Giant multiple caloric effects in charge transition ferrimagnet

Yoshihisa Kosugi,Daisuke Kan,Hidenori Takagi,Masato Goto,Masaichiro Mizumaki,Masahiko Isobe,Zhenhong Tan,Kenji Yoshii,Yuichi Shimakawa,Asaya Fujita

doi:10.1038/s41598-021-91888-8

Abstract

Caloric effects of solids can provide us with innovative refrigeration systems more efficient and environment-friendly than the widely-used conventional vapor-compression cooling systems. Exploring novel caloric materials is challenging but critically important in developing future technologies. Here we discovered that the quadruple perovskite structure ferrimagnet BiCu3Cr4O12 shows large multiple caloric effects at the first-order charge transition occurring around 190 K. Large latent heat and the corresponding isothermal entropy change, 28.2 J K−1 kg−1, can be utilized by applying both magnetic fields (a magnetocaloric effect) and pressure (a barocaloric effect). Adiabatic temperature changes reach 3.9 K for the 50 kOe magnetic field and 4.8 K for the 4.9 kbar pressure, and thus highly efficient thermal controls are achieved in multiple ways.

Highlights

Caloric effects of solids can provide us with innovative refrigeration systems more efficient and environment-friendly than the widely-used conventional vapor-compression cooling systems
As shown in the result of differential scanning calorimetry (DSC) measurement (Fig. 1b), the observed heat flow shows thermal hysteresis of 4 K between the cooling and heating process, and the latent heat estimated from the data on cooling is 5.23 kJ kg−1 (Table S2)
We presented the experimental results of Magnetocaloric effects (MCEs) and barocaloric effect (BCE) separately, we believe that the observed large entropy changes can be utilized by applying both magnetic fields and pressure simultaneously and the compound is multicaloric, because the charge, the spins, and the lattice are strongly coupled in the present B iCu3Cr4O12

Summary

Introduction

Caloric effects of solids can provide us with innovative refrigeration systems more efficient and environment-friendly than the widely-used conventional vapor-compression cooling systems. Large latent heat and the corresponding isothermal entropy change, 28.2 J K −1 k g−1, can be utilized by applying both magnetic fields (a magnetocaloric effect) and pressure (a barocaloric effect). Adiabatic temperature changes reach 3.9 K for the 50 kOe magnetic field and 4.8 K for the 4.9 kbar pressure, and highly efficient thermal controls are achieved in multiple ways. In this paper we report that the A-site ordered quadruple perovskite structure ferrimagnetic oxide BiCu3Cr4O12 shows giant multiple caloric effects; that is, it shows both magnetocaloric and barocaloric effects and they are large. The compound exhibits large latent heat by the first-order charge transition at 190 K, and the corresponding giant entropy change can be utilized through the magnetocaloric and barocaloric effects respectively by applying magnetic fields and pressure. Electronic instability of a mixed-valence state of the constituent transition-metal cation and strong correlation in charge–spin–lattice degrees of freedom in B iCu3Cr4O12 are crucial for giving rise to the observed multiple caloric effects

Methods

Results

Conclusion