Magnetic molecular clusters as promising materials for refrigeration in low-temperature regions

Abstract

A wide class of magnetic molecular materials - molecular clusters with high magnetic moment containing 3d transition metals (such as `Fe8', `Mn12ac', etc) - have been considered from the point of view of their use as refrigerants in low-temperature regions. The consideration was made in the framework of the model based on the Langevin theory of a superparamagnet. The magnetic entropy change caused by a change in an external magnetic field was calculated for various magnetic clusters. The estimations made show that the magnetic molecular clusters could be promising materials for magnetic refrigeration in low-temperature regions (below about 20 K).

Giant magnetocaloric effect in magnetoelectric Eu1-xBaxTiO3

“…liquefaction of hydrogen, infrared bolometer) in the temperature range of 1 -20 K. 7 Superparamagnetic molecular magnetic clusters and gadolinium garnet (Gd 3 Ga 5 O 12 ) are considered as potential magnetic refrigerants in this temperature range. 8 In this work, we report the occurrence of a giant magnetocaloric effect at cryogenic temperatures (T < 30 K) in a novel class of magnetoelectric materials, Eu 1-x Ba x TiO 3, whose end members have distinct ferroic orders. While EuTiO 3 (x = 0) is a paraelectricantiferromagnet, BaTiO 3 (x = 1) is a ferroelectric-nonmagnet.…”

Direct and indirect measurement of the magnetocaloric effect in bulk and nanostructured Ni-Mn-In Heusler alloy

“…20 Nanoscaled magnetic materials are good candidates for magnetic refrigeration due to a presence of a large MCE in the superparamagnetic system and reduced hysteresis losses. 17,[21][22][23][24][25][26][27] Additionally, magnetocaloric nanoparticles have a broader entropy change over a wider temperature span which may results in a higher relative cooling power (RCP) that is defined as RCP = −∆S M (T , H)×δT FWHM , where ∆S M is the refrigerant's magnetic entropy change and δT FWHM is the full-width-at-halfmaximum of the peak of magnetic entropy. 28,29 RCP measures how much heat can be transferred between the cold and hot heat exchangers in an ideal refrigeration cycle.…”

Isothermal Entropy Change and Adiabatic Change of Temperature of the Antiferromagnetic Spin-1/2 Ising Octahedron and Dodecahedron

“…An importance of the MCE consists in its potential usage for a magnetic refrigeration through the process of adiabatic demagnetization [1]. The magnetic materials with the large MCE are therefore of technological interest with regard to their cooling capability either at room or low temperatures [2].…”