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arXiv 0903.1445cond-mat.str-elcond-mat.stat-mech
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铁电体中的量子临界性

Quantum criticality in ferroelectrics

S. E. Rowley, L. J. Spalek, R. P. Smith, M. P. M. Dean, G. G. Lonzarich, J. F. Scott, S. S. Saxena

摘要:

材料调谐到零温相变附近时,常常会出现新的量子现象。许多研究这些新效应的努力,就像传统的金属费米液体理论的崩溃一样,都集中在窄带电子系统中。铁电晶体提供了一种完全不同类型的量子临界性,这种临界性纯粹来自晶格。在许多情况下,铁电相可以使用流体静压或化学或同位素替代来调谐到绝对零度。在接近这种零温度的相变时,由于电极化的量子涨落,介电常数和其他物理量会变成完全非常规的形式。最简单的铁电体可以形成固态量子临界的教科书范例,因为避免了金属中由于费米表面上的高密度无隙激发而发现的困难。我们提出了低温高精度的数据证明这些影响在纯单晶的SrTiO 3和KTaO 3。我们概述了用于描述接近量子临界的铁电体物理的模型,并强调了在低温下在宽温度范围内测量的介电常数的预期1/T2依赖性。在附近的量子临界点,我们报告出现了一个小的频率无关的峰的介电常数在约2K的SrTiO 3和3 K的KTaO 3认为产生耦合到声学声子。展望未来,我们认为,在铁电材料支持移动载流子,量子顺电波动可能介导新的有效的电子-电子相互作用,从而产生一些可能的状态,如超导。

英文摘要:

Materials tuned to the neighbourhood of a zero temperature phase transition often show the emergence of novel quantum phenomena. Much of the effort to study these new effects, like the breakdown of the conventional Fermi-liquid theory of metals has been focused in narrow band electronic systems. Ferroelectric crystals provide a very different type of quantum criticality that arises purely from the crystalline lattice. In many cases the ferroelectric phase can be tuned to absolute zero using hydrostatic pressure or chemical or isotopic substitution. Close to such a zero temperature phase transition, the dielectric constant and other quantities change into radically unconventional forms due to the quantum fluctuations of the electrical polarization. The simplest ferroelectrics may form a text-book paradigm of quantum criticality in the solid-state as the difficulties found in metals due to a high density of gapless excitations on the Fermi surface are avoided. We present low temperature high precision data demonstrating these effects in pure single crystals of SrTiO3 and KTaO3. We outline a model for describing the physics of ferroelectrics close to quantum criticality and highlight the expected 1/T2 dependence of the dielectric constant measured over a wide temperature range at low temperatures. In the neighbourhood of the quantum critical point we report the emergence of a small frequency independent peak in the dielectric constant at approximately 2K in SrTiO3 and 3K in KTaO3 believed to arise from coupling to acoustic phonons. Looking ahead, we suggest that in ferroelectric materials supporting mobile charge carriers, quantum paraelectric fluctuations may mediate new effective electron-electron interactions giving rise to a number of possible states such as superconductivity.

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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