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arXiv 1012.3328cond-mat.str-el
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磁热效应和场诱导量子临界点附近的磁冷却

Magnetocaloric effect and magnetic cooling near a field-induced quantum-critical point

B. Wolf, Y. Tsui, D. Jaiswal-Nagar, U. Tutsch, A. Honecker, K. Removic-Langer, G. Hofmann, A. Prokofiev, W. Assmus, G. Donath, M. Lang

摘要:

量子临界点(QCP)的存在会显著影响材料在有限温度T下的热力学性质。这反映在,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的调谐参数r,产生特别强的变化。在这里,我们报告的确定的临界增强的$ δS / δB$附近的B-诱导QCP通过绝对测量的磁热效应(MCE),$(δT / δB)_S$,并证明,周围的QCP的熵的积累可用于有效的低温磁冷却。我们的原理证明是基于测量和理论计算的MCE和冷却性能的Cu $^{2+}$ -含有配位聚合物,这是一个非常好的实现自旋1/2反铁磁海森堡链-最简单的量子临界系统之一。

英文摘要:

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 $ δS / δB$ near a B-induced QCP via absolute measurements of the magnetocaloric effect (MCE), $(δT / δB)_S$, 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 Cu$^{2+}$-containing coordination polymer, which is a very good realization of a spin-1/2 antiferromagnetic Heisenberg chain - one of the simplest quantum-critical systems.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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