 K.

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Theoretical description of the colossal entropic magnetocaloric effect: Application to MnAs

Cited by 67 publications

References 25 publications

Influence of the strong magnetocrystalline anisotropy on the magnetocaloric properties of MnP single crystal

Influence of the strong magnetocrystalline anisotropy on the magnetocaloric properties of MnP single crystal

The isothermal variation of the entropy (ΔST) may be miscalculated from magnetization isotherms in some cases: MnAs and Gd5Ge2Si2 compounds as examples

Magnetocaloric effect ofEr5Si4under hydrostatic pressure

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