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

Abstract

Low-temperature phase transitions and the associated quantum critical points are a major field of research, but one in which experimental information about thermodynamics is sparse. Thermodynamic information is vital for the understanding of quantum many-body problems. We show that combining measurements of the magnetocaloric effect and specific heat allows a comprehensive study of the entropy of a system. We present a quantitative measurement of the entropic landscape of Sr3Ru2O7, a quantum critical system in which magnetic field is used as a tuning parameter. This allows us to track the development of the entropy as the quantum critical point is approached and to study the thermodynamic consequences of the formation of a novel electronic liquid crystalline phase in its vicinity.

Signatures of quantum criticality in the thermopower of Ba(Fe1−xCox)2Arsenijević1, Hodovanets2, Gáal3 et al. 2013Phys. Rev. B331320View full textAdd to dashboardCite

“…The link between the increase of S/T and anisotropic spin fluctuations close to QCP is observed in other systems too. The increase of S/T at x c from both the higher and lower Co substitution sides is reminiscent of the behavior observed in Sr 3 Ru 2 O 7 , in which magnetic field was used as a tuning parameter to approach the QCP [22]. Jumps in magnitude observed there in two thermodynamic variables, entropy and specific heat, were ascribed to the formation of a spin nematic phase of electronic fluid with broken rotational symmetry.…”

“…There, the enhanced scattering by critical spin fluctuations (SF) close to the antiferromagnetic (AF) quantum critical point leads to an increase of electronic entropy and, consequently, to increases of thermopower and electronic specific heat (C e ) [21]. The increase of entropy and C e upon entering the nematic phase in the vicinity of the quantum critical phase was shown in the example of Sr 3 Ru 2 O 7 [22]. In this paper, we observe quantum critical behavior by thermopower in the phase diagram of the prototypical Fe-based superconductor Ba(Fe 1−x Co x ) 2 As 2 (BFCA).…”

Quantum oscillations near the metamagnetic transition inSr3Ru2O7

“…In order to search for the oscillations, we profited from bespoke equipment developed in St Andrews for the study of the magnetocaloric effect. 9 In contrast to second harmonic dHvA, the relative signal size will be independent of F in principle, but subject to a damping factor that will grow rapidly with F since more rapid oscillations will be damped more strongly in a measurement system with long intrinsic relaxation times.…”

Quantum phase transitions of a generalized compass chain with staggered Dzyaloshinskii–Moriya interaction

“…For the particle-hole excitation spectrum (23), the free energy of the quantum spin chain at temperature T reads (here and below we use the units with the Boltzmann constant k B ≡ 1), Among many thermodynamic quantities, the entropy S provides fundamental information about the evolution of spectra with increasing the temperature T . The complete entropic landscape was recently quantitatively measured for Sr 3 Ru 2 O 7 under magnetic field in the vicinity of quantum criticality 36 . It can be derived from the free energy F (29) via the following thermodynamic relation, Figure 7 demonstrates the entropy S as a function of the DM field E and the temperature T when the DM interaction is uniform.…”