Enhanced magnetocaloric effect and magnetic phase diagrams of single-crystal<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>GdCrO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>
Yinghao Zhu, Pengfei Zhou, Tao Li, Junchao Xia, Si Wu, Ying Fu, Kaitong Sun, Qian Zhao, Zhen Li, Zikang Tang, Yinguo Xiao, Zhenqiang Chen, Haifeng Li
Abstract
The crystalline structure, magnetism, and magnetocaloric effect of a ${\mathrm{GdCrO}}_{3}$ single crystal grown with the laser-diode-heated floating-zone technique have been studied. The ${\mathrm{GdCrO}}_{3}$ single crystal crystallizes into an orthorhombic structure with the space group $Pmnb$ at room temperature. Upon cooling, under a magnetic field of 0.1 T, it undergoes a magnetic phase transition at ${T}_{\text{N-Cr}}=169.28(2)$ K with ${\mathrm{Cr}}^{3+}$ ions forming a canted antiferromagnetic (AFM) structure, accompanied by weak ferromagnetism. Subsequently, a spin reorientation takes place at ${T}_{\text{SR}}=5.18(2)$ K due to ${\mathrm{Gd}}^{3+}\text{\ensuremath{-}}{\mathrm{Cr}}^{3+}$ magnetic couplings. Finally, the long-range AFM order of ${\mathrm{Gd}}^{3+}$ ions establishes at ${T}_{\text{N-Gd}}=2.10(2)$ K. Taking into account the temperature-(in)dependent components of ${\mathrm{Cr}}^{3+}$ moments, we obtained an ideal model for describing the paramagnetic behavior of ${\mathrm{Gd}}^{3+}$ ions within 30--140 K. We observed a magnetic reversal (positive $\ensuremath{\rightarrow}$ negative $\ensuremath{\rightarrow}$ positive) at 50 Oe with a minimum centering around 162 K. In the studied temperature range of 1.8--300 K, there exists a strong competition between magnetic susceptibilities of ${\mathrm{Gd}}^{3+}$ and ${\mathrm{Cr}}^{3+}$ ions, leading to puzzling magnetic phenomena. We have built the magnetic-field-dependent phase diagrams of ${T}_{\text{N-Gd}}$, ${T}_{\text{SR}}$, and ${T}_{\text{N-Cr}}$, shedding light on the nature of the intriguing magnetism. Moreover, we calculated the magnetic entropy change and obtained a maximum value at 6 K and $\mathrm{\ensuremath{\Delta}}{\ensuremath{\mu}}_{0}H=14$ T, i.e., $\ensuremath{-}\mathrm{\ensuremath{\Delta}}{S}_{\text{M}}\ensuremath{\approx}57.5$ J/kg K. Among all $R{\mathrm{CrO}}_{3}$ ($R=4{f}^{n}$ rare earths, $n=$ 7--14) compounds, the single-crystal ${\mathrm{GdCrO}}_{3}$ compound exhibits the highest magnetic entropy change, as well as an enhanced adiabatic temperature, creating a prominent magnetocaloric effect for potential application in magnetic refrigeration.