Entropy Landscape of Phase Formation Associated with Quantum Criticality in Sr 3 Ru 2 O 7

Abstract

Mapping Out an Entropic Landscape Quantum critical points are continuous phase transitions occurring near absolute zero displaying interesting properties that may have valuable applications. Experimental thermodynamic information on quantum critical systems is sparse, partly because the better known systems are tuned using hydrostatic pressure, and thermodynamic measurements are difficult to perform under such conditions. Rost et al. (p. 1360 , published online 6 August 2009; see the Perspective by Fisk ) built and calibrated bespoke apparatus for a thermodynamic study of strontium ruthenate using a magnetic field as the tuning parameter. The specific heat and magnetocaloric measuremements were combined to map an “entropy landscape” of the quantum criticality and phase formation. This technique should offer a way to probe other materials to reveal unusual properties, such as novel metallic states and superconductivity.