Quantum Critical Behaviour in Spin and Charge Ordered Systems

SrTiO 3的量子特性，例如其初始铁电性和在最低温度下保持顺电性的趋势，已经吸引了凝聚态物理学家几十年。然而，在这些低温下，SrTiO 3和类似材料在它们的相图中接近于向位移铁电相的转变。这样的材料提供了很好的机会，通过改变外部参数来研究将材料从这种零温度量子临界转变中调谐出来的效果。流体静压的应用调谐SrTiO 3远离量子波动占主导地位的区域，并通过精确的介电测量，允许绘制相图的大区域，并观察可能出现的相位。以这种方式进行的测量也显示了量子临界性和新的可能相边界演化的证据。所使用的技术还应允许研究具有两个或多个耦合序参数的系统中的复杂行为，例如多铁性EuTiO 3。

Quantum properties of SrTiO3, such as its Incipient ferroelectricity and tendency to remain paraelectric down to the lowest temperatures have fascinated condensed matter physicists for several decades. At these low temperatures however SrTiO3 and similar materials lie close to a transition to a displacive ferroelectric phase in their phase diagrams. Such materials offer good opportunities for studying the effects of tuning the material away from this zero-temperature, quantum critical transition by the varying of an external parameter. The application of hydrostatic pressure tunes SrTiO3 away from the region in which quantum fluctuations dominate and, through precise dielectric measurement, allows for a large region of the phase diagram to be mapped and for the observation of possible emergent phases. Measurements taken in this manner have also shown evidence for Quantum Criticality and evolution of a new possible phase boundary. The techniques used should also allow study of complex behaviour in systems with two or more coupled order parameters, such as the multiferroic EuTiO3.