Magnetocaloric effect and magnetic cooling near a field-induced quantum-critical point
Magnetocaloric effect and magnetic cooling near a field-induced quantum-critical point
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DOI：
10.1073/pnas.1017047108
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发表时间：
2011-04-26
影响因子：
11.1
通讯作者：
Lang, Michael
中科院分区：
文献类型：
--
作者：
Wolf, Bernd;Tsui, Yeekin;Lang, Michael
量子临界点 (QCP) 的存在可以显着影响材料在有限温度 T 下的热力学性质。这反映在，例如。例如，在 QCP 附近的熵景观 S(T,r) 中，对于改变诸如压力或磁场 B 之类的调谐参数 r 会产生特别强烈的变化。在这里，我们报告了通过磁热效应 (MCE)、(偏导数 T/偏导数 B)(S) 的绝对测量来确定 B 诱导 QCP 附近偏导数 S/偏导数 B 的临界增强，并证明 QCP 周围熵的积累可用于高效低温磁冷却。我们的原理证明基于 MCE 的测量和理论计算以及含 Cu2+ 配位聚合物的冷却性能，这是自旋 1/2 反铁磁海森堡链（最简单的量子临界系统之一）的很好实现。
The presence of a quantum-critical point (QCP) can significantly affect the thermodynamic properties of a material at finite temperatures T. This is reflected, e. g., in the entropy landscape S(T,r) in the vicinity of a QCP, yielding particularly strong variations for varying the tuning parameter r such as pressure or magnetic field B. Here we report on the determination of the critical enhancement of partial derivative S/partial derivative B near a B-induced QCP via absolute measurements of the magnetocaloric effect (MCE), (partial derivative T/partial derivative B)(S) and demonstrate that the accumulation of entropy around the QCP can be used for efficient low-temperature magnetic cooling. Our proof of principle is based on measurements and theoretical calculations of the MCE and the cooling performance for a Cu2+-containing coordination polymer, which is a very good realization of a spin-1/2 antiferromagnetic Heisenberg chain-one of the simplest quantum-critical systems.